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Aim: This study investigated the effect of neoadjuvant chemotherapy (NAC) on stromal tumor-infiltrating lymphocytes (sTILs) and their treatment response. Materials & methods: 115 patients with pre-NAC core biopsies and post-NAC surgical resection specimens were reviewed. Results: There was no significant change between pre- and post-treatment sTILs. Both pre- and post-NAC sTILs were significantly lower in patients with luminal A subtype. An increase in sTILs was observed in 21 (25.9%) patients after NAC, a decrease in 29 (35.8%) and no change in 31 (38.3%; p = 0.07). Pretreatment sTIL density was independent predictor of pathological complete response in multivariate analyses (odds ratio: 1.025, 95% CI: 1.003-1.047; p = 0.023). Conclusion: High sTIL density in core biopsies was independently related to pathological complete response. In addition, ER appears to be the most crucial factor determining the rate of sTIL. New studies have shown that the tumor microenvironment is critical in tumor behavior. Immune cells surrounding tumor cells are the main components of the tumor microenvironment. Our study aimed to investigate the change in immune cells before and after chemotherapy in breast cancer patients. Our study included 115 patients. All patients underwent chemotherapy before surgery to shrink the tumor. Tru-cut biopsy pieces and the breast tissue obtained after surgery were examined. The presence of estrogen or progesterone receptors on tumor cells decreased the number of immune cells surrounding the tumor cells. The number of immune cells did not decrease after chemotherapy. Another finding was that the greater the number of immune cells around the tumor, the more likely that the tumor would disappear after chemotherapy.

Background Hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) is a chronic Epstein-Barr virus (EBV)-positive lymphoproliferative disease which may either present as an indolent condition or progress to a systemic T-cell lymphoma. Methods All HVLPD diagnosed over a 10-year period were retrieved and clinical data regarding sex, age, oral and systemic manifestations, and clinical follow-up were obtained. Immunohistochemistry was done in order to characterize the lymphoid cells and in situ hybridization was used to demonstrate the presence of EBV. Results Eleven cases were included, with a male predominance and a mean age of 25.1 years. Buccal mucosa and the lips were the most affected oral sites, appearing as painful ulcers. All patients exhibited facial oedema, usually affecting the lips, nose, and periorbital region. The clinical course was gradual but progressive, with four patients having fever and 3 showing lymphadenopathies. All cases showed a moderate to severe lymphocytic infiltrate with angiotropism, angiocentricity and epidermotropism. Two cases affecting the lip skin exhibited a periappendageal lymphocytic infiltrate. Few large pleomorphic cells were found, surrounded by smaller and medium-sized lymphoid cells, as well as reactive plasma cells, macrophages, neutrophils, and eosinophils. All lesions exhibited a cytotoxic T cell (CD8 +) phenotype with a variable proliferative index. All cases were associated with EBV and all patients died due to complications of the disease. Conclusions HVLPD is a rare disease that may show oral involvement with a cytotoxic T-cell phenotype, and is strongly associated with EBV. As shown in this series, HVLPD may show aggressive clinical behaviour.

Carcinoma cuniculatum (CC) is a rare variant of squamous cell carcinoma (SCC) that is characterized by minimal cytologic atypia and a unique deeply infiltrative growth pattern resembling rabbit burrows (cuniculi). With less than 75 cases reported in the head and neck, the clinical and pathologic spectrum of this entity remains poorly understood. A retrospective review of the clinical and pathologic features of archival cases of oral CC was performed. A total of six cases of oral CC were identified. Age ranged from 25-77 years; the male-to-female ratio was 5:1. All patients had a long-standing history of tobacco and betel-quid consumption. The tumors were distributed in the gingivobuccal sulcus (n = 2), the tongue (n = 2), buccal mucosa (n = 1), and the palate (n = 1). Histology in all cases typically revealed a tumor composed of well-differentiated squamous epithelium, devoid of atypia, lining deeply infiltrative, large-sized, branching, keratin-filled cavities, resembling rabbit-burrows. Dense lymphocytic infiltrates and discharging micro-abscesses were regular features. Underlying bone invasion and lymph node metastasis were observed in 1 patient. One patient with a tongue tumor developed locoregional recurrence at 10 months while none developed distant metastasis. Oral CC is a rare and under-recognized variant of SCC with locally aggressive behavior. Lack of familiarity with this variant exacerbated by the absence of cytologic anaplasia makes CC susceptible to multiple negative biopsies and erroneous diagnoses. Awareness of this clinicopathologic entity is essential to allow its accurate diagnosis and optimal management.

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder is a benign lymphoproliferative disorder composed of small-sized to medium-sized pleomorphic cells expressing a follicular helper T-cell phenotype. Jessner lymphocytic infiltrate and tumid lupus are cutaneous conditions characterized by the presence of rich dermal lymphocytic infiltrates with a superficial, deep, perivascular and periadnexal distribution that include copious amounts of dermal mucin deposition. We report 2 cases of primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder presenting with markedly increased dermal mucin, mimicking both Jessner lymphocytic infiltrate and tumid lupus and provide a review of the differential diagnosis and highlight key distinguishing features.

Amiodarone (AMD) is a class III antiarrhythmic drug whose chronic or high dosage administration alters the tests of thyroid function. AMD is also associated with hypothyroidism or thyrotoxicosis. Total thyroidectomy is an efficient treatment of AMD-induced thyrotoxicosis in cases resistant to medical therapy, worsening of cardiac function and/or severe thyrotoxicosis. Although AMD is a widely used drug, its pathological consequences are not well known. We describe the pathological findings in the thyroid gland of a patient who underwent total thyroidectomy due to AMD-induced thyrotoxicosis. The surgical specimen was macroscopically normal, but histologically showed multiple follicles totally or partially invaded by clear vacuolated (foamy) histiocytes, sometimes multinucleated. Loss of thyrocytes, breaks in the follicular basal membrane and stromal fibrosis could also be appreciated but no lymphocytic infiltrates were found. An awareness of these histopathological features is particularly important for surgical pathologists, especially as there are very few published reports describing these alterations.

Cutaneous lupus erythematosus (CLE) is an autoimmune skin disorder that is characterized by an anti-epidermal lymphocytic infiltrate invading the dermo-epidermal junction, causing an interface dermatitis (ID). Pathogenesis of CLE has been linked to activation of innate immunity. NKG2D is an innate immune receptor on NK cells and distinct T-cell populations. The NKG2D ligands MHC class I polypeptide-related sequence A and B (MICA, MICB) have been associated to CLE susceptibility. Our gene microarray analyses of chronic discoid lupus erythematosus (CDLE) skin lesions, separated in epidermal, junctional and dermal skin areas via laser microdissection, revealed a high expression of NKG2D in the lymphocytic infiltrate and led us to further investigate the role of NKG2D in CLE. Pathway analyses showed a strong "interferon (IFN) signature" and vast activation of innate immune response pathways (TLR, RIG-I, cytosolic DNA sensing, JAK/STAT) in CDLE, that expressed the high NKG2D signal. Immunohistochemistry (IHC) confirmed the presence of NKG2D and its ligand MICB in CDLE and subacute cutaneous lupus erythematosus (SCLE) lesions. Finally, HaCaT cells were stimulated with nucleic acids and extracted RNA was sequenced with Illumina HiSeq and showed that stressed keratinocytes express typical NKG2D ligands MICA/B and ULBP2. This study provides first evidence that NKG2D is present in CDLE and SCLE skin lesions and could be relevant for cytotoxicity in IFN-driven skin lesions with upregulated innate immune response pathways present in CLE. It could furthermore play a role in CLE inflammation promoted by keratinocytes under cell stress.

It is not yet entirely clear what is the relevance of skin symptoms and what clinical implications are related to their appearance in COVID‐19 patients. We describe two cases of COVID‐19‐associated pneumonia, which presented skin manifestations in advanced stage of illness, when nasopharyngeal swabs became negative for SARS‐CoV‐2. The first case presented erythematous, maculopapular lesions; the second developed petechial, vesicular and blood‐encrusted lesions on the limbs. Histopathology documented perivascular lymphocytic infiltrates, with prevalent CD4+ T‐cells in both patients. The research of SARS‐CoV‐2 in tissues with real time RT‐PCR was negative. Basal keratinocytes displayed C4d deposits in one case, who developed laboratory signs indicative of a procoagulative condition at the same time as the skin rash. Skin manifestations during SARS‐CoV‐2 infection seem to be clinically relevant and further studies are necessary to assess if they are linked to systemic complications, lack of viral clearance or cascades of immune responses induced by the virus, even in patients affected by mild pneumonia.

Background Alopecia areata (AA) is a common cause of hair loss. It is mediated by T lymphocytes. Scalp biopsy findings in AA differ according to the disease phase and activity. Objectives To study the cellular infiltrate in the transverse section of scalp biopsy of AA at different disease stages and in relation to disease activity. Methods The study was performed on 40 subjects with AA. A 4-mm punch biopsy was obtained from an AA scalp lesion. Biopsies were sectioned horizontally; 2 anatomical levels were studied (mid dermal and deep dermal levels). Results Ninety-five percent of AA showed noncicatrical alopecia. A significant relation was found between the course of AA and the terminal:vellus ratio. Peribulbar lymphocytic infiltration was seen in 70% of cases. Mast cells were observed in 87.5% of cases, including fibrous tract and around the arrector pili muscles. Eosinophils were detected in the scalp biopsy of 22.5% of cases. Course and activity of AA were significantly related to the peribulbar lymphocytic cell infiltration but not to mast cells and eosinophils. Conclusion Although a peribulbar lymphocytic infiltrate is the classical finding of AA, it is absent in the chronic phase. Mast cells are commonly found in the scalp biopsy of AA and could explain the potential therapeutic effect of antihistamines.

We documented fetal death associated with intrauterine transmission of severe acute respiratory syndrome coronavirus 2. We found chronic histiocytic intervillositis, maternal and fetal vascular malperfusion, microglial hyperplasia, and lymphocytic infiltrate in muscle in the placenta and fetal tissue. Placenta and umbilical cord blood tested positive for the virus by PCR, confirming transplacental transmission.

Lichenoid granulomatous dermatitis (LGD) is a histopathologic pattern with a band-like lymphocytic infiltrate, typical of lichenoid dermatitis, combined with dermal histiocytes and granulomatous inflammation. Prior reports have described cases of LGD caused by non-tuberculous mycobacteria, with evidence of intralesional acid-fast bacilli or mycobacterial DNA. Herein, we report a patient with pulmonary and extrapulmonary Mycobacterium tuberculosis infection who developed LGD. No evidence of M. tuberculosis was detected within the cutaneous lesions, suggesting a potential delayed-type hypersensitivity reaction to tuberculosis.

Gene fusions resulting in oncogenic activation of various receptor tyrosine kinases, including NTRK1-3, ALK, and RET, have been increasingly recognized in soft tissue tumors (STTs), displaying a wide morphologic spectrum and therefore diagnostically challenging. A subset of STT with NTRK1 rearrangements were recently defined as lipofibromatosis-like neural tumors (LPFNTs), being characterized by mildly atypical spindle cells with a highly infiltrative growth in the subcutis and expression of S100 and CD34 immunostains. Other emerging morphologic phenotypes associated with kinase fusions include infantile/adult fibrosarcoma and malignant peripheral nerve sheath tumor-like patterns. In this study, a large cohort of 73 STT positive for various kinase fusions, including 44 previously published cases, was investigated for the presence of an LPFNT phenotype, to better define the incidence of this distinctive morphologic pattern and its relationship with various gene fusions. Surprisingly, half (36/73) of STT with kinase fusions showed at least a focal LPFNT component defined as >10%. Most of the tumors occurred in the subcutaneous tissues of the extremities (n = 25) and trunk (n = 9) of children or young adults (

Purpose In 2012, four patients with multiple asymptomatic, indolent, unilateral, choroidal lesions were described. We suspected benign-behaving lymphocytes infiltrating the choroid. This article expands the number of patients and duration of follow-up and speculates further on the etiology. Although histopathologic confirmation of these lesions is still unknown, the natural course of these patients is excellent and should be distinguished from aggressive choroidal lymphoma. Methods To qualify for the study, the patients had to meet the following criteria: 1) Patients collected had asymptomatic choroidal infiltrates as demonstrated in the figures; 2) absence of vitreous cells; 3) no evidence of concomitant systemic malignancy; 4) no systemic inflammatory diseases, including sarcoidosis; 5) no birdshot chorioretinopathy; 6) no conjunctival or orbital lesions; and 7) advanced multimodal imaging and clinical follow-up were performed. Results There were 11 eyes of 11 patients seen. Follow-up ranged from 4 months to 12 years and 1 month (mean 50.2 months; median 24 months). Systemic workup was unrevealing. No patients in this cohort developed systemic, conjunctival, orbital, or vitreoretinal lymphoma or inflammatory disease. No patients developed symptoms or vision loss. Conclusion This entity is an indolent choroidal infiltrative disease. It resembles some cases of choroidal lymphoma and may represent an indolent lymphocytic infiltrate.

Hyperkeratosis lenticularis perstans (HLP), or Flegel's disease (FD), is a rare disorder of keratinization first described in 1958 by Flegel. HLP is characterized by asymptomatic small papules distributed symmetrically on the dorsal feet and lower part of the legs. It typically presents in the fourth or fifth decade of life. FD has been reported more commonly in women, and little is known about the pathogenesis of this rare dermatosis. Histological examination is mandatory to confirm the diagnosis, and the characteristic features are: focal compact hyperkeratosis, thinned stratum malpighii, epidermal atrophy, and a dense, band-like lymphocytic infiltrate in the papillary dermis. The treatment of FD is challenging, and a fully effective standard therapy does not exist. We report four cases of HLP that have been diagnosed at the Dermatology Unit of IRCCS Ca' Granda Ospedale Maggiore Policlinico in Milan, Italy, and a literature review is enclosed.

Purpose Immune checkpoint inhibitors have recently been approved by the US FDA as first and/or second line therapy in a subset of cancer types. Recent evidence suggests that the quantity of tumor infiltrating lymphocytes (TILs) influences the likelihood of response to immune checkpoint inhibitors. Here, we set out to assess the density of CD8+ lymphocytes in a wide range of different cancer types and subtypes. Methods The density of CD8+ lymphocytes was compared across different cancer types using tissue microarrays (TMAs) composed of up to 50 tumor samples each from 84 different cancer types and subtypes. In total 2652 cancers and 608 normal tissues were successfully analyzed by CD8 immunohistochemistry followed by automated image analysis of digitized slides. Results We found that the median CD8+ lymphocyte counts ranged from 6 cells/mm2 in pleomorphic adenoma up to 1573 cells/mm2 in Hodgkin’s lymphoma. The CD8 counts were generally lower in normal tissues compared to cancer tissues. Blood vessels of the spleen were the only non-lymphatic tissue staining positive for CD8. Tumor types approved for checkpoint inhibitor therapy, including malignant melanoma (81), muscle invasive urothelial carcinoma (119), small cell lung cancer (120), clear cell renal cell cancer (153), squamous cell carcinoma (189) and adenocarcinoma of the lung (328) as well as Hodgkin’s lymphoma (1573) were all ranking among the upper half of our list. Comparably high CD8 densities (median cells/mm2) were also found in several rare and aggressive cancer types including Merkel cell carcinoma (70), angiosarcoma (95), anaplastic thyroid cancer (156) and embryonal carcinoma of the testis (186). In 73 of the 84 analyzed cancer types, the highly variable CD8 counts occasionally exceeded the average CD8 count of tumors for which checkpoint inhibitors have been approved. Conclusion These data support the concept that among most tumor types at least some individual cancers may benefit from treatment with immune checkpoint inhibitors.

Background Macular lymphocytic arteritis most commonly presents as hyperpigmented macules on the lower limbs. The pathogenesis of this disease is still unclear and there is an ongoing debate regarding whether it represents a new form of cutaneous vasculitis or an indolent form of cutaneous polyarteritis nodosa. Objective To describe clinical, histopathological, and laboratory findings of patients with the diagnosis of macular lymphocytic arteritis. Methods A retrospective search was conducted by reviewing cases followed at the Vasculitis Clinic of the Dermatology Department, School of Medicine, University of Sao Paulo, between 2005 and 2017. Seven patients were included. Results All cases were female, aged 9–46 years, and had hyperpigmented macules mainly on the legs. Three patients reported symptoms. Skin biopsies evidencing a predominantly lymphocytic infiltrate affecting arterioles at the dermal subcutaneous junction were found, as well as a typical luminal fibrin ring. None of the patients developed necrotic ulcers, neurological damage, or systemic manifestations. The follow-up ranged from 18 to 151 months, with a mean duration of 79 months. Study limitations This study is subject to a number of limitations: small sample of patients, besides having a retrospective and uncontrolled study design. Conclusions To the best of the authors’ knowledge, this series presents the longest duration of follow-up reported to date. During this period, none of the patients showed resolution of the lesions despite treatment, nor did any progress to systemic vasculitis. Similarities between clinical and skin biopsy findings support the hypothesis that macular lymphocytic arteritis is a benign, incomplete, and less aggressive form of cutaneous polyarteritis nodosa.

Neuronal/mixed glioneuronal tumors are central nervous system neoplasms composed of neoplastic neuronal cell components or a mixture of glial and neuronal elements. They occur in cerebral hemispheres, posterior fossa, and spinal cord. Compared with other tumors at these locations, diencephalic neuronal/glioneuronal tumors are very rare and therefore not well characterized. We hereby performed clinicopathologic evaluation on 10 neuronal/glioneuronal tumors arising from the diencephalic region. Morphologically, these tumors resemble their histologic counterparts in other locations, except that lymphocytic infiltrates and microcalcifications are more common than Rosenthal fibers or eosinophilic granular bodies. The BRAFV600 mutation rate is 75%. Given the high percentage of samples being small biopsy specimens, the subtle histologic features and molecular findings greatly aided in establishing the pathologic diagnosis in several cases. At a median follow-up of 42 months, 71% of the tumors demonstrated radiological recurrence or progression, with median progression-free survival of 18 months. Recurrence/progression is observed in tumors across different histologic subtypes, necessitating additional therapies in 56% of the cases. Despite their bland histology, diencephalic neuronal/glioneuronal tumors are not clinically indolent. Their frequent recurrences warrant a close follow-up, and the prevalent BRAF mutation makes MAPK pathway inhibition a plausible treatment option when conventional therapies fail.

Background and Objectives: Ovarian cancer is the leading cause of death among gynecological tumors. PD-1/PD-L1 immunoregulatory mechanism is activated in ovarian cancers. Lymphocyte infiltration is a significant factor that affects its expression. We analyzed the correlation between localization of lymphocytic infiltrate and PD-L1 expression in epithelial ovarian tumors. Materials and Methods: PD-L1 expression was analyzed in 328 subjects, 122 with epithelial ovarian carcinoma, 42 with atypical proliferative tumor, and 164 with benign epithelial ovarian tumor. Expression in central and invasive tumor parts in epithelial ovarian carcinoma was combined with the most pronounced lymphocyte reaction. Immunohistochemical analysis was performed using the tissue microarray and correlated with a set of histopathology parameters. Results: PD-L1 expression was most prominent in epithelial ovarian carcinoma with different levels of expression observed between invasive and central tumor segments. A high level of PD-L1 expression on tumor cells was more frequently present in the invasive than in the central tumor parts (p < 0.001) only in high-grade serous ovarian carcinoma (HGSC). There was no significant correlation between peritumoral lymphocytic infiltrate and PD-L1 expression regardless of tumor segment. In the central tumor parts of HGSC, there was a correlation of intratumoral lymphocytic infiltrate with a higher level of PD-L1 expression (p = 0.003). Conclusions: The most prominent PD-L1 expression was observed in the invasive tumor parts of HGSC. Only the central parts of the HGSC exhibited significant PD-L1 expression in association with considerable intratumoral lymphocytic infiltrate.

Aims Intracranial myxoid mesenchymal tumors (IMMTs) with fusions between EWSR1/FUS and CREB transcription factors have morphologic overlap with myxoid angiomatoid fibrous histiocytoma (mAFH) and myoepithelial tumor/carcinoma (MET/MEC). We aimed to study the clinicopathologic and genetic spectrum of extracranial IMMT-like tumors and their relationships with mAFH and MET/MEC. Methods Twelve extracranial tumors harboring EWSR1/FUS-CREB fusions across different histologic groups were characterized using RNA sequencing, FISH and/or RT-PCR. Results There were 4 IMMT-like neoplasms, 3 MET/MECs, and 5 mAFHs from the tibia (n=1), oral cavity (n=2), and soft tissues (n=9; 5 in the extremities), harboring EWSR1-ATF1 in 4 cases, FUS-CREM and EWSR1-CREM in 2 each, and EWSR1-CREB1 in 2. Multinodular growth, reticular/cording/trabecular arrangements, myxocollagenous matrix, and lymphocytic infiltrates variably prevailed among the 3 groups. mAFHs were characterized by cells with syncytial cytoplasm. IMMT-like neoplasms and MET/MECs shared cells with distinct boundaries, but only MET/MECs expressed GFAP and/or S100. MUC4 and ALK were expressed in some IMMT-like neoplasms (2/4; 2/4) and mAFH (2/5; 1/5). Pan-TRK reactivity was observed in two IMMT-like neoplasms with upregulated NTRK3 mRNA and one MEC. Local recurrences, typically ≥ 12 months postoperatively, developed in 2/3 IMMT-like neoplasms, 1/2 MET/MECs, and 0/4 mAFHs with follow-up. No definite associations were found between fusion types and histology, immunoprofile or outcome. Conclusions We demonstrated the similarities and differences among 3 extracranial myxocollagenous tumor groups sharing EWSR1/FUS-CREB fusions. Oral IMMT-like neoplasms harboring FUS-CREM or EWSR1-ATF1 and FUS-CREM-positive

Lung adenocarcinoma (LUAD), the most common non‐small‐cell lung cancer, is characterized by a dense lymphocytic infiltrate, which indicates that the immune system plays an active role in the development and growth of this cancer. However, no investigations to date have proposed robust models for predicting survival outcome for patients with LUAD in terms of tumour immunology. A total of 761 LUAD patients were included in this study, in which the database of The Cancer Genome Atlas (TCGA) was utilized for discovery, and the Gene Expression Omnibus (GEO) database was utilized for validation. Bioinformatics analysis and R language tools were utilized to construct an immune prognostic model and annotate biological functions. Lung adenocarcinoma showed a weakened immune phenotype compared with adjacent normal tissues. Immune‐related gene sets were profiled, an immune prognostic model based on 2 immune genes (ANLN and F2) was developed with the TCGA database to distinguish cases as having a low or high risk of unfavourable prognosis, and the model was verified with the GEO database. The model was prognostically significant in stratified cohorts, including stage I‐II, stage III‐IV and epidermal growth factor receptor (EGFR) mutant subsets, and was considered to be an independent prognostic factor for LUAD. Furthermore, the low‐ and high‐risk groups showed marked differences in tumour‐infiltrating leucocytes, tumour mutation burden, aneuploidy and PD‐L1 expression. In conclusion, an immune prognostic model was proposed for LUAD that is capable of independently identifying patients at high risk for poor survival, suggesting a relationship between local immune status and prognosis.

Granulomatous pigmented purpuric dermatosis clinically manifests as hyperpigmented maculae and petechiae, predominantly on the lower extremities. Histopathologically, it is characterized by a lymphocytic infiltrate in the upper dermis, extravasated erythrocytes, and hemosiderin deposits. There is an infrequent variant called granulomatous pigmented purpuric dermatosis, which histologically is characterized by the presence of non-necrotizing granulomas associated with the classic findings of other pigmented purpuric dermatoses. It more frequently affects middle-aged women of Asian origin, and predominantly on the lower extremities. The authors present the case of a female patient with granulomatous pigmented purpuric dermatosis on the lower extremities with blaschkoid distribution.

Rosai-Dorfman disease (RDD) is an uncommon disorder, characterized by an atypical expansion of histiocytes which classically shows emperipolesis and immunoreactivity with S-100 protein. RDD affects the lymph nodes as well as extranodal sites; however, RDD of the breast is exceptionally rare. Herein, we describe the histopathologic features of 22 cases of RDD occurring in the breast, with an emphasis on the differential diagnosis. All cases were notable for an exuberant lymphocytic infiltrate with and without germinal center formation, and the majority (19/22) showed numerous plasma cells: 5 to 132/high-power field (HPF). IgG and IgG4 immunohistochemical stains were available for 13 cases; in no instance were criteria for IgG4-related sclerosing disease met, though in a single case the IgG4/IgG ratio was increased to 25%. Sclerosis was present in the majority of cases (18/22), and was frequently prominent. RDD cells showing emperipolesis were present in all cases (22/22), and ranged from rare (1/50 HPF) to numerous (50/50 HPF). Two of the cases in our series were initially misdiagnosed as inflammatory myofibroblastic tumor and plasma cell mastitis with granulomatous inflammation. As emperipolesis can be indistinct, the presence of stromal fibrosis and a prominent lymphoplasmacytic inflammatory infiltrate should prompt a careful search for the characteristic histiocytes, which can be aided by the use of S-100 immunohistochemistry.

Long-term survivors of bronchopulmonary dysplasia develop chronic obstructive lung disease. Herein we report in vivo histopathology from bronchial biopsies of 3 adolescent survivors of severe bronchopulmonary dysplasia. Thickened basement membranes with lymphocytic infiltrates and signs of immature neoangiogenesis in the absence of T-helper lymphocytes or eosinophils suggest the presence of an ongoing active airway process.

Background Approximately two thirds of patients with localized triple-negative breast cancer (TNBC) harbor residual disease (RD) after neoadjuvant chemotherapy (NAC) and have a high risk-of-recurrence. Targeted therapeutic development for TNBC is of primary significance as no targeted therapies are clinically indicated for this aggressive subset. In view of this, we conducted a comprehensive molecular analysis and correlated molecular features of chemorefractory RD tumors with recurrence for the purpose of guiding downstream therapeutic development. Methods We assembled DNA and RNA sequencing data from RD tumors as well as pre-operative biopsies, lymphocytic infiltrate, and survival data as part of a molecular correlative to a phase II post-neoadjuvant clinical trial. Matched somatic mutation, gene expression, and lymphocytic infiltrate were assessed before and after chemotherapy to understand how tumors evolve during chemotherapy. Kaplan-Meier survival analyses were conducted categorizing cancers with TP53 mutations by the degree of loss as well as by the copy number of a locus of 18q corresponding to the SMAD2, SMAD4, and SMAD7 genes. Results Analysis of matched somatic genomes pre-/post-NAC revealed chaotic acquisition of copy gains and losses including amplification of prominent oncogenes. In contrast, significant gains in deleterious point mutations and insertion/deletions were not observed. No trends between clonal evolution and recurrence were identified. Gene expression data from paired biopsies revealed enrichment of actionable regulators of stem cell-like behavior and depletion of immune signaling, which was corroborated by total lymphocytic infiltrate, but was not associated with recurrence. Novel characterization of TP53 mutation revealed prognostically relevant subgroups, which were linked to MYC-driven transcriptional amplification. Finally, somatic gains in 18q were associated with poor prognosis, likely driven by putative upregulation of TGFß signaling through the signal transducer SMAD2. Conclusions We conclude TNBCs are dynamic during chemotherapy, demonstrating complex plasticity in subclonal diversity, stem-like qualities, and immune depletion, but somatic alterations of TP53/MYC and TGFß signaling in RD samples are prominent drivers of recurrence, representing high-yield targets for additional interrogation. Electronic supplementary material The online version of this article (10.1186/s13058-019-1171-7) contains supplementary material, which is available to authorized users.

Flagellate erythema is a distinctive eruption characterized by "whip-like" linear or curvilinear streaks and plaques, occurring mainly on the trunk. It has classically been described in 2 disparate clinical settings: chemotherapy with bleomycin and ingestion of mushrooms (most commonly Shiitake mushrooms). Most of the literature comprises single case reports, often with minimal histological description of rather nonspecific features. We describe in detail the histological features of 3 cases of flagellate erythema (2 related to bleomycin therapy and one related to ingestion of mushrooms) and review the findings described in the literature to define the spectrum of histological changes encountered in this eruption. Our 3 cases showed mild epidermal changes, with spongiosis and variable interface inflammation. All 3 showed a relatively prominent dermal lymphohistiocytic infiltrate, with features suggestive of a lymphocytic vasculopathy extending to at least the mid-reticular dermis. Eosinophils were a prominent component of the inflammatory infiltrate in 2 cases. Our review of the literature identified a total of 45 publications, representing reports of 46 patients, containing histological information. As well as bleomycin- and mushroom-related cases, similar eruptions have been reported in the context of connective tissue disease and other drugs. Although cases related to connective tissue disease show features of the underlying condition, cases secondary to drugs or mushrooms predominantly show features compatible with common patterns of exanthematous/morbilliform drug reaction. In particular, subtle spongiosis and/or interface dermatitis combined with a dermal lymphocytic infiltrate that includes increased numbers of eosinophils is a common finding. Features of a lymphocytic vasculopathy may be seen in a subset of these cases.

ObjectivePrimary Sjögren syndrome (SS) is characterized by a focal lymphocytic infiltrate in exocrine glands. We describe patients who lacked this key feature.Methods.We evaluated patients with sicca in a comprehensive clinic at which medical, dental, and ophthalmological examinations were performed. All subjects underwent a minor salivary gland biopsy with focus score calculation. Extraglandular manifestations were also determined. We categorized subjects as high, intermediate, or low in terms of expression of interferon (IFN)-regulated genes.Results.About 20% (51 of 229, 22%) of those classified as having primary SS had a focus score of zero. Compared to those with anti-Ro positivity and a focus score > 1.0, the patients with focus score of zero (who by classification criteria must be anti-Ro–positive) were statistically less likely to have anti-La (or SSB) and elevated immunoglobulin, as well as less severe corneal staining. The focus score zero patients were less likely to have elevated expression of IFN-regulated genes in peripheral blood mononuclear cells than anti-Ro–positive SS patients with a focal salivary infiltrate.Conclusion.There are only a few clinical differences between patients with primary SS with focus score zero and those with both anti-Ro and a focus score > 1.0. The small subset of focus score zero patients tested did not have elevated expression of IFN-regulated genes, but did have systemic disease. Thus, extraglandular manifestations are perhaps more related to the presence of anti-Ro than increased IFN. This may have relevance to pathogenesis of SS.

Spermatocytic seminoma (or, alternatively, spermatocytic tumor) of the testis is rare and errors in pathologic diagnosis are still made. As it has a good prognosis, except when it, rarely, undergoes sarcomatous transformation, accurate diagnosis and differentiating it from usual seminoma and other malignant neoplasms such as lymphoma are crucial. To potentially contribute information of diagnostic aid we reviewed the largest series of cases reported to date to characterize in detail their histologic spectrum. The patients ranged from 30 to 81 years (average, 52 y); 30% were in the fourth decade. The neoplasms ranged from 1.4 to 15 cm (average, 5.7 cm). Most were fleshy, soft, and often lobulated and 11 were edematous or mucoid. Low-power microscopic examination either showed a predominant multinodular (43/85) or diffuse (42/85) pattern. All tumors had the classic "tripartite" cellular population. Five tumors showed a relatively monomorphic population of the intermediate cell type with vesicular chromatin and very prominent nucleoli, at least focally. Two tumors underwent sarcomatous transformation, with 1 having a focus of atypical cartilage. Additional findings, some not previously reported or emphasized, included: (1) frequent edema fluid (87%) often causing spaces, both follicle-like (24%) and irregular (39%), a finding seen in some usual seminomas (but less frequently) and rarely seen in lymphomas; (2) tumor nodules showing partial rims of fibrin (20%); (3) a distinctive arrangement of connecting tumor islands (19%); (4) prominent lymphocytic infiltrates (8%); (5) granulomatous inflammation (1%); (6) striking mitotic activity and apoptosis; (7) intratubular spread (64%); and (8) vessel invasion (11%) and necrosis (8%). Awareness of these aspects may be of importance either at the time of intraoperative evaluation or on final pathologic analysis and help avoid significant errors in diagnosis.

Multinucleate cell angiohistiocytoma (MCAH) is an uncommon fibrohistiocytic disorder that usually presents as a localized solitary papule or multiple grouped papules. Generalized presentation is very rare with less than 20 cases reported in the literature. In this article, we present histopathological and immunohistochemical studies of 10 lesions from a patient with generalized MCAH. In all lesions, the histopathological changes were confined to a discrete zone of the superficial dermis that consisted of (1) an increase in the number of capillary-sized vessels with thickened walls, (2) presence of oval to dendritic spindle cells and stellate hyperchromatic multinucleated cells, (3) fibrosis marked by compact collagen, (4) hypertrophy and hyperplasia of small nerve fibers, and (5) a moderately dense lymphocytic infiltrate. The entire population of the cellular component including the multinucleated cells stained for CD10, whereas a subpopulation of the mononuclear spindle cells stained for factor XIIIa and CD68. CD34 highlighted only the blood vessels. The results confirm that the multinucleated cells lack expression of CD68 and factor XIIIa and that CD10 may be used to highlight the entire cellular component. The rarely reported hypertrophy and hyperplasia of nerve fibers in MCAH may be a common finding as it was observed in all 10 lesions.

Reports of chilblain-like lesions (CLL) coinciding with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection have been described in the literature, but this phenomenon has not been critically summarized. The aim of this paper is to summarize reports of CLL coinciding with SARS-CoV-2 infection to clarify the prevalence, clinical relevance, and prognostic value of these lesions. A literature search was conducted using the Embase, Pubmed, and Scopus databases from December 2019 to June 16, 2020 using the search terms (“COVID-19” OR “coronavirus” OR “2019-nCoV” OR “SARS-CoV-2”) AND (“chilblain-like” OR “COVID toes” OR “acral”). Papers that described skin changes in patients with suspected or confirmed COVID-19 were included. A total of 31 papers were summarized, representing 813 cases of CLL. Available data suggests an equal gender distribution, mean age of 21 years, and median age of 14 years. Mild extracutaneous symptoms were reported in 53% of cases and 47% were asymptomatic. CLL occurred an average of 16 days after extracutaneous symptoms. Patients with CLL were positive for SARS-CoV-2 in 15% of cases. Lesions were mainly described as asymptomatic and/or pruritic erythematous to violaceous acral macules and plaques. Partial or complete resolution occurred in 85% of cases in a mean of 13 days. The most common histologic findings were perivascular and perieccrine superficial and deep lymphocytic infiltrates. Although a causal relationship between CLL and SARS-CoV-2 has not been confirmed, the temporal association and 15% positive SARS-CoV-2 rate in affected individuals should not be ignored.

One-hundred fourty pure dysgerminomas were evaluated with particular focus on the microscopic features as seen in 125 cases with available slides. The patients ranged from 8 to 59 years of age (mean, 24.1 y). The tumors, bilateral in 4% of the cases and with a mean tumor diameter of 13 cm, were typically soft, lobulated, homogeneous, and creamy white to tan to yellow but necrosis was found in 13%, hemorrhage in 20%, and focal cystic change in 15%. On microscopic examination, the patterns and other notable features encountered, including their frequency, were as follows: an alveolar pattern resulting from delicate fibrovascular septa (51%), diffuse (33%), macronodular (14%), insular (26%), cords (28%), solid tubular (17%), microspaces (sometimes simulating glands) (12%), follicle-like spaces (5%), prominent fibrous bands (65%), stromal edema (56%), stromal luteinization (9%), granulomatous infiltrate (46%), lymphocytic infiltrate (100%), Langhans cell type giant cells (35%), syncytiotrophoblast giant cells (6%), prominent population of cells with pale to clear cytoplasm (73%), cells with amphophilic to eosinophilic cytoplasm (53%) and vacuolated occasionally signet ring-like cells (7%). Various constellations of the above findings often resulted in an appearance different from that usually portrayed in the literature and certain tumors of very different nature being in the differential such as undifferentiated carcinoma not otherwise specified, small cell carcinoma of hypercalcemic type, and malignant lymphoma. The correct diagnosis can be arrived at by considering the usual relative youth of the patient, often rather characteristic gross features, and most crucially careful attention to the microscopic features and awareness of variant morphologic findings. Those that are particularly problematic based on this study are diffuse growth with inconspicuous fibrovascular septa, macronodules, cords, solid tubular formations, spaces ranging from small to large, and mimicking glands or follicles, prominent fibrous to edematous stroma, and cells with amphophilic to eosinophilic cytoplasm. According to the degree of difficulty and confidence of the interpreter, well-known immunohistochemical features of dysgerminoma, which largely differ from those of other neoplasms in the differential, will aid if felt indicated.

In this systematic review, we anticipated in summarizing clinical features, histopathological hallmarks, and possible pathology behind the maculopapular skin eruptions occurring in Covid‐19 patients. A literature search was executed using MEDLINE/PubMed and Embase databases for articles published till 20 November 2020. All eligible articles including observational studies, case reports, and case series reporting the maculopapular skin lesion in Covid‐19 patients were included. Data were obtained for 354 Covid‐19 patients presenting with maculopapular lesions from 40 studies. The mean age of these patients was 53 years, and with 42% of them being male. These maculopapular lesions differed considerably in terms of distribution and appearance, ranging from diffuse erythematous maculopapular lesions to scattered erythematous macules coalescing into papules to maculopapular lesions in plaques. The mean duration of the lesion was 8 days. These lesions were frequently localized on trunks and extremities. Superficial perivascular dermatitis with lymphocytic infiltrate was a histopathological hallmark of these lesions. As these skin lesions may have a possible association with diagnosis, management, prognosis, and severity of the disease, all health practitioners need to be well acquainted with these Covid‐19 skin lesions. Also, in the middle of this worldwide pandemic, early identification of this eruption may help manage this infection's further spread.

Hip implants are a successful solution for osteoarthritis; however, some individuals with metal-on-metal (MoM) and metal-on-polyethylene (MoP) prosthetics develop adverse local tissue reactions (ALTRs). While MoM and MoP ALTRs are presumed to be delayed hypersensitivity reactions to corrosion products, MoM- and MoP-associated ALTRs present with different histological characteristics. We compared MoM- and MoP-associated ALTRs histopathology with cobalt and chromium levels in serum and synovial fluid. We analyzed the gene expression levels of leukocyte aggregates and synovial fluid chemokines/cytokines to resolve potential pathophysiologic differences. In addition, we classified ALTRs from 79 patients according to their leukocyte infiltrates as macrophage-dominant, mixed, and lymphocyte-dominant. Immune-related transcript profiles from lymphocyte-dominant MoM- and MoP-associated ALTR patients with perivascular lymphocytic aggregates were similar. Cell signatures indicated predominantly macrophage, Th1 and Th2 lymphocytic infiltrate, with strong exhausted CD8+ signature, and low Th17 and B cell, relative to healthy lymph nodes. Lymphocyte-dominant ALTR-associated synovial fluid contained higher levels of induced protein 10 (IP-10), interleukin-1 receptor antagonist (IL-1RN), IL-8, IL-6, IL-16, macrophage inflammatory protein 1 (MIP-1α), IL-18, MCP-2, and lower cell-attracting chemokine levels, when compared with prosthetic revisions lacking ALTRs. In addition, the higher levels of IP-10, IL-8, IL-6, MIP-1α, and MCP-2 were observed within the synovial fluid of the lymphocyte-dominant ALTRs relative to the macrophage-dominant ALTRs. Not all cytokines/chemokines were detected in the perivascular aggregate transcripts, suggesting the existence of other sources in the affected synovia. Our results support the hypothesis of common hypersensitivity pathogenesis in lymphocyte-dominant MoM and MoP ALTRs. The exhausted lymphocyte signature indicates chronic processes and an impaired immune response, although the cause of the persistent T-cell activation remains unclear. The cytokine/chemokine signature of lymphocyte-dominant-associated ATLRs may be of utility for diagnosing this more aggressive pathogenesis.

A 4-year-old girl presented with a 2-month history of round, hypopigmented, slightly scaly patches measuring 1-6 cm and encircled by an erythematous halo, first appearing on the lower limbs then spreading to the whole body. Three biopsies were taken as the condition progressed, each showing a lymphocytic infiltrate affecting a medium-sized artery at the dermal-subcutaneous junction, with a concentric fibrin ring. These findings are characteristic of lymphocytic thrombophilic arteritis (LTA). The young age of our patient and the type of skin lesions she developed make this an atypical presentation of LTA, which usually manifests as hyperpigmented macules on the lower extremities, predominantly in dark-skinned women.

T-lymphocytic enteral leiomyositis (T-lel) is a rare disorder causing chronic intestinal pseudo-obstruction (CIPO), with cases predominantly being reported in the field of veterinary and pediatric medicine. Here, we present a case of T-lel-associated CIPO in an adult female, who initially presented with a paralytic ileus 2 weeks after a common gastroenteritis. The histological diagnosis was established through full-thickness bowel biopsy, exhibiting a dense lymphocytic infiltrate in the lamina muscularis of the intestinal wall. This case shows that T-lel can be a cause of chronic intestinal pseudo-obstruction not only in children but also in adults. A subsequent induction of an immunosuppressive therapy with steroids, azathioprine, and ultimately TNF-alpha-inhibiting antibodies led to a slow recovery and stable disease.Die T-lymphozytäre enterale Leiomyositis (T-lel) ist eine seltene Erkrankung, die zu einer chronischen intestinalen Pseudoobstruktion (CIPO) führen kann. Die meisten dieser seltenen Fälle sind bei Kindern und in der Veterinärmedizin beschrieben. Hier berichten wir über den Fall einer 42-jährigen Patientin, die sich 2 Wochen nach gastroenterischen Beschwerden mit der Klinik eines paralytischen Ileus vorstellte. Nachdem eine weitreichende Diagnostik mittels laboranalytischer, endoskopischer und radiologischer Verfahren keine wegweisenden Befunde erbrachte, erfolgte die Durchführung einer Dünndarm-Vollwandbiopsie, woraufhin histologisch die Diagnose einer T-lymphozytären Leiomyositis gestellt werden konnte. Eine immunsuppressive Therapie mit initial Prednisolon und Azathioprin wurde aufgrund unzureichenden klinischen Ansprechens auf Adalimumab umgestellt, woraufhin letztlich eine Stabilisierung der Erkrankung und eine Verbesserung der Symptomatik erreicht werden konnten.

Sebaceous lymphadenoma is a rare salivary gland neoplasm most commonly occurring in the sixth to eighth decades of life. Cross sectional imaging typically demonstrates a multicystic expansile mass, most commonly occurring in the parotid gland, where the radiographic differential diagnosis would include Warthin tumor in this location and age group. Ultimately, the diagnosis is confirmed with the histopathologic findings of tubuloglandular epithelial profiles with sebaceous differentiation and cystic change set within a dense, benign lymphocytic infiltrate. These features are exemplified in this sine qua non radiology-pathology correlation article.

BACKGROUND Venous aneurysms are long-term complications of arteriovenous fistula (AVF) for hemodialysis with an estimated incidence rate of around 5-6%. The purpose of our study is to investigate the role of immunosuppressive therapy in the development of AVF aneurysms in renal transplant patients, and to determine whether AVF closure following transplantation is necessary. METHODS Forty-six patients with symptomatic venous AVF aneurysms underwent ligation and resection of their fistulas between January 2013 and January 2020. Immunohistochemical expression of CD3, CD4, and CD8 was assessed on the surgical specimens to characterize lymphocytic infiltrate in the aneurysm wall. Patients were subdivided into "Group A"-kidney transplant patients undergoing immunosuppressive therapy which was comprised of 39 patients and "Group B"-patients who had not undergone kidney transplant which was comprised of 7 patients. The 2 groups did not significantly differ in age, sex nor risk factors for aneurysms. RESULTS Group A showed a significantly higher aneurysm diameter (P < 0.0001), mean flow (P < 0.0001) and required a longer duration of surgery (P = 0.0007). A CD3+ lymphocytic infiltrate was significantly more common in Group A than in the Group B (90% vs 29%; P < 0.001). No significant differences in localization (adventitia, media or intima) and type (CD4+ vs CD8+) of lymphocytes were found between the 2 groups. CONCLUSION AVF venous aneurysms were significantly larger and with a more intense T-lymphocytic infiltrate in patients undergoing immunosuppressive therapy. This finding suggests that immunosuppressive therapy plays a role in aneurysm formation, supporting the need for AVF closure in patients with an estimated low risk of rejection.

Background Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by a lymphocytic infiltrate in salivary glands driving to epithelial damage. The pSS patients present heterogenic clinical and serological characteristics. This heterogenicity could be due to the cytokine microenvironment. Cytokine levels have been analyzed and reported individually, showing controversial results; for that reason, we considered essential to evaluate a cluster of cytokines and relate them with antibody levels and clinical characteristics to find pSS subgroups. Methods Ninety‐nine pSS patients, diagnosed by the 2016 ACR/EULAR classification criteria, and 76 control subjects (CS) were included. Cytokine quantification was performed by Multiplex assay. Principal component analysis (PCA) was realized, and the K‐mean test was used to identify clusters/groups. Groups were analyzed by the Kruskal‐Wallis test and the Bonferroni test. Results Higher IFN‐γ, IL‐17F, IL‐21, IL‐23, IL‐4, and IL‐31 levels were observed in pSS patients in comparison with control subjects. PCA analysis showed three groups. The severe group was characterized by higher cytokine concentrations as well as an increase in clinical parameters such as antibody levels, damage index score, and others. The moderate group presented intermediate severity; meanwhile, the mild group presented the lowest severity. Conclusion Cluster analysis revealed three groups that were different in cytokine levels and clinical parameters in which the mild group was defined by lower severity, the moderate group with intermediate severity, and the severe group with higher severity. This analysis could help subclassify the primary Sjögren syndrome patients for a better understanding of the clinical phenotype that impacts the treatment approach., Principal component analysis of 14 cytokines was realized to determine the cytokine groups in primary Sjögren´s syndrome patients. The mild group was characterized by less severity of the disease with low cytokine levels and fewer clinical parameters; the moderate group included patients with intermediate severity, presented higher cytokine levels than the mild group but less than severe group. Patients of the severe group showed higher severity, higher cytokine levels, and clinical parameters.

Purpose For optimal management of ductal carcinoma in situ (DCIS), reproducible histopathological assessment is essential to distinguish low-risk from high-risk DCIS. Therefore, we analyzed interrater reliability of histopathological DCIS features and assessed their associations with subsequent ipsilateral invasive breast cancer (iIBC) risk. Methods Using a case-cohort design, reliability was assessed in a population-based, nationwide cohort of 2767 women with screen-detected DCIS diagnosed between 1993 and 2004, treated by breast-conserving surgery with/without radiotherapy (BCS ± RT) using Krippendorff’s alpha (KA) and Gwet’s AC2 (GAC2). Thirty-eight raters scored histopathological DCIS features including grade (2-tiered and 3-tiered), growth pattern, mitotic activity, periductal fibrosis, and lymphocytic infiltrate in 342 women. Using majority opinion-based scores for each feature, their association with subsequent iIBC risk was assessed using Cox regression. Results Interrater reliability of grade using various classifications was fair to moderate, and only substantial for grade 1 versus 2 + 3 when using GAC2 (0.78). Reliability for growth pattern (KA 0.44, GAC2 0.78), calcifications (KA 0.49, GAC2 0.70) and necrosis (KA 0.47, GAC2 0.70) was moderate using KA and substantial using GAC2; for (type of) periductal fibrosis and lymphocytic infiltrate fair to moderate estimates were found and for mitotic activity reliability was substantial using GAC2 (0.70). Only in patients treated with BCS-RT, high mitotic activity was associated with a higher iIBC risk in univariable analysis (Hazard Ratio (HR) 2.53, 95% Confidence Interval (95% CI) 1.05–6.11); grade 3 versus 1 + 2 (HR 2.64, 95% CI 1.35–5.14) and a cribriform/solid versus flat epithelial atypia/clinging/(micro)papillary growth pattern (HR 3.70, 95% CI 1.34–10.23) were independently associated with a higher iIBC risk. Conclusions Using majority opinion-based scores, DCIS grade, growth pattern, and mitotic activity are associated with iIBC risk in patients treated with BCS-RT, but interrater variability is substantial. Semi-quantitative grading, incorporating and separately evaluating nuclear pleomorphism, growth pattern, and mitotic activity, may improve the reliability and prognostic value of these features.

Follicular dendritic cell sarcoma (FDCS) is an intermediate-grade malignancy of follicular dendritic cells, which are derived from mesenchymal stem cells. Nodal FDCS is well-recognized. However, when it occurs at an extranodal site, it may not be recognized and is often misdiagnosed. These tumors exhibit a variable spindle to epithelioid cell morphology with a lymphocytic infiltrate and a distinct immunophenotype. The World Health Organization has classified this entity under tumors of hematopoietic and lymphoid tissue, that is, histiocytic and dendritic cell neoplasms. However, its occurrence at extranodal sites and its behavior and management more closely resemble that of a soft tissue tumor. Increased awareness about the existence of FDCS at extranodal sites may aid in the reduction of diagnostic errors. We wish to draw attention to this entity by reporting our experience of 54 cases of extranodal FDCS encountered over a period of 14 years and present a review of the literature of this underrecognized entity. We also describe the ontogeny and molecular pathogenesis of this uncommon lesion.

Within the literature, there is overlap in the histopathological features described in eosinophilic folliculitis associated with chronic lymphocytic leukemia (CLL), eosinophilic dermatosis of hematologic malignancy, and acneiform follicular mucinosis. These disorders are described with varying degrees of superficial and deep lymphocytic and eosinophilic inflammation demonstrating perivascular, perifollicular, and folliculocentric involvement with or without follicular mucin deposition. Given significant histopathological overlap, these diagnoses may represent a continuum on a spectrum of dermatoses. Here, we present two cases with histopathological elements that reflect components of this clinicopathological spectrum and compare our findings with previously reported cases to compare and contrast reported features. Our first case is a 71-year-old African American man with long-standing CLL who developed a pruritic erythematous papular eruption on the face and chest with biopsy revealing a dense folliculotropic lymphocytic infiltrate with conspicuous eosinophils and follicular mucinosis. Our second case is a 70-year-old Caucasian man recently diagnosed with CLL/small lymphocytic lymphoma who developed an erythematous papular rash on the neck and face with biopsy revealing superficial and deep perivascular and periadnexal lymphocytic inflammation with scattered eosinophils. Characterization of our two cases and comparison with available literature suggest that these disorders may represent a continuum of dermatoses.

Insulitis is a characteristic inflammatory lesion consisting of immune cell infiltrates around and within the pancreatic islets of patients with recent-onset type 1 diabetes (T1D). The infiltration is typically mild, both in terms of the number of infiltrating cells and the number of islets affected. Here, we present an unusual histopathological case study of a 66-year-old female patient with long-standing T1D, insulitis, and islet-associated lymphoid tissue. Most islets in the head of the pancreas of this patient were insulin-deficient, whereas the islets in the tail appeared normal. Insulitis was present in 0.84% of the insulin-containing islets and three islets had large lymphocytic infiltrates resembling tertiary lymphoid structures (TLS). Of note, this is the first description of potential TLS in the endocrine pancreas of a patient with T1D. Their association with a marked residual beta cell mass is of interest and may hint at new insights into disease progression and regulation of autoimmunity. Electronic supplementary material The online version of this article (10.1007/s00428-020-02915-4) contains supplementary material, which is available to authorized users.

Case Presentation A woman in her late 40s with a history of recurrent deep vein thromboses and hypersensitivity pneumonitis (HP) presented to the ED with progressive exertional dyspnea and productive cough. She recently had started oral corticosteroids after HP was confirmed via transbronchial lung cryobiopsy from both the right upper and lower lobes, which showed poorly formed granulomas with mild interstitial and perivascular lymphocytic infiltrates. A causative antigen for her HP was never clearly identified.

Here, we report the pathological findings of nine complete autopsies of individuals who died in community settings in the UK, three of which were positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), three tested negative for SARS-CoV-2 but are likely false negatives, and three died of other respiratory infections. Autopsy revealed firm, consolidated lungs or lobar pneumonia. Histology of the lungs showed changes of diffuse alveolar damage with fibrin membrane formation, thickened alveolar walls and interstitium with lymphocytic infiltrate, and type 2 pneumocyte hyperplasia with shedding into the alveolar space. This series is the first in the world to describe autopsy findings in individuals dying suddenly in the community, not previously known to have COVID-19 infection, and the first autopsy series in the UK. During a time when testing in the UK is currently primarily offered to patients in hospital or symptomatic key workers, with limited testing available in community settings, it highlights the importance of testing for COVID-19 at autopsy. Two deaths occurred in care homes where a diagnosis of COVID-19 allowed the health protection team to provide support in that ‘closed setting’ to reduce the risks of onward transmission. This work highlights the need for frequent COVID-19 testing in the management of patients in community settings. Comprehensive virology and microbiology assessment is pivotal to correctly identify the cause of death, including those due to COVID-19 infection, and to derive accurate death statistics.

Context The relationship between the endocrine system and autoimmunity has been recognized for a long time and one of the best examples of autoimmune endocrine disease is autoimmune hypophysitis. A better understanding of autoimmune mechanisms and radiological, biochemical, and immunological developments has given rise to the definition of new autoimmune disorders including autoimmunity-related hypothalamic–pituitary disorders. However, whether hypothalamitis may occur as a distinct entity is still a matter of debate. Evidence Acquisition Here we describe a 35-year-old woman with growing suprasellar mass, partial empty sella, central diabetes insipidus, hypopituitarism, and hyperprolactinemia. Evidence Synthesis Histopathologic examination of surgically removed suprasellar mass revealed lymphocytic infiltrate suggestive of an autoimmune disease with hypothalamic involvement. The presence of antihypothalamus antibodies to arginine vasopressin (AVP)-secreting cells (AVPcAb) at high titers and the absence of antipituitary antibodies suggested the diagnosis of isolated hypothalamitis. Some similar conditions have sometimes been reported in the literature but the simultaneous double finding of lymphocytic infiltrate and the presence of AVPcAb so far has never been reported. Conclusions We think that the hypothalamitis can be considered a new isolated autoimmune disease affecting the hypothalamus while the lymphocytic infundibuloneurohypophysitis can be a consequence of hypothalamitis with subsequent autoimmune involvement of the pituitary. To our knowledge this is the first observation of autoimmune hypothalamic involvement with central diabetes insipidus, partial empty sella, antihypothalamic antibodies and hypopituitarism.

Decorative tattooing is very popular worldwide and is associated with cutaneous complications, ranging from infections to localized or generalized skin reactions. We report a case of a patient presenting with generalized violaceous pruritic papular lesions 1 month after obtaining a black ink tattoo. Histological examination of a papular lesion distal to the tattoo site showed focal band-like lymphocytic infiltrate. He subsequently developed bullae over the papular lesions, with elevated serum BP180 antibody levels. A diagnosis of generalized lichen planus and lichen planus pemphigoides was made. He responded to treatment with potent topical corticosteroids and ciclosporin. We also reviewed the presentation and treatment of published cases of lichenoid reactions in the literature. With the increasing popularity of tattoos, awareness of this potential complication and possible treatments is important.

Intestinal inertia is a severe form of gut dysmotility that may require surgical resection. Loss of myenteric ganglion cells has been proposed as a possible etiology. Preclinical models have also suggested that virus infection-associated ganglionitis may be an alternative pathogenic factor. We determined to the extent intestinal inertia is associated with the lack of myenteric ganglion cells or ganglionitis using resection specimens from 27 intestinal inertia and 28 colon cancer patients. A hot spot approach with 5 HPFs was used for quantifying inflammatory cells. CD3, CD8, and CD20 immunohistochemistry was used to quantify T and B lymphocytes, along with subtyping the T-lymphocyte population by CD8. None of the intestinal inertia nor control cases showed the absence of myenteric ganglion cells. A total of 15 (55.6%) of the intestinal inertia cases showed inflammatory cell infiltration in the myenteric ganglion cells, compared with only 1 of 28 (3.6%) control cases (P

Objective The aim of the study was to describe the clinical and histopathologic features required for a clinicopathologic diagnosis of vulvar lichen planus (LP), which is divided into 3 types: erosive, classic, and hypertrophic. Materials and methods The International Society of the Study of Vulvovaginal Diseases tasked the Difficult Pathologic Diagnoses committee with development of a consensus document for the clinicopathologic diagnosis of vulvar LP, lichen sclerosus, and differentiated vulvar intraepithelial neoplasia. The LP subgroup reviewed the literature and formulated diagnostic criteria, then approved by the International Society of the Study of Vulvovaginal Diseases membership. Results The clinicopathologic diagnosis of erosive LP incorporates 5 criteria: (a) a well-demarcated, glazed red macule or patch at labia minora, vestibule, and/or vagina, (b) disease affects hairless skin, mucocutaneous junction, and/or nonkeratinized squamous epithelium, (c) evidence of basal layer damage, categorized as degenerative or regenerative, (d) a closely applied band-like lymphocytic infiltrate, and (e) absent subepithelial sclerosis. The clinicopathologic diagnoses of classic and hypertrophic LP each require a characteristic clinical appearance accompanied by hyperkeratosis, hypergranulosis, acanthosis, basal layer degeneration, a closely applied lymphocytic infiltrate, and absent dermal sclerosis, with hypertrophic LP showing marked epithelial abnormality compared with classic LP. Conclusions Clinicopathological correlation yields the most reliable diagnosis of vulvar LP. Disease appearance overlaps with other physiologic, dermatologic, infectious, and neoplastic entities; a low threshold for biopsy at all morphologically distinct areas is recommended. Use of the histopathologic criteria described in this document may reduce the nondiagnostic biopsy rate for clinically diagnosed LP.

Although emergence of keratin 17 (K17) and reciprocal loss of K13 are immunohistochemical hallmarks for oral mucosal malignancy, we report here findings of K17-positive (+) speckles, possibly equivalent to Civatte bodies, in benign oral lichen planus. Sixty-two biopsy samples from oral lichen planus cases were subjected to immunohistochemical examinations to analyze the distribution as well as histopathogenesis of Civatte bodies. K17 was irregularly positive among oral lichen planus-affected epithelial cells, and K17-positive (+) filamentous structures were irregularly distributed within the cytoplasm in confocal images. K17+ speckles were identified as Civatte bodies, and they were mainly distributed in the interface between epithelial cells and lymphocytic infiltrates (type A, 52.8%), followed by distribution within the epithelial layer (type B, 24.7%) or within the lamina propria with lymphocytic infiltration (type C, 22.5%). Apoptotic figures were often engulfed by macrophages and clearly distinguished from Civatte bodies by the presence TUNEL signals. These results indicate that K17 is a sensitive immunohistochemical marker for Civatte bodies and useful for differential diagnosis of oral lichen planus from other oral mucosal lesions. Civatte bodies are generated from denucleation of K17+ epithelial cells during the process of cell death via dyskeratosis, which is possibly related to blood capillary collapse.

Background Cellular dermatofibromas (CDFs) and dermatofibrosarcoma protuberans (DFSP) can be challenging to differentiate from one another. Morphologically, both entities commonly extend into the subcutis, exhibit high cellularity with limited cytologic atypia and have a mixed fascicular-to-storiform growth pattern. We sought to evaluate the significance of fat necrosis with an associated lymphocytic infiltrate as a histopathologic clue for distinguishing CDFs from DFSP. Methods We identified cases in our pathology database with a primary diagnosis of CDF or DFSP. Punch or excisional biopsy specimens with extension into the subcutis were selected. Previously biopsied lesions and specimens that did not interact with the subcutis were excluded. Histopathologic features were evaluated in hematoxylin and eosin stained sections. Results Fat necrosis with lymphocytic infiltrate was present in 20/20 cases of CDF. None of the 20 DFSP cases had fat necrosis with lymphocytic infiltrate although 4/20 had fat necrosis alone. Conclusions Fat necrosis with associated lymphocytic response can aid in the distinction between CDF and DFSP.

The histology of erythema (chronicum) migrans (ECM) is classically described as a nonspecific perivascular infiltrate with a variable number of plasma cells and eosinophils. However, deviations from this pattern were described, such as focal interface changes or spongiosis, potentially posing a clinicopathological challenge. In this study, cases submitted with a serologically confirmed, clinically unequivocal, or highly suspicious diagnosis of ECM/Lyme disease between January 01, 2016, and September 01, 2018, were retrieved from the electronic database system and reviewed to delineate the histopathologic features of ECM. The series consisted of 14 cases. A superficial perivascular lymphocytic infiltrate was noted in all biopsies, accompanied by a deep and/or interstitial inflammatory infiltrate in 9 cases (64%). The inflammation ranged from relatively sparse to dense and prominent. At least focal interface changes were noted in 12 biopsies (86%). Eosinophils and plasma cells were noted in 7 (50%) and 10 (71%) cases, respectively. From a histologic standpoint, ECM is a protean entity and may manifest with a variable density of perivascular and/or interstitial lymphocytic infiltrate admixed with eosinophils and/or plasma cells and accompanied by focal interface dermatitis. Within the appropriate clinical context, ECM should be considered in the differential diagnosis of focal interface and/or sparse perivascular dermatitis.

In melanoma, the lymphocytic infiltrate is a prognostic parameter classified morphologically in “brisk”, “non-brisk” and “absent”. The meaning of “brisk” is “active, energetic”, implying a functional connotation which has never been proved. Recently, it has been shown that not all brisk infiltrates have a good prognosis, that lymphocytic populations can be very heterogeneous, and that anti-PD-1 immunotherapy supports activated T cells. Here, we characterize the immune landscape in primary melanoma by high-dimensional single cell multiplex analysis in tissue sections (MILAN technique) followed by image analysis, RT-PCR and shotgun proteomics. We observed that the brisk and non-brisk patterns of tumor infiltrating lymphocytes (TILs) in primary melanoma are heterogeneous functional categories that can be further sub-classified according to the functional status of their lymphocytes as active, transitional or exhausted. We found that only activation of TILs correlates with spontaneous regression, and that the good prognosis of melanomas with a brisk pattern could be due to the fact that in these case the Tcy that are in contact with the melanoma cells are still active, and consequently the melanoma is still under immune control at the moment of surgical excision. The main inflammatory cell subpopulations that are present in the microenvironment associated with activation and exhaustion and their spatial relationships are described using neighbourhood analysis. Finally, we show a bioinformatic pipeline that, starting from common immunofluorescence stainings, can transform the tissue into a digitalized image, which represents the starting point for multiple deeper levels of analysis.