American Journal of Dermatopathology最新文献

{"title":"Cutaneous Epithelioid Myxofibrosarcoma Arising in a Face: Case Report and Literature Review.","authors":"Ihar I Haiduk, Andrey Y Valkov","doi":"10.1097/DAD.0000000000003189","DOIUrl":"10.1097/DAD.0000000000003189","url":null,"abstract":"<p><strong>Abstract: </strong>Myxofibrosarcoma is a malignant fibroblastic neoplasm characterized by cellular pleomorphism, myxoid stroma, distinctive curvilinear vessels, nonspecific immunophenotype, and complex karyotype. The epithelioid variant is a rare subtype composed of atypical cells featuring abundant eosinophilic cytoplasm and vesicular nuclei, closely mimicking nonmesenchymal malignancies. We report an exceptionally rare case of cutaneous epithelioid myxofibrosarcoma on the face of a 70-year-old man. The patient presented with a progressively enlarged cheek mass. Histopathologic examination revealed a dermal and subcutaneous tumor with a multinodular growth pattern and significant heterogeneity. It featured peripheral low-grade areas with myxoid stroma and curvilinear vessels and a central high-grade component (>50%) composed of solid sheets of epithelioid cells with severe nuclear atypia, prominent macronucleoli, and a high mitotic rate (>20 mitoses per 10 HPF). Tumor cells were focally positive for smooth muscle actin but negative for melanocytic, epithelial, myoepithelial, and lymphoid markers. CD34 highlighted the characteristic curvilinear vasculature of the tumor. Molecular analysis showed no mutations in BRAF, NRAS, or KIT genes, ultimately resulting in the diagnosis of high-grade epithelioid myxofibrosarcoma (FNCLCC grade 3). No recurrence or metastasis occurred within 9 months of follow-up. This case underscores the diagnostic challenge of cutaneous sarcomas in the head and neck region and highlights the necessity of a multimodal approach for an accurate diagnosis.</p>","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":"378-382"},"PeriodicalIF":1.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146020589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Onychopapilloma Is a Nail Bed Onycholemmal Papilloma: A Clinical and Histological Study of 56 Cases, Including Seborrheic Keratosis-Like Lesions.","authors":"Christophe Perrin","doi":"10.1097/DAD.0000000000003054","DOIUrl":"https://doi.org/10.1097/DAD.0000000000003054","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Abstract: &lt;/strong&gt;Onychopapilloma (OP) is a benign tumor of the nail. In all studies of the literature including the World Health Organization new classification of nail tumor, OP is proposed as a tumor originating in the distal matrix and defined histologically by its onychogenic property as \"matrix metaplasia of the nail bed.\"The aim of this study is to clarify the origin and type of keratinization of OP, to emphasize the application of clear histological criteria according to the type of surgical procedure, to present new clinical and histological subtypes of OP, and to discuss the differential diagnosis.Eighty-six cases were available for clinicopathologic review. Detailed clinicopathological analysis could be performed on 56 cases.In addition to the classic clinical presentations of longitudinal erythronychia, longitudinal leukonychia, longitudinal melanonychia, 2 cases presented an unusual band pattern in the form of xanthonychia. Histological interpretation was more difficult for samples obtained by tangential longitudinal excision than for those obtained by longitudinal monobloc excision. The superficial eosinophilic layer of the nail bed was either clearly identified by its round to oval nuclei or showed features simulating a keratogenous zone by foci of irregularly contoured pycnotic nuclei. In all cases, the so-called matrix metaplasia of the nail bed corresponded to an onycholemmal keratinization with 2 types of cornified cells: clear cells either parakeratotic or orthokeratotic, and eosinophilic cells. The clear orthokeratotic cornified cells sometimes simulated abnormal enlarged onychocytes. The onychogenic marker including hair related keratin (HK) 31, HK85, HK86, LEF-1, and beta-catenin were not expressed in the nail bed. The samples obtained by tangential longitudinal excision frequently showed incomplete or complete deepithelialization. In incomplete deepithelialization, 2 clues suggested a diagnosis of OP: numerous filiform superficial papillae and remnants of nail bed epithelium with a superficial eosinophilic layer. In complete deepithelialization, only examination of the nail plate allowed the diagnosis to be established. Loss of the organization of the suprabasal layers, dyskeratosis, and keratinocytes with clear cytoplasm were occasionally observed. However, the absence of nuclear atypia confirmed by the normal expression of Ki67 and p53 ruled out in situ onycholemmal carcinoma/malignant OP. Two new histological subtypes have been observed. OP with lesions resembling seborrheic keratosis. OP with an overexpression of CD10 simulating the stroma of OM. Nail clipping has proven to be potentially useful in the differential diagnosis between OP with seborrheic keratosis-like lesions and onychogenic tumor such as onychocytic matricoma and onychomatricoma. In contrast to the thick nail plate perforated by cavities of onychogenic tumors, OP was characterized by a focal thin nail plate with longitudinal groove. On excis","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":"48 5","pages":"337-353"},"PeriodicalIF":1.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147730584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Case of Darier Disease With p.N767S Mutation in ATP2A2 Successfully Treated With Upadacitinib.","authors":"Zhaojun Sun, Linlin Bao","doi":"10.1097/DAD.0000000000003242","DOIUrl":"10.1097/DAD.0000000000003242","url":null,"abstract":"","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":"410-411"},"PeriodicalIF":1.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146214881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Extranodal Rosai-Dorfman Disease With Increased IgG4-Positive Plasma Cells Involving the Breast: A Case Report With Review of the Literature.","authors":"Raymond Chimatira, Raisa Wessels","doi":"10.1097/DAD.0000000000003195","DOIUrl":"10.1097/DAD.0000000000003195","url":null,"abstract":"<p><strong>Abstract: </strong>Rosai-Dorfman disease (RDD) is a rare histiocytic disorder that most commonly affects lymph nodes but can also present in extranodal sites, including the breast. Immune-related RDD may be associated with increased plasma cells, with a significant proportion of the plasma cells expressing IgG4. These cases typically lack the other features of IgG4-related disease. We report a case of a 20-year-old woman who presented with a painless mass in the left breast. Prior biopsy was diagnosed as RDD with increased plasma cells. Ultrasound scan showed a well-circumscribed hypoechoic hypervascular solid subcutaneous mass with preservation of the surrounding breast parenchyma. Clinical assessment and imaging showed no evidence of regional lymphadenopathy or involvement of other organ systems. A wide local excision was performed. The excision showed a firm, unencapsulated fibrotic subcutaneous nodule. The histopathology revealed an expansion of the subcutaneous tissue, characterized by sheets of large histiocytes with round-to-oval nuclei and abundant pale to eosinophilic cytoplasm, set against a background of lymphoplasmacytic inflammation and stromal fibrosis. Several histiocytes demonstrated emperipolesis. The lesion was completely excised with clear margins. Immunohistochemistry showed that the histiocytes were positive for S100 and CD68, and negative for CD1a and AE1/AE3. The morphology and immunohistochemistry confirmed the diagnosis of extranodal RDD limited to the subcutaneous tissue of the breast. Extranodal RDD involving the breast is exceedingly rare and can mimic carcinoma both clinically and radiologically. Accurate diagnosis requires histologic and immunohistochemical confirmation.</p>","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":"391-396"},"PeriodicalIF":1.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145795532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benign Sweat-Gland Tubular Adenoma Harboring an MYBL1::NFIB Fusion Gene.","authors":"Jean Kanitakis, Françoise Descotes, Denis Jullien","doi":"10.1097/DAD.0000000000003208","DOIUrl":"10.1097/DAD.0000000000003208","url":null,"abstract":"<p><strong>Abstract: </strong>Sweat gland (SG) neoplasms encompass a wide variety of benign or malignant adnexal skin tumors differentiating into the various segments of SG. Their diagnosis and classification are often difficult, and have relied mainly on histologic and immunohistochemical criteria. Several genomic alterations have been more recently discovered in SG tumors, and have been used as additional diagnostic criteria. Among them, fusions of the MYBL1 or the MYB gene (namely MYB::NFIB or MYBL1::NFIB ) have been detected in a significant proportion of cutaneous and extracutaneous (breast and salivary gland) adenoid cystic carcinomas (AdCC), and have been regarded specific of this tumor type. We report here an exceedingly rare case of a benign neoplasm diagnosed as benign tubular SG adenoma that was unexpectedly found to harbor a MYBL1::NFIB fusion gene. This case expands the spectrum of SG tumors driven by fusions of MYBL1 , and challenges the specificity of MYBL1 fusions for cutaneous AdCC.</p>","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":"383-386"},"PeriodicalIF":1.0,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145901574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cutaneous T-Cell Lymphoma-Like Eruption from Trimethoprim-Sulfamethoxazole.","authors":"Carole Bitar, Alexys Wright, Alyssa Guillory, Natalya Gallaga, Ghaidaa Majari, Andrea Murina","doi":"10.1097/DAD.0000000000003307","DOIUrl":"https://doi.org/10.1097/DAD.0000000000003307","url":null,"abstract":"<p><strong>Abstract: </strong>Cutaneous pseudolymphoma is a benign reactive process that comprises a heterogeneous group of entities that resembles lymphoma clinically and/or histologically. This condition can be idiopathic or caused by drugs, infections, or foreign agents. Cutaneous pseudolymphoma could belong to the B-cell type, the T-cell type, or be mixed. The multiple presentations raise a significant diagnostic challenge and require clinicopathologic correlation and follow-up. This case report presents the clinical, histopathologic, immunophenotypic, and genetic findings of a cutaneous T-cell lymphoma-like eruption from trimethoprim-sulfamethoxazole in a 55-year-old female systemic lupus patient.</p>","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147788206","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Novel PDZRN3::BRAF Fusion as Potential Driver Mechanism in BAP1-inactivated Melanocytoma.","authors":"Yanhong Yu, Thomas Sabljic, Jose-Mario Capo-Chichi, Zaid Saeed Kamil","doi":"10.1097/DAD.0000000000003303","DOIUrl":"https://doi.org/10.1097/DAD.0000000000003303","url":null,"abstract":"<p><strong>Abstract: </strong>BAP1 (BRCA 1-associated protein 1)-inactivated melanocytic tumor (BIMT) is a melanocytic neoplasm characterized histologically by large epithelioid cells and is commonly associated with a conventional nevus component. The defining molecular alteration is inactivation of the BAP1 gene. Initiating mutations in BIMT include BRAF p.V600E, or less commonly RAS mutations and fusions involving RAF1. In this article, we report a case of BIMT with a BAP1 mutation and a novel PDZRN3::BRAF fusion. Histologic examination revealed an intradermal melanocytic neoplasm with nests and single units of large, atypical epithelioid cells with abundant amphophilic-eosinophilic cytoplasm, well-defined cell borders, large vesicular nuclei, and prominent nucleoli. Frequent binucleated and multinucleated melanocytes were present. There was no associated conventional nevus component. Scattered mitotic activity were identified. No evidence of maturation, necrosis, or lymphovascular or perineural invasion was seen. The lesional cells were immunoreactive for SOX10, Melan A, and HMB45 (focal, minimal, and weak), and were negative for PRAME. There was patchy loss of expression of p16 and complete loss of BAP1 expression. Molecular analysis demonstrated BAP1 mutation and a novel fusion involving PDZRN3::BRAF. Our finding expands our current understanding of the molecular landscape and pathogenesis of BIMT.</p>","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147718769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vascular Proliferation in Biopsies from Active Lichen Planopilaris as a Novel Pathologic Finding.","authors":"Anna Beyryumova, Julio A Diaz-Perez, Paolo Romanelli, Mariya Miteva","doi":"10.1097/DAD.0000000000003304","DOIUrl":"https://doi.org/10.1097/DAD.0000000000003304","url":null,"abstract":"","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147718732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Squamous Cell Carcinoma Arising in a Lobomycosis Ulcer: A Rare Presentation.","authors":"Kinan M Hayani, Omar P Sangüeza, Rute F Lellis","doi":"10.1097/DAD.0000000000003302","DOIUrl":"https://doi.org/10.1097/DAD.0000000000003302","url":null,"abstract":"","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147693294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ALK-Negative Systemic Anaplastic Large Cell Lymphoma With Multifocal Cutaneous Involvement Responding to Brentuximab Vedotin.","authors":"Matthew S Abad, Flordeliz Abad-Casintahan, Mark Ernest A Casintahan","doi":"10.1097/DAD.0000000000003301","DOIUrl":"https://doi.org/10.1097/DAD.0000000000003301","url":null,"abstract":"<p><strong>Abstract: </strong>Systemic anaplastic large cell lymphoma with cutaneous involvement can mimic other malignancies and delay treatment. A 71-year-old Filipino woman had 18 months of minimally symptomatic plaques and nodules; a right-hip nodule enlarged to an 8 × 8 × 5-cm mass. She underwent radical wide excision of the right-hip mass and scalp nodules; only the hip specimen was submitted for histopathology and was read as a malignant spindle cell tumor favoring alveolar rhabdomyosarcoma, with rapid recurrence at the hip and scalp surgical sites. On referral, she had plaques and nodules, crusted scalp lesions, and lymphadenopathies. Repeat biopsies from scalp and recurrent hip lesions showed a dermal-subcutaneous infiltrate of large atypical lymphocytes with mitoses and periadnexal/intravascular involvement; immunohistochemistry was CD30/CD3/CD45 positive and ALK/EMA negative, consistent with ALK-negative systemic ALCL with cutaneous involvement. Staging revealed stage IV disease with extranodal metastases and elevated LDH. After a dose of ifosfamide/etoposide elsewhere, therapy was revised to ifosfamide, carboplatin, and etoposide plus brentuximab vedotin, with marked improvement by 2 cycles and cutaneous resolution by 5; she died of cardiopulmonary failure before the sixth cycle. This case underscores generous sampling, focused immunohistochemistry, and staging; negative ALK/EMA does not exclude systemic disease, and CD30-directed therapy can yield rapid cutaneous responses.</p>","PeriodicalId":50967,"journal":{"name":"American Journal of Dermatopathology","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2026-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147693285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}