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Sarcomatous serous effusions are uncommon and diagnostically challenging. Dedifferentiated and pleomorphic liposarcomas are rare tumors in pleural effusions revealing highly pleomorphic tumor cells mimicking carcinoma, mesothelioma, melanoma, and other sarcomas. Hematothoracic effusions further complicate the cytologic diagnosis. Correct cytologic recognition is important. We report pleomorphic liposarcoma cytologically detected in effusion fluid in a 56-year-old man who presented with a massive unilateral pleural effusion. ThinPrep showed hemorrhagic effusion fluid characterized by lysed red blood cells, foamy macrophages, and siderophages intermixed with highly pleomorphic predominantly naked mononuclear and giant nuclei. The aggregated siderophages and vacuolated macrophages could be mistaken for tumor cells, whereas the bare nuclei may be missed as nonspecific degenerate changes. Cellblock sections showed highly pleomorphic mononuclear and multinucleated giant tumor cells with diagnostic lipoblasts, intermixed with foamy macrophages and siderophages. Cellblock immunocytochemistry showed staining for vimentin and S-100 protein in the tumor cells. Other lineage-specific immunomarkers were negative. CD68 and calretinin revealed frequent background macrophages and scarce mesothelial cells. The tumor cells were negative for MDM2 and CDK4. The entertained cytopathologic diagnosis was pleomorphic liposarcoma. Core needle biopsy was procured from the mass. The histopathologic features and immunoprofile of the tissue specimen matched the cytopathologic and immunocytochemical findings confirming the cytologic diagnosis of pleomorphic liposarcoma. Pleomorphic liposarcoma is an unexpected cytologically challenging finding in effusions, particularly when compounded by pitfalls introduced by hemosiderotic fluid. Attention to certain cytologic clues mitigate pitfalls. Cellblock is a valuable diagnostic tool when integrated with relevant negative and positive immunocytochemical markers., (© 2024 Wiley Periodicals LLC.)

Pap smears play a role in detecting extrauterine serous tumours in asymptomatic women. Certain cytopathologic and histopathologic findings combined with relevant clinical and radiologic findings indicate the possibility of primary peritoneal serous tumours. Cellblock immunohistochemistry is a valuable confirmatory diagnostic tool., (© 2024 John Wiley & Sons Ltd.)

Synovial lipomatosis is a controversial entity of uncommon intraarticular joint lesions. Most studies focused on radiological findings and surgical resection modalities. Pathologic findings were limited to case reports. Detailed descriptions of the histopathologic features are lacking. We aim to highlight the salient histopathologic features of synovial lipomatosis. We performed a retrospective review study over 15 years retrieving cases of synovial lipomatosis. We found 5 patients (age range: 8-78, average age: 50 years, male to female ratio: 4:1) demonstrating unilateral synovial lipomatosis out of 241 (2.0%) patients with knee joint lesions. Four patients had osteoarthritis. One patient was obese. The resected specimens showed synovial hyperplasia, surface fibrin, hemosiderin pigment, microcalcifications, lymphoplasmacytic infiltrates, lymphoid aggregates, stromal fibrotic, degenerative, and metaplastic alterations shared by other synovitis related changes. Consistent features included abundant adipocytic components, surface adipocytes, prominent large vessel vasculatures, plasma cells, and dense perivascular lymphocytic cuff-like infiltrates. One patient demonstrated superimposed sarcoid-type epithelioid granulomas. A distinct fibrous band separated the lesional tissue from the underlying normal fatty tissue. Synovial lipomatosis predominates in older males with degenerative joint conditions with a second peak in children and adolescents. Obesity is not a risk factor. Some histopathologic features help distinguish synovial lipomatosis from look-alike joint lesions. The findings may suggest an angiolipomatous hamartomatous growth or an exaggerated synovial reaction inducing florid subsynovial stromal proliferative, metaplastic, and degenerative changes. Regardless of its etiopathogenesis, pathologists have a role in confirming the diagnosis and ensuring a complete arthroscopic synovectomy by assessing the presence of the fibrous septa., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Abstract: Rhabdomyomatous mesenchymal hamartoma (RMH) typically presents as a congenital midline head and neck cutaneous polyp in infants. Perianal and mucocutaneous lesions have been reported, and recently, acquired adult-onset variants have been proposed. This makes the true prevalence, etiopathogenesis, and clinicopathologic distribution and classification of RMHs in children compared with those in adults uncertain. We performed a retrospective review to highlight the salient histopathologic, histochemical, and immunohistochemical features in RMHs and to emphasize their specific clinicopathologic criteria to avoid diagnostic pitfalls. We found 4 (0.3%) infants [2 female infants and 2 male infants, average age: 4 months] with mental, nasal, lingual, and perianal midline RMHs (average size: 1.0 cm) of 1303 patients with cutaneous polypoid lesions. Three were isolated, and 1 was associated with Goldenhar syndrome. The cutaneous polyps demonstrated intermixed skeletal muscle, adipose, and fibrocollagenous core stroma that extended into the dermis and around the dermal appendages. The lingual lesion demonstrated skeletal muscle and fibrocollagenous stroma with prominent nerve bundles and little adipose tissue. All showed interstitial loose mesenchyme. Masson trichome demarcated the triphasic stromal components. Alcian blue demonstrated the loose myxoid mesenchyme. Elastic van Gieson did not show elastic fibers. Desmin demonstrated the skeletal muscle bundles, S100 highlighted the adipose tissue lobules and the nerve bundles, and CD34 displayed the mesenchymal stroma. Ki67 showed a low proliferation index in the loose mesenchyme. Smooth muscle actin did not reveal smooth muscle bundles, but with CD31, they highlighted the thick blood vessels. CD117 revealed prominent mast cells. From our retrospective review series, 4 cases that originally diagnosed as RMHs were excluded. Likewise, we found some examples of the reported cases in the English literature that might have been mistaken for RMHs. This is because they did not fulfill the diagnostic clinicopathologic criteria. RMH constitutes a rare entity with specific clinicopathologic features. Most lesions are isolated. Some are associated with congenital anomalies and syndromes. Strict clinicopathologic diagnostic criteria should be applied to avoid mislabeling look-alike lesions for RMHs., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Comorbidities between tuberculosis and leprosy are expected in endemic regions. Pulmonary tuberculosis and cutaneous leprosy are the most prevalent coinfections. One of the common manifestations of tuberculosis is generalized lymphadenopathy. In contrast, leprosy is clinically less suspected to manifest as a generalized lymphadenopathy, and it is pathologically unusual to diagnose leprosy primarily in lymph nodes. Concomitant tuberculous and lepromatous lymphadenitis are unprecedented and clinically unexpected, particularly in nonendemic countries. This imposes diagnostic challenges. We report concurrent tuberculosis and leprosy that were diagnosed in a lymph node in 45-year-old man with generalized lymphadenopathy. The effaced lymph node was predominantly replaced by caseating epithelioid granulomas alternating with foamy histiocytes. Ziehl-Neelsen stain showed positive acid-fast bacilli in the necrotizing granulomas only. The initial differential diagnosis of the nodal foamy macrophages included fungal infections, leishmaniasis, and Whipple disease, for which the special stains were negative. The vacuolated macrophages were disregarded as nonspecific lipogranuloma. A modified acid-fast stain was not considered. The histopathologic clues to nodal lepromatous leprosy included the presence of intracytoplasmic globi, intermixed microabscesses, and lymphoplasmacytic infiltrate and involved pericapsular nerves. Wade-Fite stain was subsequently performed. It revealed numerous lepra bacilli within the foamy histiocytes. The final diagnosis was concurrent disseminated tuberculosis and leprosy. Nodal lepromatous leprosy could be missed when compounded by concurrent nodal tuberculosis, particularly in developed countries. The clinicians and pathologists should have a high index of suspicion, particularly in patients from or with history of travel from endemic regions. Certain histopathologic features are helpful clues to avoid pitfalls., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Zygomycotic fungal infections are increasingly recognized in immunocompetent and immunocompromised patients in nonendemic countries because of the increased global travels. One of the emerging fungal infections is Entomophthorales which cause deep visceral infections that clinically and radiologically mimic malignancies because they form invasive obstructing masses. A quick diagnosis is life-saving. The current standard diagnosis relies on histopathologic examination and microbiology culture which are time consuming. Cytologic examination is a rapid reliable alternative diagnostic tool. There are a few reports of a primary cytologic diagnosis of zygomycotic and Aspergillus fungi of the lungs based on conventional smear and SurePath™ liquid-based cytology. We report a case of an immunocompetent adult female who presented with a liver mass that was clinically and radiologically diagnosed as cholangiocarcinoma. Fine-needle aspiration cytology revealed the cytopathologic features of basidiobolomycosis in ThinPrep® cytology. The ThinPrep® slide revealed broad thin-walled widely branching septate hyphae with sporangiophores and zygospores. The background revealed bile-stained granular necrotic debris intermixed with inflammatory cells, degenerate hepatocytes, and highly eosinophilic glassy crystal-like structures suggestive of Splendore-Hoeppli phenomenon. The cytologic diagnosis was hepatic entomophthoromycosis (basidiobolomycosis) with Splendore-Hoeppli phenomenon. This was confirmed by subsequent tissue biopsy and microbiology culture. The detailed cytomorphologic features in the ThinPrep® slide allowed the correct cytologic diagnosis and proper classification of the filamentous fungi. The ThinPrep® cytology was superior to tissue biopsy because it was faster and revealed the characteristic pauciseptate fungal hyphae, sporangiophores and zygospores. Liquid-based cytology is a valuable quick tool in the diagnosis of fungal mass-forming lesions., (© 2023 Wiley Periodicals LLC.)

Competing Interests: The authors declare no conflicts of interest.

Extranodal follicular dendritic cell sarcomas are infrequent diagnostically challenging tumors. Because of their rarity, heterogeneous histomorphologic features and variable histologic grades a significant number of extranodal lesions are prone to be misdiagnosed. Even though they have a characteristic immunoprofile, expression of a range of nonspecific markers is well documented. Even though they are typically negative for keratins, few authors have reported lesions expressing keratin. Keratin expressing tumors are more likely to be misinterpreted by pathologists further deterring their inclusion in the differential diagnosis. We report an intraabdominal mesenteric follicular dendritic cell sarcoma in a 44-year-old male that immunophenotypically expressed keratin antigens. The lesion showed a high-grade pleomorphic epithelioid appearance and the initial differential diagnosis included lymphoma, sarcomas, melanoma, and carcinomas. Follicular dendritic cell sarcoma was not considered. Expression of epithelial membrane antigen and keratin further deterred the diagnosis which was reached only after extensive use of immunomarkers. The tumor cells expressed CD21, CD23, and D2-40. Morphologically, the tumor showed some thymoma-like features with occasional TDT-expressing background T-lymphocytes. These features were hints to reconsider our differential diagnosis to include follicular dendritic cell tumors. Awareness of this aberrant staining of epithelial immunomarkers and attention to certain clues should encourage pathologists to consider this entity. Speculative assumptions may explain this unusual keratin expression in some lesions. The histomorphologic and immunohistochemical heterogeneity may suggest different variants and grades of follicular dendritic cell sarcomas. The prevalence, importance, and histogenesis of keratin expression in follicular dendritic cell sarcomas warrant further studies., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Similar to celiac disease, inflammatory bowel disease frequently manifests in the duodenum. Histopathologic studies focused on mucosal alterations with little attention to submucosal Brunner glands. Recently, several studies have demonstrated overlapping features between Crohn's disease and celiac disease suggesting a putative link. However, histopathologic studies evaluating this possible link are limited, and those that are focused on Brunner glands are lacking. The present study aims to explore whether Crohn's disease and celiac disease display shared or overlapping inflammatory changes in Brunner glands. We performed a retrospective review study over 17-years retrieving duodenal biopsy specimens containing Brunner gland lobules in patients with Crohn's disease, celiac disease, and ulcerative colitis. We found 10 out of 126 duodenal biopsies (8 %) in patients with Crohn's disease and 6 out of 134 (4.5 %) duodenal biopsies in patients with celiac disease sharing inflammatory patterns in duodenal Brunner gland lobules. Both diseases showed interstitial intralobular and interlobular mixed chronic inflammation with variable fibrosis. Focally enhanced active inflammation of Brunner gland lobules was more characteristic of Crohn's disease. Intralobular epithelioid granulomas and multinucleated giant cells were specific to Crohn's disease. Ulcerative colitis patients did not show similar features. The interstitial focally enhanced chronic inflammatory pattern was significantly (p < 0.05) associated with both diseases, while the other inflammatory patterns were not (p > 0.05). This overlapping inflammatory pattern in Brunner glands in patients with Crohn's disease and celiac disease is supportive of the previously reported link between the two diseases. Pathologists should pay more attention to Brunner glands when evaluating duodenal biopsies. Further studies are warranted to validate these observations and their relevance in the pathogenesis of autoinflammatory gastrointestinal diseases., Competing Interests: Declaration of competing interest No conflict of interests or financial disclosure to be declared by the authors., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Foreign bodies in the maxillary sinus are infrequent findings with various organic and inorganic materials have been reported. Most are iatrogenic due to abnormal communications between the oral cavity and the sinus cavity, predominantly secondary to dental and oral procedures. Oroantral fistulas might be asymptomatic incidental findings or may present with sinusitis-related symptoms. Even though oroantral fistulas are frequently encountered iatrogenic complications, most studies focused on radiologic findings and surgical closure procedures. A few cases reported the histopathologic findings of foreign body-related antral sinusitis. Our aim is to report three cases of chronic maxillary sinusitis induced by various foreign bodies of oral and dental origin associated with oroantral fistulas. Our focus is to highlight the different histopathologic patterns, potential pitfalls and helpful clues of foreign body-induced maxillary sinusitis. Altered foreign bodies in procured sinus specimens might be missed, misinterpreted or ignored by pathologists. Obvious vegetable food remnants were detected, but subtle vegetable residuals showed pulse granuloma, rings and sheet-like patterns embedded in the granulation tissue and fibrous stroma. Some materials mimicked fungal hyphae while others were ignored as nonspecific debris. Periodic acid Schiff stain and polarizing light helped delineate their nature. Other helpful hints included the presence of oral-type squamous epithelium, crystals, hemosiderin pigments, dental materials such as alvogyl, and microorganisms of oral origin for example Actinomyces. Our series emphasizes the importance of correct recognition of foreign bodies of oral and dental origin in paranasal specimens to guide clinicians to the possibility of oroantral fistula-associated odontogenic sinusitis versus conventional rhinosinusitis.

Background: A button battery can cause perforation of Meckel's diverticulum if sequestered in this blind ending bowel segment. Reported cases focused on clinical manifestations, management options, radiologic and intraoperative findings. We highlight the histopathologic features in perforated Meckel's diverticula due to ingested button batteries. Case report: Three toddlers presented with perforated Meckel's diverticula after button battery ingestion. Histologic examination of the diverticula showed multiple burn-like mucosal ulcerations and liquefactive wall perforations of the tips, associated with prominent siderotic pigment deposits and calcifications. There were various residual materials with variable staining patterns in the luminal debris, necrotic tissue and adjacent to submucosal blood vessels. Conclusion: There is accelerated deposition of iron and calcium associated with button batteries.

Acute myeloid leukemic pleural effusions are uncommon with heterogenous cytomorphology and variable immunoprofiles. This imposes a difficult cytologic diagnosis. In particular, acute myeloid leukemia of monocyte lineage mimicking benign and malignant lymphoid and non-lymphoid lesions is challenging. Few cases of acute myeloid monocyte-lineage leukemia have been reported. Our aim is to report a case of a 54-year-old female patient who presented with pancytopenia and bilateral pleural effusions. We highlight the characteristic cytomorphologic features, diagnostic pitfalls and helpful hints of acute monoblastic leukemia. Initially, the cells were misinterpreted as chronic inflammatory histiocytic infiltrates with reactive mesothelial cells. The presence of frequent mitotic figures, apoptotic bodies and a two-cell population raised the possibility of neoplastic cells. The cellular infiltrate simulated lymphoma, carcinoma and melanoma tumor cells. Cellblock immunocytochemistry however showed negative B-cell, T-cell, myeloid, Langerhans cell, plasma cell and dendritic cell lineage markers. They were positive for LCA, CD68, CD4 and CD117 with a high Ki67 index. The cytologically suggested impression of acute myeloid leukemia of monocyte origin favoring monoblastic variant was confirmed by flow cytometry and bone marrow trephine biopsy. Cytomorphologic clues included agranular amphophilic cytoplasm, occasional grooved indented nuclei, tingible body macrophages, associated plasma cells and absent granulocytes. The cytologic and cellblock findings matched the bone marrow trephine biopsy features. Cytopathologists should be aware of this unusual and challenging cytologic diagnosis in patients with pancytopenia and utilize at least two monocyte markers when formulating their differential diagnosis. Certain cytomorphologic features are helpful hints for their correct recognition., (© 2022 Wiley Periodicals LLC.)

Competing Interests: The authors have no funding or conflicts of interest to disclose.

Necrotizing and non-necrotizing epithelioid granulomatous chronic inflammation is the usual recognizable histopathologic presentation of mycobacterial infections. In immunosuppressed patients, atypical histomorphologic patterns may occur. Rare and diagnostically challenging manifestations of nontubercular mycobacterial infections in transplant and Human Immunodeficiency Virus (HIV)-infected patients include mycobacterial spindle cell pseudotumor and suppurative lesions. Lesions composed of nodular spindle cell proliferation mimicking inflammatory, histiocytoid and spindle cell tumors, and similarly suppurative lesions simulating abscesses have been mostly reported in association with nontuberculous mycobacterial infections mainly in nodal and various extranodal sites. Similar lesions related to Mycobacterium tuberculosis that involve serosal membranes are unusual and diagnostically challenging. Our aim is to report mycobacterial spindle cell pseudotumor-associated pericarditis, suppurative abscess-forming pleuritis, and cholesterol pleuritis due to tuberculosis in three HIV-infected young adult males. Initially, we confused the mycobacterial spindle cell pseudotumor for Kaposi sarcoma, the suppurative pleuritis for bacterial and fungal empyema, and the cholesterol pleuritis with rheumatoid arthritis. A prior knowledge of the immune status of our patients helped us confirm our final correct diagnosis of mycobacterial infection by performing Ziehl-Neelsen special stain. Polymerase chain reaction detected Mycobacterium tuberculosis in respiratory samples. Utilization of acid-fast special stains in all HIV-patients regardless of the histopathologic appearances, and the application of an appropriate panel of immunomarkers should help pathologists reach the correct diagnosis and avoid pitfalls. Without prior clinical knowledge, pathologists should raise this possibility in young patients with such unusual manifestations, because correct pathologic recognition is clinically important for the appropriate management of these vulnerable patients.

Serous effusions occur in a small group of patients with classic Hodgkin lymphoma (cHL). Most effusions are benign inflammatory fluids. Malignant effusions predominantly in patients with treated relapsed diseases or rarely as a primary manifestation are diagnostically challenging to cytopathologists. Established cases of cHL with effusions were retrieved. Cytology slides were screened looking for Reed-Sternberg-Hodgkin (RSH) cells and patterns of background inflammatory cells. Cellblocks and their corresponding immunocytochemistry (ICC) slides were examined. The cytologic findings were correlated with nodal biopsy histopathologic and immunohistochemical features. We found six cases of benign and malignant pleural and pericardial effusions in patients with mediastinal nodular sclerosis-type cHL. Various cytomorphologic patterns were observed. Slides revealed sparsely scattered either isolated or aggregated mononuclear, binucleated and multinucleated RSH-like cells. Some may have been either disregarded as reactive mesothelial or histiocytic cells, or confused with other RSH-like malignant cells. The background varied between characteristic mixed inflammatory milieu, predominantly small lymphocytic or lymphohistiocytic with or without reactive mesothelial cells. Cytologic examination showed three positive cases (two cases with RSH cells confirmed by cellblock section ICC, one case with a mixed inflammatory infiltrate), and three benign effusions (one case with atypical RSH-like reactive mesothelial cells confirmed by ICC). Effusions associated with cHL exhibit different cytologic patterns. A high level of vigilance with utility of ICC has an important role in suspecting primary cases and confirming recurrences in known cases. The various cytologic patterns of cHL-associated benign and malignant effusions might reflect parallel pathophysiologic mechanisms., (© 2022 Wiley Periodicals LLC.)

As one of the emerging complications of caesarean sections (CSs), pathologists will have an important role in handling samples of uterine niches. An isthmocele is a defect at the site of a previous CS scar resulting in a variety of symptoms and niche-related subfertility. There is a deficiency in the literature of the histopathologic features of hysteroscopy-resected isthmocele ridges. Our aim is to fill this gap to highlight what to expect to see and what important findings to report to guide gynecologists to the results of hysteroscopic isthmoplasty in relation to symptoms improvement, fertility restoration, and potential complications. We found 22 cases of hysteroscopy-resected isthmoceles by performing a retrospective review study. The majority of the women were symptomatic with secondary infertility. The resected isthmocele edges were lined by endocervical, endometrial, and isthmic mucosa either combined or isolated depending on each case. Isthmoceles could be classified depending on the predominant lining mucosa into endocervical-isthmoendocervical (low) and endometrial-isthmic (high-intermediate) niches. This could be correlated with certain symptoms. The edges showed variably thickened fibrous and fibromuscular stromal tissue with characteristic thick-walled blood vessels. Some cases showed miscellaneous findings such as hemosiderin pigments with foreign body giant cell reaction and placental implantation site tissue reflecting a previous history of surgical repair and scar pregnancy. Cauterization artifacts may impose interpretation challenges for pathologists. Utility of certain special stains helps delineate the nature of badly cauterized tissues. It is important to report certain histologic findings in isthmocele samples to correlate with clinical findings and guide gynecologists.

Quantum mechanics (QM) and surgical pathology might seem totally unrelated fields of science. Because QM or particle physics explains the very basic structure and function of nature, there are growing interconnections between the fundamentals and applications of QM and biologic sciences. QM is not only applied to the structure of atoms but also probes the structure of biologic molecules, explains their mutational changes and has provided an insight into the basic mechanisms of many different biologic systems. Many of the current applications in biologic sciences, medicine, and surgical pathology rely on the principles of QM. Because surgical pathology uses quantum phenomena such as light and studies disease's alterations that are ultimately governed by quantum changes at nanoscale levels, QM will have potential future implications for the progress of surgical pathology. These might include quantum-enhanced refinements in light, ancillary tools, and interpretation assistance computerized systems. The future of applying the concepts, discoveries, and tools of QM in surgical pathology might create something analogous to quantum biology; that is, quantum pathology or "QuPath.", Competing Interests: The author has no funding or conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Crohn disease (CD) not uncommonly involves the upper gastrointestinal tract, usually gastric antrum and proximal duodenum. The most consistent histopathologic manifestations of CD in duodenal biopsies are mucosal erosion, focal active inflammation, and granulomas. Since CD is a transmural inflammation and since duodenal biopsy may include submucosal Brunner glands, we aimed to find if CD has any specific histopathologic manifestations in Brunner gland lobules and their ducts compared to other duodenal inflammatory lesions. We carried out a retrospective review study over 6 years retrieving duodenal biopsy specimens in CD patients. We compared duodenal specimens involved by CD with other inflammatory lesions, for example, ulcerative colitis (UC), Helicobacter pylori -associated gastritis, non-Helicobacter gastritis, Celiac sprue, infections, and drugs. We found focal active duodenitis and erosion in CD cases and non-CD cases. Granulomas were found in CD cases. Five cases of CD showed inflammatory and degenerative changes of Brunner glands. Focal patchy active inflammation of only portion of submucosal Brunner gland lobule, mucosal Brunner glands, and their ducts was solely found in CD cases. This focally enhanced inflammation of Brunner glands was not found in other lesions. Whether this phenomenon of focal active "lobulitis" and "ductitis" is a specific sign of duodenal CD compared to UC and other inflammatory lesions warrants verification. We encourage endoscopists to include submucosal Brunner lobules in their duodenal biopsy samples and pathologists to look for these patterns of involvement particularly in patients suspected of CD.

Adult T-cell leukemia/lymphoma (ATLL) is a lymphoproliferative disorder of mature CD4-positive T-cell lymphoid cells associated with retrovirus human T-lymphotropic virus type-1 (HTLV-1) with a wide clinical and pathologic spectrum. We report a case of a 53-year-old African man who presented with fever and skin eruptions on the trunk composed of non-itchy erythematous reticulated macules and papules initially suspected for viral exanthem or drug rash. Skin punch biopsy showed a dermal T-cell lymphoid infiltrate with epidermotropism. The patient developed generalized lymphadenopathy and his peripheral blood showed lymphocytosis with atypical lymphocytes with convoluted nuclei. Our initial diagnosis was mycosis fungoides with Sézary syndrome. However, some clinical and histopathologic features were unusual. The acute onset, lack of previous skin lesions, the histomorphologic features of the dermal, nodal and peripheral blood lymphocytes and the geographic origin of the patient raised the suspicion of other T-cell lymphomas, particularly ATLL. This was confirmed by a positive anti-HTLV-1 serology. Our final diagnosis was acute variant ATLL. Different T-cell lymphomas can involve the skin with overlapping clinical, histomorphologic and immunohistochemical features. Some clinical and pathologic features should alarm dermatologists and pathologists to the possibility of ATLL particularly in patients from HTLV-1 endemic geographic areas., (© 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Diffuse large B-cell lymphoma (DLBCL) has some rare special subtypes. Anaplastic variant has the immunophenotypic and genotypic features of DLBCL, and is characterized by the presence of large bizarre hallmark-like and Reed-Sternberg-Hodgkin-like cells. Lymphoblastic lymphoma and DLBCL, non-otherwise specified are the most common lymphoma effusions in adults. Lymphomas in effusion fluids usually show a homogenous uniform population of either small, medium or large cells depending on lymphoma types. Anaplastic pleomorphic lymphoid cells in pleural effusions are not common cytologic findings. Effusions due to lymphomas with large bizarre anaplastic cells, such as anaplastic large cell lymphoma and Hodgkin lymphomas, are rare. Presence of anaplastic cells in effusion fluid is diagnostically challenging. They may be confused with nonlymphoid malignancies. Certain cytomorphologic features are helpful clues. Ancillary immunocytochemistry is a useful confirmatory tool in doubtful cases. We report two cases of anaplastic variant-DLBCL (ADLBCL) cytologically diagnosed in elderly female patients with bilateral pleural effusions. Cytologic examination of effusion fluids showed predominantly medium-large mononuclear uniform cells intermixed with frequent large pleomorphic mononuclear and binucleated cells, and bizarre multinucleated giant cells. Background showed karyorrhexis and absent mixed inflammatory infiltrates. A panel of immunocytochemistry markers in cell block sections confirmed B-cell phenotype of the neoplastic and anaplastic cells. Lymph node biopsy supplemented with immunohistochemistry confirmed the cytologic diagnosis. Even though the presence of anaplastic cells may be confused with other malignancies, cytopathologists should consider ADLBCL in the differential diagnosis of lymphomas with large pleomorphic cells, look for certain cytomorphologic clues and implement an appropriate immunocytochemistry panel., (© 2021 Wiley Periodicals LLC.)

Plasma cells are usually absent in normal bronchoalveolar lavage (BAL) fluids. Frequent plasma cells in BAL are always pathologically significant. They raise a rather narrow differential diagnosis, predominantly extrinsic allergic alveolitis and few other interstitial lung diseases. BAL is a key diagnostic procedure for certain lung diseases. Because plasma cells are uncommon in BAL fluids and usually associated with limited conditions compared to other more common interstitial lung diseases, the focus of cell count differentials in BAL fluids was on other mononuclear and granulocytic inflammatory cells. Recently, cases of IgG4 positive plasma cell-related lung diseases have been reported in tissue specimens. This may raise the importance of cytologically recognizing plasma cells in BAL fluids. We report a case of a 16-year-old boy with clinical and radiologic features of diffuse interstitial lung disease. His BAL cytology showed frequent plasma cells. Endobronchial biopsy showed substantial infiltration by plasma cells confirmed by immunohistochemistry. After excluding other lung diseases, the possibility of IgG4 plasma cell-related disease was raised. Blood tests showed elevated serum levels of IgG4. This case emphasizes the importance of including of IgG4 plasma cell-related lung disease as a possible differential diagnosis. This should prompt proper serologic tests for confirmation and appropriate management. With increasing reports of IgG4-related lung disease, cytopathologists should be aware of this possibility when examining BAL fluids. Measurement of IgG levels in BAL fluids and plasma cell immunophenotyping might be promising tools., (© 2021 Wiley Periodicals LLC.)

Competing Interests: Declaration of Competing Interest No conflict of interests to be disclaimed or financial disclosure to be declared.

Background: Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is the diagnostic tool of choice for pancreatic solid mass lesions. Pancreatic lymphomas represent an infrequent and challenging cytologic diagnosis. Our aim was to determine the diagnostic value of cellblock (CB) in the diagnosis of pancreatic lymphomas., Methods: We retrieved pancreatic EUS-FNAs performed over 10-years from our institution's database. We correlated the cytologic and CB diagnosis with the histologic diagnosis as a gold standard., Results: We found 5 cases (2 women and 3 men; age range, 37-66 years [average age, 52 years]) of pancreatic lymphomas with histologic follow-up biopsies. They included 1 case of T-cell lymphoma (TCL), 1 case of plasma cell neoplasm (multiple myeloma [MM]), 1 case of diffuse large B-cell lymphoma (DLBCL), 1 case of classic Hodgkin lymphoma (HL), and 1 case of high-grade B-cell lymphoma (HGBCL). Cytologically, the cases of HL and DLBCL were suspected, the cases of TCL and MM were confused with undifferentiated carcinoma and neuroendocrine carcinoma, and the case of HGBCL was inconclusive. CB samples were of value in highlighting the morphologic details of lymphomas and allowed confirmation, proper classification, and grading of the lymphomas using immunohistochemistry that matched tissue biopsies., Conclusions: EUS-FNA smears with CBs are helpful diagnostic tools, differentiating lymphomas from other malignancies and from nonneoplastic lymphocyte-rich lesions. CBs allow proper classification and grading of cases of pancreatic lymphomas., (© 2020 S. Karger AG, Basel.)

Pleural effusions can be the first manifestation, recurrence, or metastasis of small round cell sarcomas in children. The most common are Ewing sarcoma, neuroblastoma, and rhabdomyosarcoma. The cytomorphology is variable, the cells can be cohesive, single cells, small or large, morphologically mimicking lymphomas, carcinomas, melanomas, and mesothelioma depending on the sarcoma involved. Osteosarcomas are rare. Their rarity, variable histomorphologic features, immunophenotypic heterogeneity, being of osseous or extraosseous origin and focality of malignant osteoid matrix make their cytologic recognition a diagnostic challenge. They can be confused with small round cell sarcomas, may be misinterpreted as degenerative inflammatory cells, or masked by florid reactive mesothelial hyperplasia particularly in pleural effusions. However, attention to certain cytomorphologic features in smears and cellblock sections should raise suspicion. We report a case of a 9-year-old child who presented with cough, chest pain and breathing difficulty, left pleural effusion, a collapsed consolidated lower lung lobe, and a clinical impression of pneumonia. Pleural fluid cytology was initially reported as inflammatory effusion with florid reactive mesothelial hyperplasia. Tissue biopsy of the lung mass showed histomorphologic features consistent with osteosarcoma. A careful look at the cytology materials and cellblock sections showed helpful cytomorphologic features that were masked by florid reactive mesothelial cells and misinterpreted as degenerative inflammatory lymphocytes. An extracellular matrix was a helpful hint. Malignant pleural effusion secondary to osteosarcoma is rare. Cytologic examination may help reach the correct diagnosis if the smears and cellblock sections are carefully evaluated for certain helpful cytomorphologic features, particularly osteoid matrix., (© 2020 Wiley Periodicals LLC.)

Emperipolesis is a physiologic or pathologic phenomenon characterized by the presence of intact viable cells within the cytoplasm of another cell. It has been described in normal tissues and in a variety of inflammatory and neoplastic lesions such as Rosai-Dorfman disease, tumors, hematopoietic disorders and rarely lymphomas. Emperipolesis by mesothelial cells is rare. Few cases of mesothelial emperipolesis of neoplastic lymphocytes in pleural effusions involved by lymphomas have been reported in the literature. Its etiopathogenesis and significance are controversial and speculative. We report a case of a 36-year-old man who presented with cough, chest pain, breathing difficulty, pericardial, and bilateral pleural effusions secondary to mediastinal T-lymphoblastic lymphoma. Pleural fluid cytology slides and cell block sections showed numerous single dispersed neoplastic lymphoblasts with occasional giant multinucleated mesothelial cells with emperipolesis of lymphocytes. The background showed scattered and clumped apoptotic karyorrhexis debris and reactive mesothelial cells. Cell block immunohistochemistry showed CD3, CD5, CD7, CD10, CD99, and TdT positive lymphocytes, consistent with involvement by T-lymphoblastic lymphoma. The giant cells were positive for cytokeratin, calretinin and WT1 confirming their mesothelial origin. Lymphoid effusions with emperipolesis may raise a potential diagnostic pitfall because they may morphologically be confused with other inflammatory and neoplastic lesions. This cell-in-cell phenomenon can be a helpful clue in the differential diagnosis of lymphocyte-rich effusions since it has been described in association with lymphomas. It might shed some light on the lymphocyte-mesothelial interaction and the potential phagocytic antigen-presenting properties of mesothelial cells under certain circumstances., (© 2020 Wiley Periodicals LLC.)

Mycobacterium avium-intracellulare complex (MAIC) is a nontuberculous opportunistic infection in immunocompromised patients. Involvement of the gastrointestinal tract (GIT) is usually part of a disseminated disease in AIDS patients with a low CD4 count, however with standard antiretroviral therapy (ART), a localized presentation is more likely. It can affect any part of the GIT, mostly the duodenum and typically as patches. Incomplete or refractory ART for HIV-strains, therapy-related side effects, noncompliant or incomplete treatment to previous MAIC infections, superimposed complications and comorbid opportunistic infections may result in atypical clinical, endoscopic and histopathologic manifestations. We performed a retrospective review study retrieving cases of MAIC in duodenal endoscopic biopsy. We found five cases of MAIC in HIV/AIDS patients. They were males with an average age of 40-years. They showed different histopathologic features, variable patterns of MAIC-histiocytic infiltrates, and varying intensity of intracellular acid-fast positive bacilli. Enterocytes vacuolization and transepithelial elimination were also observed. Three cases were associated with cytomegalovirus and cryptococcal infections. A case was complicated by lymphangiectasia-associated protein-losing enteropathy. Initially, three cases were morphologically missed. Ziehl-Neelsen stain helped reach the correct diagnosis. Pathologists have an important role in patients' management by guiding clinicians to the correct diagnosis. Pathologists should be aware of these different histopathologic manifestations, their potential pitfalls, look for certain helpful clues complemented with multiple levels and special stains. In particular, AFB stains are mandatory in all mucosal biopsy specimens from HIV/AIDS patients regardless of their appearances., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Benign endometrial calcifications with or without bone fragments are uncommon clinicopathologic findings. They can be detected during pelvic ultrasonography or as incidental pathologic findings. They have been found to be associated with infertility and menstrual anomalies in young adult patients and in symptomatic postmenopausal women with endometrial atrophy and endometrial polyps. Its exact etiology is unknown, its pathogenesis is controversial, and its clinical importance is not fully validated. We performed a retrospective review study over 7 years and found 11 (0.4%) cases of benign endometrial calcifications. The mean patient age was 45.2 years (range = 20-66 years). All of the women complained of menstrual abnormalities and 4 complained of infertility. Six had a previous procedure of abortion, 2 had oral contraceptive pills, and 4 a course of progesterone therapy. Their size and morphology varied from heterogeneous microcalcifications of variable appearances, shattered glassy chunks to detached bones. Four cases were associated with endometrial polyps, 1 with a placental site nodule, 1 with chronic endometritis, and 1 with endometrial hyperplasia. Most showed secretory endometrial tissue and ciliated cell metaplasia. Two cases showed atrophic endometrium. Etiology and pathogenesis are multifactorial and miscellaneous. Progesterone may play a role. Heterogeneous histomorphologic patterns may carry potential pitfalls. Pathologic recognition is clinically important to reassure clinicians in symptomatic postmenopausal women, alert gynecologists to a treatable albeit rare cause of infertility in younger women, and assist in patients' counselling. We also included cases of calcifications associated with endometrial malignancies to compare and contrast malignant endometrial calcifications with benign endometrial calcifications.

Langerhans cell histiocytosis (LCH) is a bone marrow-derived immature myeloid dendritic cell proliferative disorder with diverse clinical manifestations commonly involves bone, skin, lymph node and lung. Oral involvement is uncommon. Intraoral lesions can be the first sign of either a localized LCH or clinically undiagnosed systemic LCH, predates systemic manifestations of LCH, or an early indicator of recurrence in known cases. Clinically, it can be mistaken for primary oral and dental inflammatory, infectious and neoplastic lesions. Histologically, diagnostic challenges may arise because of the nature of oral and dental specimens, different tissue reaction patterns and variations in histomorphology of LCH. We performed a retrospective review study over 10 years. We searched for diagnosed cases of LCH. We retrieved and reviewed cases of LCH with oral involvement. We found 54 cases of LCH, four (7.4%) with oral involvement. The age range was between 1 and 27 years with an average age of 13.7 years. They were males. They were clinically confused with abscess, cysts, infection, granulation tissue and other neoplastic lesions. Histologically, they showed different histopathologic features including different patterns of necrosis, granulomas, allergic-like inflammation, superimposed infection, stomatitis, cyst and sinus formation, foreign body giant cell reaction, and foci mimicking lymphomas and metastasis. Certain cytologic features were helpful hints. In doubtful cases, immunohistochemistry helped confirm the diagnosis. Because of the multiple fragmented nature of oral specimens with different tissue reaction patterns, the diagnostic Langerhans cells may be missed or misinterpreted. Oral LCH may be confused with infectious, inflammatory, benign and malignant neoplastic lesions because of its variable clinical presentations and its heterogeneous histomorphologic features. Pathologists have an important role in guiding clinicians to the correct diagnosis and patients' management. They should be familiar with the different histomorphologic patterns to avoid pitfalls. Attention to certain morphologic features and immunohistochemistry should help resolve challenging cases., Competing Interests: Declaration of competing interest No conflict of interests or financial disclosure to be declared by the authors., (Copyright © 2020 Elsevier Inc. All rights reserved.)