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Pyoderma gangrenosum (PG) is a rare necrotizing neutrophilic dermatosis driven by monokines and cytokines elaborated by monocytes and autoreactive T cells, respectively. Th1-mediated autoimmune disorders and myeloproliferative disease are among the potential disease associations. More recently, certain medications were implicated, including TNF-alpha inhibitors, rituximab, and IL-17A inhibitors, such as secukinumab, where the development of PG is held to represent a cutaneous immune adverse effect. We present two patients who developed an autoinflammatory syndrome resembling PG in the setting of drug therapy with agents exhibiting an IL-17A inhibitory effect. The drugs were erunumab in one and secukinumab in the other. One patient received the anti-calcitonin gene-related peptide targeted therapy, erenumab, for migraine prophylaxis. While this drug has not been previously implicated in the development of PG, it can cause IL-17A blockade. The other patient was on secukinumab, a monoclonal antibody that selectively targets IL-17A. We documented a microenvironment enriched in IL-17A, emphasizing that the blockade impacts the functionality of the receptor as opposed to a quantitative reduction in IL-17A production by T cells. Qualitative functional IL-17A blockade could result in a paradoxical increase in IL-23, a pro-inflammatory cytokine that may contribute to the influx of neutrophils pathogenetically implicated in PG., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Diseases reflective of multiorgan vascular injury of diverse etiology, peripheral nerve disease, dysautonomia syndromes, and intravascular lymphoma may exhibit abnormalities on a normal skin biopsy that may be instrumental in establishing a diagnosis. A retrospective review of our database was conducted to uncover cases where a normal skin biopsy was performed to rule in or out such systemic diseases as complement-driven thrombotic microvascular disease (including atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, and severe or critical COVID-19), systemic capillary leak syndrome, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) intravascular B cell lymphoma, small fiber neuropathy, dysautonomia syndromes, and mast cell activation syndrome. Among the special studies were immunohistochemical staining to detect C5b-9, CD56, and myxovirus resistance protein A, as well as mast cell, B and T cell markers. Characteristic patterns were critical in establishing diagnoses such as : increased C5b-9 microvascular deposition in the deltoid area (atypical hemolytic uremic syndrome, posttransplant thrombotic microangiopathy, catastrophic antiphospholipid antibody syndrome, and severe or critical COVID-19); enhanced type I interferon signaling (systemic capillary leak syndrome); ultrastructural arteriopathic changes (CADASIL); reduced cutaneous autonomic innervation in the lower extremities (small fiber neuropathy and postural orthostatic tachycardia syndrome); presence of intravascular lymphocytes on biopsy of abdominal, thigh, and buttock skin (intravascular B cell lymphoma); and a higher than normal density of mast cells in the absence of other inflammatory cell types (mast cell activation syndrome). The skin is clearly a critical window for understanding extracutaneous disease, a concept well exemplified by the myriad of diseases suggested by the microscopic and/or ultrastructural examination of clinically normal skin and therefore establishing the normal skin biopsy as an important tool for understanding certain extracutaneous reactive, neoplastic and paraneoplastic syndromes as well as small fiber neuropathy., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Abstract: Malignant atrophic papulosis/Köhlmeier-Degos disease was first described in 1941 by Köhlmeier in an anecdotal case report that described a young man who presented with extensive multiple intestinal perforations and a papular skin rash. Köhlmeier-Degos disease represents a unique vasculopathy targeting both the microvasculature and the arterial system. One of its most characteristic features is reflected by the discrete multifocal depressed porcelain lesions involving the skin and gastrointestinal tract. The pathological findings are striking and can be broadly categorized into those that are vascular in nature versus extravascular matrix production in the context of extensive extravascular hyaluronic acid and collagen deposition. A dynamic evolutionary morphology is observed not only clinically but also histologically. The microvascular alterations are particularly evident in the skin and are characterized by endothelial cell necrosis with subsequent endothelial cell detachment accompanied by intraluminal fibrin deposition, defining a thrombogenic microangiopathy that in later stage lesions is typically pauci-inflammatory. The arterial lesions are very distinctive and include significant neointimal proliferation with vascular luminal occlusion by amorphous plugs of collagen intimately admixed with platelets. Pathogenetically enhanced type I interferon signaling and endothelial cell injury mediated by the membranolytic attack complex (ie, C5b-9) are key in the evolution of the thrombotic microvascular and obliterative fibrosing arteriopathic changes. We describe a case of Köhlmeier-Degos disease that developed in the setting of tumor necrosis factor (TNF)-alpha inhibitor therapy with the drug golimumab. The clinical features, light microscopic findings, and a pathophysiologic paradigm based on the critical role of TNF-alpha in controlling the type I interferon response are discussed., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Microvascular thrombosis is key to the pathogenesis of calciphylaxis. C5b-9-mediated microvascular injury reflective of complement pathway activation could be a key pathophysiologic event., Methods: We conducted a retrospective multicenter study of 24 patients who have had biopsy-supported calciphylaxis from the 2010-2022 data base from Emory where C5b-9 immunohistochemistry (IHC) had not been conducted and the 2019-2023 data base from Cornell where C5b-9 IHC was done as part of the routine calciphylaxis work up. IHC for C5b-9 on lesional biopsy specimens was assessed and correlated with routine light microscopic findings and clinical features., Results: Most of the patients in our study had uremic calciphylaxis associated with obesity, diabetes, dialysis, hypertension, hyperparathyroidism and elevated serum phosphorus. Most patients did not have defined procoagulant and/or hyperviscosity states. The vascular pathology was predominantly limited to the subcutaneous fat and ranged from a calcific intimal arteriopathy to microvascular thrombosis with endothelial injury with or without endothelial calcification. In most cases (ie, in excess of 80%), there was prominent deposition of C5b-9 within the vasculature including the microvasculature and arteries of the fat at least localized to injured vessels suggesting a causal association. In about 40% of cases, there was evidence of systemic complement pathway activation revealed by concurrent dermal microvascular C5b-9 deposition., Conclusions: Calciphylaxis is characterized by subcuticular vascular changes that reflect an interplay between complement triggered endothelial cell injury, resultant vascular thrombosis, and subsequent abluminal calcification. Complement inhibition therapy defines a potential intervention that should be explored., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

T cell dyscrasias that demonstrate a proclivity for the subcutaneous fat include atypical lymphocytic lobular panniculitis, lupus profundus, and primary subcutaneous T cell lymphoma, including subcutaneous panniculitis-like T cell lymphoma (SPTCL). We encountered two patients who developed fever and indurated abdominal erythema at their peginterferon alfa-2a injection sites. Biopsies showed an atypical CD8 positive, granzyme positive, CD5 negative, MXA negative lymphocytic lobular panniculitis, diagnostic of SPTCL. Peginterferon alfa-2a was held in both patients. One patient received chemotherapy with an excellent response, while the other continued to have progressive disease. Peginterferon alfa-2a is known to significantly elevate serum MXA, which may induce high levels of MXA expression at the injection site, creating a microenvironment for the development of lupus profundus, which may eventuate into SPTCL. In summation, a potential risk of peginterferon alfa-2a injections is the development of SPTCL potentially arising in a background of an exogenous interferon triggered lymphocytic panniculitis.

Competing Interests: LJG has served as an investigator for and/or received research support from Helsinn Group, J&J, Mallinckrodt, Kyowa Kirin, Soligenix, Innate, Merck, BMS, and Stratpharma; on the speakers’ bureau for Helsinn Group and J&J; and on the scientific advisory board for Helsinn Group, J&J, Mallinckrodt, Sanofi, Regeneron, and Kyowa Kirin. OA, CMM, MHT, ERG, BAL, CMS and LMF have no conflicts of interest to declare.

Background and Objectives: TEMPI (telangiectasias, elevated erythropoietin and erythrocytosis, monoclonal gammopathy, perinephric fluid collections, and intrapulmonaryshunting) syndrome is a rare multisystemic disease classified as a monoclonal gammopathy of cutaneous significance. The pathogenesis and etiology of TEMPIare not well known because of the rarity of this disorder. Although telangiectasias are the hallmark of this syndrome, skin biopsies are rarely performed. We aim to further characterize TEMPI syndrome through the evaluationof a skin biopsy., Methods: We reviewed the histopathology and immunophenotypic profile of a skin biopsy from a 53-year-oldwoman diagnosed with TEMPI syndrome. Other components of her syndromic complex included an IgA myeloma, elevated vascular endothelial growth factor (VEGF), and erythrocytosis., Results: A biopsy showed prominent vascular ectasia with some degree of microvascular basement membranezone thickening. Our patient had a reduction in neoplastic plasma cell burdenand clearing of her telangiectasias following myeloma directed treatment., Conclusions: TEMPI can beviewed as a reactive vascular paraneoplastic syndrome in the setting of a plasma cell dyscrasia. Elaboration of VEGF from neoplastic plasma cells is likely pathogenetically implicated and appears to be a common link that explains other vascular lesions associated with monoclonal gammopathy syndromes., (© 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Abstract: Mucha-Habermann disease (MHD) is an inflammatory skin disease characterized by polymorphous eruptions of erythematous, necrotic macules that have been reported for similarities to cutaneous T-cell lymphoma. Febrile ulceronecrotic MHD (FUMHD) represents a severe variant of MHD, marked by ulcers, hemorrhagic bullae, and systemic symptoms. Herein, we report a case of a severely atypical lymphomatoid expression of FUMHD associated with hemophagocytic lymphohistiocytosis (HLH). A previously healthy 21-year-old woman was admitted to the hospital with a rapidly progressive necrotic papular rash. Physical examination revealed right orbital swelling, bilateral hemorrhagic auricular bullae, and multiple ulcerative purpuric papulonodules on the trunk, face, and extremities. Biopsy indicated a dermal and subcutaneous infiltrate of atypical CD8 + lymphocytes with loss of CD5 and reduction in CD7 expression, along with features of lymphomatoid vasculitis. A diagnosis of a severely atypical lymphomatoid expression of FUMHD was made. The patient also met 7 of 9 HLH-2004 criteria, leading to a diagnosis of HLH. Positron emission tomography/computed tomography, flow cytometry, and rheumatologic workup were unremarkable. Treatment with an eight-week course of etoposide and dexamethasone for HLH led to rapid clinical improvement. Over time, her skin lesions regressed and eventually scabbed over to leave hyperpigmented scars, confirming the diagnosis of MHD. She has remained stable, off therapy for 4 years. Although potentially fatal, FUMHD often exhibits favorable outcomes and may resolve without recurrence, as in our patient. FUMHD should be considered in the differential diagnosis for patients presenting with cutaneous CD8 + necrotizing angiocentric lymphoproliferative disease complicated by HLH., Competing Interests: C. Chen, L.M. Fahmy, C.M. Schreidah, C.M. Magro, and L.J. Geskin have given substantial contributions to the conception and design of the manuscript. C. Chen and L.M. Fahmy conducted chart review and literature review and prepared the original draft of the manuscript. C.M. Magro analyzed the histopathology slides and provided the included photomicrographs. L.J. Geskin provided direct care in the diagnosis and treatment of the patient. All authors contributed to the review and editing of the manuscript. All authors read and approved the final version of the manuscript. L.J. Geskin has served as an investigator for and/or received research support from Helsinn Group, J&J, Mallinckrodt, Kyowa Kirin, Soligenix, Innate, Merck, BMS, and Stratpharma; is on the speakers' bureau for Helsinn Group and J&J; and is on the scientific advisory board for Helsinn Group, J&J, Mallinckrodt, Sanofi, Regeneron, and Kyowa Kirin. C. Chen, L.M. Fahmy, C.M. Schreidah, and C.M. Magro have no conflicts of interest to declare., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Individual reports have described lymphoproliferative disorders (LPDs) and cutaneous lymphomas emerging after administration of the COVID-19 vaccine; however, the relationship between reactions and vaccine types has not yet been examined., Objective: Determine if there are cases of cutaneous LPDs associated with certain COVID-19 vaccines and their outcomes., Methods: We analysed PubMed, the Vaccine Adverse Events Reporting System (VAERS), and our database for instances of biopsy-proven LPDs following COVID-19 vaccines., Results: Fifty cases of biopsy-proven LPDs arising after COVID-19 vaccination were found: 37 from medical literature, 11 from VAERS and two from our institution. Geographical distribution revealed the most cases in the United States, Italy, and Greece, with single cases in Spain, Colombia, Canada, Japan, and Romania. The average age of patients was 53; with a slight male predominance (male-to-female ratio of 1.5:1). The Pfizer-BioNTech vaccine was associated with LPDs in 36/50 (72%) cases, aligning with its 70% share of the global vaccine market. Histopathology revealed CD30+ in 80% of cases. The most prevalent form of LPD was lymphomatoid papulosis (LyP, 30%). All reported cases produced favourable outcomes (either complete or near-complete remission). Therapeutic approaches ranged from observation to treatment with steroids, methotrexate, or excision., Conclusion: LPDs after COVID-19 vaccination appear in the context of the same vaccines (proportionally to their global market shares), share clinical and pathological findings, and have indolent, self-limited character., Competing Interests: LJG has served as an investigator for and/or received research support from Helsinn Group, J&J, Mallinckrodt, Kyowa Kirin, Soligenix, Innate, Merck, BMS, and Stratpharma; on the speakers’ bureau for Helsinn Group and J&J; and on the scientific advisory board for Helsinn Group, J&J, Mallinckrodt, Sanofi, Regeneron, and Kyowa Kirin. ERG, BDK, CMS, LMF, OA, DQ, MHT, CMM have no conflicts of interest to declare., (© 2024 The Authors. Skin Health and Disease published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.)

Competing Interests: LJG has served as an investigator for and/or received research support from Helsinn Group, J&J, Mallinckrodt, Kyowa Kirin, Soligenix, Innate, Merck, BMS, and Stratpharma; on the speakers’ bureau for Helsinn Group and J&J; and on the scientific advisory board for Helsinn Group, J&J, Mallinckrodt, Sanofi, Regeneron, and Kyowa Kirin. OA, MHT, ERG, BAL, CMS, LMF, CC and CMM have no conflicts of interest to declare.

Individual reports described lymphoproliferative disorders (LPDs) after COVID-19 vaccination; however, the relationship between cases is unexamined. We aim to determine if there are cases of cutaneous LPDs associated with COVID-19 vaccination and their outcomes. We present a review of world literature, vaccine registries, and two unreported cases of LPDs after COVID-19 vaccination. Review of the medical literature, VAERS, and our two cases reveal predominance of Pfizer-BioNTech vaccine, younger patients, and males. All cases resulted in favorable outcomes. Approximately 84% of cases demonstrated CD30+ positivity in their skin biopsies, suggesting that an antigenic trigger may lead to a type IV adaptive immune response, with clonal expansion of CD30+ T-cells and subsequent oncogenic mutational hits eventuating in transient LPDs. LPDs after COVID-19 vaccination appear in the context of the same vaccines (proportionally to their global market shares), share clinical and pathological findings, and have indolent, self-limited character.

Tebentafusp is a bispecific protein that recently underwent FDA approval for the treatment of metastatic uveal melanoma that functions by redirecting cytotoxic T cells to glycoprotein-100, a protein highly expressed in melanoma. Although clinical trials have demonstrated that rashes are common in the first few days of treatment, little is known about skin reactions that develop later in the treatment course. Herein, we describe a type IV hypersensitivity reaction and vitiligo-like depigmentation that developed six weeks into treatment and discuss the possible mechanisms underlying these reactions. The type IV hypersensitivity reaction resolved without intervention within seven weeks of onset, suggesting that tebentafusp can be safely continued in select patients who develop this cutaneous reaction.

Clonally restricted, non-epidermotropic, low-grade, CD8-positive T-cell infiltrates of the skin was recognized as a unique form of indolent CD8-positive lymphoproliferative disease in 2007 when it was first called primary cutaneous indolent CD8-positive lymphoid proliferation. More recently, the designation of primary cutaneous acral CD8-positive T-cell lymphoproliferative disorder has been used. It is unique as a cutaneous lymphoproliferative disorder because of relative uniformity in its clinical presentation and histomorphology. It has been recognized as having an interesting predilection for the ear and acral sites, characteristically presenting as a solitary lesion. The basic morphology is one characterized by a non-epidermotropic, tumefactive infiltrate of well-differentiated, noncerebriform, atypical, small- to intermediate-sized lymphocytes that exhibit a specific phenotype characterized by CD8 and TIA positivity in concert with a distinct perinuclear Golgi staining pattern for CD68. The typical presentation is in the context of a solitary lesion, which can be treated surgically or with local irradiation. We describe in detail two very unusual cases that expand the clinical spectrum of this condition given the non-acral localization, the multiplicity of lesions to involve the trunk and extremities, and, in one case, the stable but recalcitrant course over 30 years. In addition, the second patient developed paraneoplastic dermatomyositis. We also retrospectively review our database for other cases that represent the entity of primary cutaneous acral CD8-positive T-cell lymphoproliferative disorder and review the literature focusing on non-acral cases. Nomenclature evolution from its first recognition in 2007 to the present is discussed., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Published by Elsevier Inc.)

Certain T-cell lymphomas exhibit unique homing properties of the neoplastic lymphocytes for the subcutaneous fat. There are two primary forms of subcutaneous panniculitic lymphomas of T-cell origin. One falls under the designation of primary cutaneous gamma-delta T-cell lymphomas (PGD-TCL) whereby there is dominant involvement of the fat defininng a panniculitic form of PGD-TCL. The neoplastic cells are of the gamma-delta subset and are either double negative for CD4 and CD8 and/or can express CD8. They often have an aggressive clinical course. The other form of panniculitic T-cell lymphoma falls under the designation of subcutaneous panniculitis-like T-cell lymphoma (SPTCL). It represents a subcutaneous lymphoma derived from CD8+ T cells of the alpha-beta subset and typically has an indolent course. These two forms of panniculitic T-cell lymphoma exhibit overlapping histologic features with lupus profundus (LP), a putative form of panniculitic T-cell dyscrasia. We present three cases of PGD-TCL of the fat in the setting of lupus erythematosus (LE) (two cases) and dermatomyositis (DM) (one case), respectively. There were concurrent features of LE and DM in their lymphoma biopsies in two cases while a prior biopsy in one was interpreted as LP. In this latter case, the LP diagnosis presaged the diagnosis of panniculitic PGD-TCL by three years. One patient diagnosed with panniculitic PGD-TCL had hemophagocytic syndrome after developing a lupus-like complex including certain supportive serologies such as antibodies to double-stranded DNA following initiation of statin therapy. The second patient presented with PGD-TCL and concomitant features of anti-nuclear matrix 2 (NXP2) DM. The third patient presented in 2003 with LP and overlying skin features of acute LE, initially responding to Plaquenil, and then four years later was diagnosed with PGD-TCL heralded by Plaquenil treatment resistance. Two of the patients died of their lymphoma. All biopsies showed a characteristic histopathology of PGD-TCL. In two cases, the PGD-TCL was associated with overlying LE-cutaneous findings; another case had skin changes of lymphocyte-rich DM. In two cases, the MXA stain was strikingly positive, the surrogate type I interferon marker that is typically upregulated in biopsies of LE and DM. There are eight prior reported cases describing SPTCL with concomitant cutaneous changes of LE. In six cases there was an established history of LE, including LP responding initially to Plaquenil, similar to one of our cases. In the context of SPTCL or panniculitic PGD-TCL, panniculitic T-cell lymphomas can be associated with concomitant clinical and histologic features of LE or DM, including an upregulated type I interferon signature. Identifying histologic features associated with either of these prototypic autoimmune conditions should not be considered exclusionary to diagnosing any panniculitic T-cell lymphoma. A clinical, histomorphologic, and pathophysiologic continuum exists with LP, SPTCL and panniculitic PGD-TCL., Competing Interests: Declaration of Competing Interest The authors declare no conflicts of interest., (Copyright © 2023. Published by Elsevier Inc.)

Introduction: Onycholemmal carcinoma (OC) is a rare subtype of squamous cell carcinoma (SCC) that originates from the epithelium of the nail bed. It is characterized by distinct histopathologic features including small clusters of atypical squamous epithelium devoid of a granular layer, with abrupt onycholemmal keratinization., Case Presentation: We present a case of a 75-year-old male with right thumbnail onycholysis, yellow-green nail plate discoloration, as well as bleeding and purulence of the lateral nail fold. Histopathologic evaluation revealed high-grade squamous dysplasia, small clusters of severely atypical epithelial cells, and a pattern of abrupt keratinization consistent with the diagnosis of SCC carcinoma with onycholemmal features. GMS and PAS staining indicated concomitant onychomycosis. Pathologic analysis also disclosed residual SCC and concomitant amyloidosis, possibly light chain related and hence reflective of his underlying multi-organ lymphoplasmacytic lymphoma. The patient subsequently underwent Mohs micrographic surgery., Conclusion: Clinical presentation of nail unit SCC with onycholemmal features is highly variable, making differentiating between similarly presenting benign and malignant nail disorders particularly challenging. This case report demonstrates clinical and histopathological features of nail unit SCC with onycholemmal features to improve diagnosis and management., Competing Interests: Kelita Waterton and Dr. Magro have no conflicts of interest. Dr. Lipner has served as a consultant for Hoth Therapeutics, Ortho-Dermatologics, Moberg Pharmaceutricals, and BelleTorus Corporation., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Introduction: Localized longitudinal erythronychia is defined as a single nail with a longitudinal red band extending the length of a nail plate. It has a broad differential of benign and malignant etiologies, and is rarely due to benign vascular proliferations., Case Presentation: We present a unique case of nail unit arteriovenous hemangioma presenting as longitudinal erythronychia of the left thumbnail in a 76-year-old male. The band was 6 mm and encompassed over 40% of the surface area of the nail plate. Dermoscopy showed red bands that were regular in terms of color, but not thickness or spacing. Due to concern for an amelanotic melanoma, a longitudinal excision was performed. Histopathology was consistent with a diagnosis of nail unit arteriovenous hemangioma., Conclusion: Arteriovenous hemangiomas were rarely present in the nail unit. They can be present as a blue or red nodule/macule, or as longitudinal erythronychia. Diagnosis often requires an excisional biopsy, with histopathology notable for a proliferation of multiple thick- and thin-walled vascular structures lined by a flattened endothelium. Our case emphasizes the need to consider vascular proliferations, such as arteriovenous hemangioma, in the differential diagnosis of longitudinal erythronychia., Competing Interests: Authors J.K.H. and C.M.M. have no conflicts of interest to declare. Author S.R.L. has served as a consultant for Hoth Therapeutics, Ortho Dermatologics, BelleTorus Corporation, and Moberg Pharmaceuticals., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Competing Interests: L.J.G. has served as an investigator for and/or received research support from Helsinn Group, J&J, Mallinckrodt, Kyowa Kirin, Soligenix, Innate, Merck, BMS, and Stratpharma; is on the speakers' bureau for Helsinn Group and J&J; and is on the scientific advisory board for Helsinn Group, J&J, Mallinckrodt, Sanofi, Regeneron, and Kyowa Kirin. C.M.S., L.M.F., B.A.L., and C.M.M. have no conflicts of interest to declare.

Onychomycosis is a common nail infection. Terbinafine-resistant dermatophyte infections pose an emerging global public health concern, but few cases have been described in the United States. We retrospectively reviewed and characterized clinical, histopathological, and mycological features of patients with mycologically confirmed onychomycosis who failed oral terbinafine treatment for onychomycosis at a U.S. academic nail referral center and ascertained for terbinafine-resistant isolates. During 1 June 2022-31 January 2023 at Weill Cornell Medicine in New York City, USA, 96 patients with mycologically confirmed onychomycosis were treated with oral terbinafine. Among 64 patients with adequate follow-up, 36 had clinical or complete cure. Of 28 patients who failed treatment, 17 underwent terbinafine resistance testing. Trichophyton rubrum with terbinafine resistance-conferring mutations was isolated from two patients. Overall, terbinafine failures for onychomycosis were relatively common, with some cases associated with terbinafine-resistant T. rubrum infections. These findings underscore the need for a clinical awareness of this emerging problem and public health efforts to monitor and prevent spread. We highlight the importance of diagnostic testing and species identification for onychomycosis patients and the increasingly important role of fungal identification and susceptibility testing to guide therapy.

Background: Primary cutaneous marginal zone lymphoma (PCMZL) is a form of indolent lymphoproliferative disease where the disease is largely a cutaneous confined process. It is typically a neoplasm composed of post germinal small B-cells and light chain restricted plasma cells in a background of reactive T-cell hyperplasia and benign germinal centers. Rarely a significant degree of large cell infiltration occurs warranting the categorization as blastic marginal zone lymphoma., Materials and Methods: We reviewed our data base over a time period of 2016 to 2022 for cases diagnosed as blastic MZL. Twelve cases were identified. The clinical records and pathological data were reviewed., Results: Nine of the cases represented de novo forms of blastic MZL while in three cases there was a prior history of MZL. Multifocal cutaneous disease was not uncommon and one quarter of the cases had evidence of extracutaneous dissemination. All patients except three achieved remission with varied therapeutic interventions depending on the extent of the disease ranging from conservative re-excision to chemotherapy. No patient died from lymphoma. Light microscopically, there was evidence of a background of conventional MZL in the majority of cases. The large cell component was typically characterized by multiple micronodular aggregates throughout the dermis although in three cases there was a striking diffuse large cell component as the dominant infiltrate. Phenotypically, a third of the cases showed either CD5 or CD23 positivity amidst neoplastic B cells. Significant staining for BCL-2 was noted in the majority of cases tested while extensive MUM-1 positivity was observed in half of the cases tested. Kappa or lambda light chain restriction was seen in most. The Ki67 proliferation index exceeded 30 % in all cases. There was C-MYC positivity in two cases. While most cases did not detect cytogenetic abnormalities, one case had multiple cytogenetic hits that are associated with diffuse large B cell lymphoma. Next generation sequencing showed a Ten-eleven translocation 2 mutation in the earlier biopsy prior to transformation and in the later biopsy after transformation along with an additional B2M mutation in the transformed biopsy. Both types of mutations are very uncommon but held to contribute to tumor progression in the setting of diffuse large B cell lymphoma., Conclusion: Blastic MZL is associated with a more aggressive clinical course. Even when there is disseminated disease patients while not always cured did not have a fatal course in this series. The light microscopic findings are reproducible. The background of MZL, identification of larger cells in significant numbers without a follicle center phenotype, at times expressing CD5 or CD23 with variable positivity for MUM1, BCL-2 and C-MYC and a high proliferation index define the pathology in most. Certain cytogenetic abnormalities and genetic mutations implicated in large cell transformation into a diffuse large B cell lymphoma are seen in blastic MZL with earlier biopsies prior to transformation potentially harboring at risk genetic mutations., Competing Interests: Conflicts of interest None., (Copyright © 2022. Published by Elsevier Inc.)

Lichen sclerosus (LS) is a cutaneous disease of unknown etiology that often involves the vulva or foreskin but also can affect extragenital sites. Regardless of the anatomic site, the histomorphology and presumably pathogenesis are similar. Perhaps a clue to the pathophysiology of LS lies in its frequent association with morphea, specifically, when occurring in an extragenital context. In our experience a striking feature evident in established lichen sclerosis (LS) is one of superficial vascular drop out whereby residual vessels exhibited endothelial cell necrosis and microvascular basement membrane zone thickening, the latter reflective of antecedent episodes of microvascular injury. We sought to understand the pathophysiology that underlies the distinct vascular changes and in doing so, shed light on the pathogenesis of LS. We examined 44 cases of LS over a period of 2019 to 2021. We were able to obtain past medical histories in 34 of the 44 cases. Regarding pathological assessment, the predominant focus was on microvascular changes. We assessed the role of C5b-9 mediated vascular injury in the pathogenesis of the vasculopathy and enhanced type I interferon signaling in vessels given the morphologic semblance to the select interferonopathy syndromes, namely fibrosing dermatomyositis and Kohlmeier Degos disease. We examined the expression of CMV DNA and protein based on prior observations in an earlier study that isolated early protein expression in the microvasculature in the setting of LS and scleroderma. From a clinical perspective, the most striking association was an older age at the time of diagnosis (mean age of 62 years and median age of 61.5 years) and the presence of vascular comorbidities of diabetes, hypertension, and hyperlipidemia in almost 80% of cases. All cases showed significant microvascular changes in the superficial corium with the most frequent findings being those of significant basement membrane zone reduplication and vascular drop out. A number of cases showed prominent microvascular deposits of C5b-9 in the zone of hyalinizing fibrosis or subjacent to the discernible table of fibroplasia in the absence of enhanced type I interferon signaling. In no case were there viral cytopathic changes associated with CMV affecting the endothelium. The studies that encode CMV DNA or protein did not show a significant role for CMV reactivation in endothelium in the majority of the studied cases. It is concluded that the pathophysiology of LS includes a microvascular injury syndrome within the papillary dermis. The mechanism of endothelial cell injury is complement mediated at least in part and could reflect an adaptive immune response targeting endothelium indicative of classic complement pathway activation when coexisting with morphea or occurring in younger individuals. A non-immune based endothelial dysfunction and complement mediated injury unrelated to antibody driven classic complement pathway activation are more likely pathogenetically in the setting of certain diseases like diabetes mellitus and hypertension. Vascular drop out can be explained by the diminished endothelial progenitor pool needed to repopulate the damaged microvessels in certain settings like hypertension and diabetes., Competing Interests: Declaration of competing interest None., (Copyright © 2022. Published by Elsevier Inc.)

Idiopathic Systemic Capillary Leak Syndrome (ISCLS), also known as Clarkson's Syndrome, is due to primary fluid and protein leak across capillaries that leads to an accumulation of interstitial fluids and cardiovascular collapse from intravascular hypovolemia. Viral infections are a putative trigger of these episodes. ISCLS is typically associated with a monoclonal gammopathy. Here we present four patients with idiopathic systemic capillary leak syndrome. The cohort consists of three men and one woman who range in age from 55 to 72 years old. All of the patients had a monoclonal gammopathy. Two patients had viral triggers. Biopsies of normal skin were examined throughout all phases of the disease. During an acute attack, we identified perivascular mixed CD4+ and CD8+ T cell lymphocytic infiltrates in the superficial dermis. We observed significant microvascular deposits of C5b-9 and upregulation of type I interferon signaling in endothelium along with reduced serum levels of complement during very active disease. We also identified deposits of immunoglobulin along the dermal epidermal junction mirroring the monoclonal immunoglobulin isotype implicated in each patient. During a post treatment recovery or mild disease phase there was reduced inflammation and decreased amounts of C5b-9 and type I interferon expression. Sudden onset capillary leak syndrome reflects enhanced endothelial cell permeability as a unique form of endothelial injury mediated by the combined effects of complement pathway activation and upregulation of type I interferon signaling on endothelium., Competing Interests: Declaration of competing interest None., (Copyright © 2022. Published by Elsevier Inc.)

Lymphomatoid papulosis (LYP), the most common primary cutaneous CD30-positive lymphoproliferative disorder, is heralded by multiple papular and nodular lesions at anatomically discontiguous cutaneous sites. The histologic patterns are protean. An uncommon form of LYP is one that is anatomically confined. Cases of unilesional LYP, regional LYP, and persistent agmination of LYP were encountered in the routine and consultative practices of Weill Cornell Medicine, Division of Dermatopathology. The clinical presentation, outcomes, light microscopic findings, and phenotypic profile are reviewed. There were 10 cases of LYP presenting as solitary plaques or nodules primarily occurring in older patients and without a relevant medical history in most. Most cases occurred at an acral site with many localized to the foot; the morphology was one of a necrotizing angiocentric type E pattern and borderline type C morphology. Two of the unilesional patients in our series went on to develop mycosis fungoides, one at the initial site of unilesional type A LYP, and the other at a discontiguous site. Excluding one case, the solitary lesions underwent complete regression; after the lesions regressed, some cases had no apparent recurrence. The second anatomically confined variant of LYP in our series was regional LYP exhibiting a type E morphology in two cases and a hybrid type A and granulomatous eccrinotropic morphology in one case. There was no subsequent development of lymphoma, nor was there any spread to additional anatomic sites. The final category was persistent agmination of LYP, whereby the agminated papules of LYP were superimposed on a plaque of cutaneous T-cell lymphoma represented by mycosis fungoides in two and follicular helper T-cell lymphoma in one. In conclusion, anatomically confined LYP defines an uncommon form of LYP, but it is an important one to recognize because the histology can be worrisome despite an indolent clinical course. The clinical presentation, the infrequent association with lymphoma/leukemia, and histology are similar to conventional LYP, although there appears to be a greater tendency for complete regression without recurrence, excluding cases of persistent agmination of LYP whereby the clinical course warrants categorization as a form of cutaneous T cell lymphoma (CTCL)., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Cutaneous leukocytoclastic vasculitis (LCV) has a distinctive clinical and light microscopic presentation; however, the etiologic basis of LCV is varied. Most cases are attributable to immune complex deposition within a vessel wall and represent an Arthus type III immune complex reaction. The prototypic immunoreactant profile is characterized by granular deposits of components of complement activation in concert with immunoglobulin within the cutaneous vasculature. We encountered nine patients with vasculitic and/or vesiculobullous clinical presentations exhibiting an LCV in association with an immunoreactant profile characterized by homogeneous linear deposits of immunoglobulin along the dermal epidermal junction in a fashion resembling an autoimmune vesiculobullous disease. Among the clinical presentations were palpable purpura, urticarial vasculitis, and vesiculobullous eruptions with supervening purpura. Two patients with Crohn disease presented with classic palpable purpura with biopsy-proven LCV, and direct immunofluorescence (DIF) studies demonstrated linear immunoglobulin G (IgG) with floor localization on the salt-split skin assay. Four patients with systemic lupus erythematosus (SLE) showed purpuric vesiculobullous lesions, with evidence of a neutrophilic interface dermatitis and LCV in three of the four. The remaining patient had urticarial nonbullous lesions showing small-vessel vasculitiswith a neutrophilic interface dermatitis. In all of the patients with SLE, DIF studies showed linear immunoglobulin deposits within the basement membrane zone (BMZ). These constellation of findings clinically, light microscopically, and by immunofluorescence were those of a vasculitic presentation of bullous systemic lupus erythematosus. Two patients had linear IgA disease, which was drug induced in one and paraneoplastic in the other, and the dominant morphology on biopsy in both cases was an LCV. One patient microscopically demonstrated drug-associated and eosinophilic enriched LCV with DIF studies showing striking linear deposits of IgG suggestive of bullous pemphigoid, which was consistent with a vasculitic presentation of drug-induced bullous pemphigoid. In all cases, typical granular vascular immunoglobulin and complement deposition compatible with immune complex mediated vasculitis was observed. It is likely that local immune complexes derived from BMZ antigen bound to antibody are pathogenically relevant. We propose the designation of linear vasculitis for this unique scenario of LCV and linear immunoglobulin epidermal BMZ staining, which in some cases represents a vasculitic presentation of conventional autoimmune vesiculobullous disease., (Published by Elsevier Inc.)

Introduction: Kohlmeier-Degos (K-D) disease is a rare obliterative vasculopathy that can present as a benign cutaneous form or with potentially malignant systemic involvement. The gastrointestinal tract is most frequently involved in systemic disease and mortality is often related to bowel perforations. Herein, we provide information to providers and patients regarding gastrointestinal K-D symptomology, pathology, treatment, and diagnosis, with a focus on the importance of timely diagnostic laparoscopy. We present three new cases of gastrointestinal K-D to highlight varying disease presentations and outcomes. BODY: Based on reviewed reports, perforation is preceded by at least one gastrointestinal symptom: abdominal pain/cramping, anorexia/weight loss, vomiting, diarrhea, nausea, gastrointestinal bleeding, obstipation, constipation, and abdominal fullness. Perforation most commonly occurs in the small intestine and often results in sepsis and death. Although underutilized, laparoscopy is the most sensitive and specific diagnostic technique, demonstrating serosal porcelain plaques similar to those on the skin and characteristic for K-D. The combination of eculizumab and treprostinil is presently the most effective treatment option for gastrointestinal K-D. The pathology of gastrointestinal K-D is characterized by an obliterative intimal arteriopathy eventuating in occlusive acellular deposits of mucin and collagen along with an extravascular pauci-cellular sclerosing process resembling scleroderma confined to the subserosal fat. C5b-9 and interferon-alpha are both expressed in all caliber of vessels in the affected intestine. While C5b-9 blockade does not prevent the intimal expansion, enhanced type I interferon signaling is likely a key determinant to intimal expansion by, causing an influx of monocytes which transdifferentiate into procollagen-producing myofibroblast-like cells., Conclusion: Prompt laparoscopic evaluation is necessary in any K-D patient with an abdominal symptom to facilitate diagnosis and treatment initiation, as well as to hopefully decrease mortality. Those with gastrointestinal K-D should start on eculizumab as soon as possible, as onset of action is immediate., (© 2022. The Author(s).)

Abstract: Paraneoplastic granulomatous disease occurs in approximately 7.3% of patients with non-Hodgkin lymphoma, most commonly among patients with chronic lymphocytic leukemia (CLL). These lesions are often reported to appear similar to sarcoidosis in clinical presentation and under light microscopy. However, comprehensive descriptions of the cytomorphologic characteristics of these paraneoplastic granulomas are lacking, and the mechanisms involved in their formation remain ill-defined. Noninfectious dermal granulomatous reactions have also been reported in many primary immunodeficiencies, including common variable immune deficiency and ataxia-telangiectasia. We present a case of noninfectious CD8+ predominant granulomatous dermatitis with ocular involvement occurring in the setting of CLL and marked hypogammaglobulinemia. Based on the analysis of shared factors in patients with primary immunodeficiencies and CLL, we conclude that the presence of pan-humoral immunodeficiency could itself be a risk factor for developing a CD8+ lymphogranulomatous reaction. This report and associated discussion evince that CD8+ predominant granulomatous reactions, distinct from sarcoidosis, may represent a previously unappreciated segment of the paraneoplastic granulomas observed in hematologic malignancies., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: The authors declare no conflict of interest.