Journal of Cutaneous Pathology最新文献

A 68-year-old man with a history of diffuse large B-cell lymphoma (DLBCL) with cutaneous involvement presented with a new, rapidly growing, exophytic, bleeding tumor. Histopathologic and immunophenotypic characterization was consistent with a diagnosis of histiocytic sarcoma (HS). A subsequent lymph node biopsy also yielded a diagnosis of HS. Genetic analysis of this patient's original DLBCL bone marrow specimen and subsequent lymph node HS specimen identified identical p.G13D KRAS mutations. This case highlights, to our knowledge, the first case of systemic DLBCL with cutaneous involvement linked to transdifferentiated cutaneous HS by identical KRAS mutations. We also include a systematic review of cutaneous HS cases, identifying only two cases with underlying hematologic transdifferentiation. The distinct clinical morphology, histopathologic characteristics, and immunohistochemical markers associated with each of these entities highlight a very rare and unique example of histiocytic transdifferentiation in the context of a hematologic malignancy.

Acute febrile neutrophilic dermatosis, also known as Sweet syndrome, is an inflammatory skin condition characterized by the rapid onset of painful, erythematous plaques or nodules with neutrophilic infiltrate on histology. Rarely, acellular bodies surrounded by vacuolated spaces have been noted within the neutrophilic infiltrate, mimicking Cryptococcus infection. Despite these histological findings, the cryptococcoid variant of Sweet syndrome is not an infectious process. This delineation is essential for the initiation of proper treatment. Here, we present a patient with cryptococcoid Sweet syndrome with concomitant hydralazine-induced ANCA vasculitis, which has seldom been reported in the literature.

The study of dermatopathology is integral to the educational curricula for budding dermatologists and pathologists. Over the past decade, instruction in dermatopathology has rapidly evolved with the advent of slide scanners, virtual microscopy, social media, and online slide libraries. Recently, the Association of Professors of Dermatology (APD) met to discuss effective approaches for trainee education in dermatopathology given this new breadth of resources available. In this article, we conduct a scoping review of the literature discussing educational methods in dermatopathology, present strategies gleaned from the recent APD meeting, and highlight effective takeaways for structuring residency dermatopathology curricula.

Sclerotic fibroma (SF), initially described as a cutaneous manifestation of Cowden syndrome (CS), is an uncommon, well-circumscribed tumor characterized by sclerotic, hyalinized collagen bundles. Originally considered a sclerotic variant of benign fibrous histiocytoma (BFH), most SFs express FXIIIA, and despite this, there is limited investigation of other histiocytic markers. Additionally, SF-like changes in BFH and other cutaneous lesions may create diagnostic pitfalls. Nonetheless, consistent expression of CD34 and CD99, in close histomorphological correlation, supports the diagnosis of SF. To date, approximately 11 intraoral SFs have been reported, none associated with CS. We present an immunohistochemical analysis of a typical SF in the buccal mucosa of a 46-year-old male without signs of CS. Immunohistochemistry showed positivity for vimentin, CD34, CD99, collagen IV (focal), and α-SMA (focal). Notably, CD68, CD163, FXIIIA, and lysozyme were also positive, suggesting a histiocytic population infiltrating the stroma. This case reinforces that histomorphology, along with CD34 and CD99 immunoprofile, is essential to distinguish SF from BFH and other sclerosing mesenchymal neoplasms. Furthermore, our findings raise the possibility that a subset of SFs may harbor a histiocytic component, which could contribute to its pathogenesis or reflect a reactive stromal component.

Primary cutaneous aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma (PCAECTCL) is a rare and aggressive malignancy, with limited documented cases in pediatric patients. This report presents a unique case of a 9-year-old female with PCAECTCL, characterized by widespread erythematous annular lesions that exhibited an indolent clinical course that lasted four years after the development of the initial lesion, contrasting with the typically rapid progression seen in adults. Histopathological and immunohistochemical analyses revealed an atypical CD8+ T-cell infiltrate with marked epidermotropism, loss of CD2 and CD5 expression, and positivity for cytotoxic markers TIA-1 and granzyme B. Molecular studies identified a PCM1::JAK2 gene fusion, linking the disease to JAK/STAT pathway dysregulation, which is a finding previously unreported in pediatric PCAECTCL. Despite partial responses to topical therapies, oral prednisone, and methotrexate, the disease persisted, highlighting therapeutic challenges. This case underscores the importance of molecular profiling in PCAECTCL and suggests potential utility for JAK inhibitors like ruxolitinib.

Verruciform xanthoma (VX) is a rare lesion most often seen in the oral mucosa or anogenital region, most commonly characterized histologically by verrucous epithelial hyperplasia and foamy histiocytes in the papillary dermis. While VX has been reported in association with inflammatory dermatoses such as lichen planus and lichen sclerosus, its occurrence in the context of hidradenitis suppurativa (HS) has not been previously documented. In this case we present a 56-year-old man with long-standing, Hurley Stage 3 HS affecting the gluteal region. Following surgical excision of a draining sinus tract, histopathology revealed a squamous-lined follicular cyst consistent with HS, with approximately 10% of the cyst lining displaying features characteristic of VX, including papillomatous acanthosis, parakeratosis with neutrophils, and underlying foamy macrophages. Retrospective review of prior HS specimens did not show similar changes. This case expands the histologic spectrum of HS and suggests that chronic inflammation may promote secondary verruciform xanthomatous changes within follicular cysts. Although mutations in the cholesterol biosynthesis gene NSDHL have been linked to VX, no lichenoid or syndromic features were observed in our patient, supporting an inflammatory rather than genetic etiology. Recognition of VX-like changes in HS is important to avoid misdiagnosis as squamous cell carcinoma and further elucidates the complex epithelial remodeling in chronic inflammatory dermatoses.

Benign and malignant tumors derived from myoepithelial cells represent a rare group of tumors that may arise from salivary gland as well as breast, lung, and more rarely, skin. Cutaneous lesions showing myoepithelial origin include benign mixed tumor of skin (chondroid syringoma) in addition to much less common tumors composed entirely of myoepithelial cells, including benign myoepithelioma and malignant myoepithelial carcinoma. Variability in morphologic and phenotypic findings may result in a diagnostic challenge, especially in pure myoepithelial neoplasms. While some myoepithelial neoplasms may demonstrate overtly benign or malignant features, there are also reports of metastases arising from tumors lacking malignant histopathologic features, further challenging classification and prognostication of this group of tumors. Myoepithelial tumors arising within adnexal and salivary gland neoplasms have been reported. We report a unique case of myoepithelial carcinoma arising in association with a precursor syringocystadenoma papilliferum.

Balamuthia mandrillaris is a rare cause of cutaneous amebiasis that can progress to central nervous system infection, almost always resulting in death. It is a free-living, opportunistic ameba found globally in dust, soil, and freshwater that can infect people of all ages regardless of the status of the host immune system. Herein, we report a case of B. mandrillaris infection in Canada in an 83-year-old man presenting to the hospital with altered mental status and a chronic wound of 4-year duration. A skin biopsy of the chronic wound revealed extensive dermal granulomatous and mixed inflammatory infiltrate with abundant multinucleated giant cells. Inspection of multiple level sections revealed structures concerning for amebic trophozoites. After the patient's death, lesional tissue from the skin and brain was sent to the Centers for Disease Control (CDC) for further subtyping, which confirmed B. mandrillaris as the causative organism. This case raises awareness for this organism as a possible cause of cutaneous infections and highlights the necessity for dermatopathologists and pathologists alike to have a heightened suspicion for amebic infections when non-specific granulomatous inflammation is identified in the skin.

Primary cutaneous NUT adnexal carcinoma is an emerging provisional tumor entity characterized by NUTM1 rearrangement with fusion partners different from poroid neoplasms. These tumors should be distinguished from NUT carcinomas with a histopathologic appearance of poorly differentiated squamous cell carcinoma, which tend to behave more aggressively and demonstrate a widespread anatomic distribution. Since fewer than 20 cases of NUT adnexal carcinoma have been reported in the literature, we report herein another case to enhance our knowledge of the spectrum of clinical and pathologic features associated with this tumor. This case is characterized by an unusual clinical course. The lesion was present and slowly progressed over the course of 13 years prior to biopsy and excision. The tumor was composed of epithelial and myoepithelial elements with a range of features, including ductal, cribriform, and solid, with papillary, secretory, and keratocystic changes. The patient underwent wide local excision and sentinel lymph node biopsy, which revealed metastatic tumor. Molecular testing identified a BRD3-NUTM1 fusion, confirming the diagnosis of NUT adnexal carcinoma. The patient remains disease-free at 1-year follow-up without further therapy.