Journal of Cutaneous Pathology最新文献

{"title":"Fatally Metastatic Diagnostic Pitfall: Pseudolymphomatous Epithelioid Cutaneous Angiosarcoma Arising From an Ulcerative Scalp Injury","authors":"Michelle Y. Zhu,&nbsp;Mahyar Khazaeli","doi":"10.1111/cup.14813","DOIUrl":"10.1111/cup.14813","url":null,"abstract":"<div>\u0000 \u0000 <p>Rare morphological variants of cutaneous angiosarcoma (AS) can be diagnostically challenging. Angiosarcoma located on the head and scalp of the elderly has been associated with especially poor prognosis. We report a difficult diagnostic pitfall of pseudolymphomatous AS variant with overlapping features of epithelioid variant and aberrant immunohistochemistry staining, arising on an ulcerative scalp lesion in a 79-year old woman. Initial histopathological exam showed extensive cutaneous necrosis with prominent dermal inflammation within which, scattered large cells were CD31 positive and CD34 negative. After cutaneous lymphoma was ruled out, these large cells within the inflammatory infiltrate were determined to be dermal histiocytes and initial biopsy was diagnosed as benign. Subsequent re-biopsy showed similar features and was also called benign. Post-mortem re-review found the large cells were positive for ERG and formed solid clusters and papillae in some areas. A diagnosis of pseudolymphomatous epithelioid AS was rendered. Autopsy demonstrated lung nodules to be metastatic AS, consistent with findings from scalp primary. Our case draws attention to multiple features that can confound angiosarcoma diagnosis, and we discuss the appropriate endothelial IHC panel to rule out angiosarcoma in this clinical context.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 7","pages":"469-473"},"PeriodicalIF":1.6,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144020953","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":"Primary Cutaneous Anaplastic Large Cell Lymphoma With TCR-γδ Expression: A Case Series of Eleven Patients of a Rare Immunophenotypic Variant","authors":"Anna Sarah Erem,&nbsp;Werner Kempf,&nbsp;Christina Mitteldorf,&nbsp;Melissa Pulitzer,&nbsp;Carlos A Torres-Cabala,&nbsp;Stefano Pileri,&nbsp;Socorro Maria Rodriguez Pinilla,&nbsp;Andrew L. Feldman,&nbsp;Alejandro A. Gru","doi":"10.1111/cup.14809","DOIUrl":"10.1111/cup.14809","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Primary cutaneous anaplastic large cell lymphoma (pcALCL) and lymphomatoid papulosis (LyP) are indolent CD30-positive lymphoproliferative disorders that rarely express TCR-γδ. However, primary cutaneous gamma-delta T-cell lymphoma (pcGDTCL), characterized by TCR-γδ expression on neoplastic cells, is a rare, aggressive cutaneous T-cell lymphoma with a poor prognosis. Accurate differentiation is essential due to distinct clinical behavior and treatment.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>We identified 11 TCR-γδ-positive pcALCL cases from internal and consultation files, verified by two cutaneous lymphoma experts, with clinicopathologic data recorded.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The median age was 68 years (range 38–95). Most cases presented as a single dermal lesion on the upper extremities. All were ALK-negative, CD30-positive (&gt; 90% tumor cells), TCR-βF1-negative, and diffusely TCR-γδ-positive. CD4−/CD8− (54.5%) and CD4+/CD8− (45.5%) immunophenotypes were observed. CD2 (63.6%) and CD3 (54.5%) were the most common T-cell antigens. Ulceration, inflammation (both 45.5%), and necrosis (36.4%) were frequent. Angiotropism, angiocentricity, and myxoid stroma appeared in one case; epidermotropism in two. Four of ten tested were <i>DUSP22</i>-rearranged, and TP63 was negative in all eight tested.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Most ALK-negative TCR-γδ-positive pcALCL were CD4−/CD8−, followed by CD4+/CD8−. <i>DUSP22</i> rearrangement occurred in 40% of cases, similar to reports in typical pcALCL. Its prognosis and the role of <i>DUSP22</i> are yet to be clarified.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 7","pages":"487-496"},"PeriodicalIF":1.6,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143811610","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":"Histopathologic Evaluation of Density and Depth of the Lymphoid Infiltrate in Clinically Defined Patches and Plaques in Early Stage Mycosis Fungoides","authors":"Juliette M. Kersten,&nbsp;Rosanne Ottevanger,&nbsp;Thom Doeleman,&nbsp;Pieter A. Valkema,&nbsp;Anne M. R. Schrader,&nbsp;Patty M. Jansen,&nbsp;Maarten H. Vermeer,&nbsp;Rein Willemze","doi":"10.1111/cup.14810","DOIUrl":"10.1111/cup.14810","url":null,"abstract":"&lt;p&gt;Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma (CTCL) [&lt;span&gt;1&lt;/span&gt;]. In most patients, MF runs an indolent clinical course for years to decades, but in approximately 25% of patients, progression to advanced-stage MF is observed [&lt;span&gt;2, 3&lt;/span&gt;]. The prognosis of MF depends on the type and extent of skin lesions and the presence of extracutaneous disease. Early-stage MF is characterized by the presence of patches and/or plaques covering less than 10% (stage IA) or 10% or more of the body surface area (stage IB). Several studies reported that patients presenting with both patches and plaques have a higher risk of progression to advanced-stage MF and a worse survival than patients presenting with only patches [&lt;span&gt;3-5&lt;/span&gt;]. Therefore, the distinction between patches and plaques is clinically relevant, but it can be difficult due to a lack of standardized and reproducible criteria [&lt;span&gt;6&lt;/span&gt;]. In the current classification system, differentiation between patches and plaques is based exclusively on clinical examination. Patches are defined as skin lesions without significant elevation or induration, while plaques are defined as skin lesions with elevation or induration [&lt;span&gt;7&lt;/span&gt;]. However, this definition is subjective and prone to considerable inter-observer variability [&lt;span&gt;6&lt;/span&gt;]. Previous studies on folliculotropic MF (FMF) found that a clinicopathologic approach, combining clinical and histopathological criteria, can facilitate the distinction between early and advanced plaque-stage disease [&lt;span&gt;8, 9&lt;/span&gt;]. At recent meetings, the question was raised whether histopathologic criteria, in particular the extent and depth of the infiltrates, could also facilitate the distinction between patches and plaques in classical MF. The infiltrates in plaques in classical MF are indeed generally denser and deeper than in patches [&lt;span&gt;6, 10&lt;/span&gt;]. However, studies investigating whether these differences may contribute to a more reliable distinction between patches and plaques have not been published thus far. In the present study, we investigated the extent and depth of the infiltrate in patches and plaques in classic MF to find out if these histopathological criteria can serve as an adjunct to differentiate between these two types of lesions.&lt;/p&gt;&lt;p&gt;Using a database of scanned HE stained sections obtained from pretreatment biopsies of patients with early-stage classical MF, 100 cases with variable extent and depth of the infiltrates were selected without knowledge of the clinical data. Corresponding clinical records and clinical images of the biopsied lesions were evaluated and, blinded to the histopathologic characteristics, scored as either patch or plaque by three individual dermatologists using ISCL/EORTC criteria described previously [&lt;span&gt;7&lt;/span&gt;]. In case of discrepancy (&lt; 5% of lesions) cases were discussed together and consensus was reached. In the total group of 100 cases with ear","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 6","pages":"406-409"},"PeriodicalIF":1.6,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cup.14810","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143803407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hypopigmented Junctional BAP1-Inactivated Melanocytoma: A Paradigm Shift","authors":"Ali Gunesch,&nbsp;Iwei Yeh,&nbsp;Timothy McCalmont,&nbsp;Elizabeth Berry,&nbsp;Gretchen Vanderbeek,&nbsp;Kevin P. White","doi":"10.1111/cup.14808","DOIUrl":"10.1111/cup.14808","url":null,"abstract":"<div>\u0000 \u0000 <p>Since their original description by Wiesner et al., the spectrum of clinical, histopathologic, and molecular findings of BAP1 (BRCA1-associated protein 1)-inactivated melanocytomas has been more fully characterized. Herein, we report an exceptional presentation of multiple junctional melanocytic BAP1-inactivated melanocytomas with a clinically hypopigmented appearance in a patient. Targeted DNA sequencing demonstrated the same <i>BAP1</i> frameshift mutation (<i>BAP1</i> p.R59f) in three different lesions. One of the specimens also displayed two truncating mutations in <i>NF1</i> (<i>NF1 p.Q129*</i> and <i>NF1 p.Q1801*</i>) at 8%–9% mutant allele frequency. To our knowledge, BIM confined entirely to the epidermis, and multiple BIMs presenting in hypopigmented fashion have not been widely reported previously.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 6","pages":"428-431"},"PeriodicalIF":1.6,"publicationDate":"2025-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143795508","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":"Clinicopathologic Features of Penile Ulceration in Malignant Atrophic Papulosis: A Case Report and Review of the Literature","authors":"Matthew H. Lanehart,&nbsp;Brooke Bertus,&nbsp;Patrick J. Bacaj,&nbsp;Michael S. Kolodney,&nbsp;Colleen J. Beatty","doi":"10.1111/cup.14805","DOIUrl":"10.1111/cup.14805","url":null,"abstract":"<div>\u0000 \u0000 <p>Degos disease, or malignant atrophic papulosis (MAP), is a rare vasculopathic disorder that commonly involves the skin, gastrointestinal tract, and central nervous system. Diagnosis is made through recognition of characteristic histopathologic features of cutaneous lesions. Here, we report a 58-year-old male who initially presented with a penile eschar exhibiting vascular dilation, hyalinization of superficial dermal vessels, and hemosiderin deposition. Later, he developed scattered erythematous papules with central porcelain-white scarring; biopsies of these lesions exhibited features histopathologically consistent with MAP, including wedge-shaped necrosis extending from the epidermis into the deep dermis, dermal mucinosis, and vascular occlusion. Our patient subsequently developed multiple bowel perforations and ultimately succumbed to the disease. Recognition of various distinctive histopathologic features, including the diverse findings associated with penile ulceration, is important for prompt diagnosis and early initiation of treatment. As such, we review the clinicopathologic features reported in penile ulcerations among patients with MAP.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 6","pages":"423-427"},"PeriodicalIF":1.6,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143779731","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":"Shifts in Cutaneous Melanocytic Tumor Diagnostic Terminology: Melanocytoma, MPATH-Dx V2.0 and the WHO Skin5.","authors":"Lyn M Duncan, David E Elder, Michael W Piepkorn, Stevan R Knezevich, Willeke A M Blokx, Marcus Bosenberg, Klaus J Busam, Richard Carr, Martin G Cook, Pedram Gerami, Jennifer Ko, Gilles Landman, Alexander J Lazar, Lori Lowe, Daniela Mihic-Probst, Birgitta Schmidt, Christopher R Shea, Richard A Scolyer, Xiaowei Xu, Joann G Elmore, Raymond L Barnhill","doi":"10.1111/cup.14788","DOIUrl":"https://doi.org/10.1111/cup.14788","url":null,"abstract":"<p><p>In this Special Issue of the Journal of Cutaneous Pathology in memory of Dr. Martin C. Mihm, Jr, we highlight his many contributions over more than 50 years to the catalog of specific melanocytic tumor terminology. Dr. Mihm was an active participant in the International Melanoma Pathology Study Group (IMPSG). Discussions led to proposed recommendations for changes in the terminology of melanocytic tumors and their standardized diagnostic reporting. Histopathological reports of melanocytic tumors provide critical information that guides patient counseling and therapy. Importantly the pathology report must relay whether the melanocytic tumor is benign, intermediate, or malignant, and when appropriate, indicate diagnostic and/or prognostic uncertainty. Recent shifts in diagnostic terminology include the recommended use of the term \"melanocytoma\" to describe a morphologically and genetically defined subset of intermediate risk melanocytic tumors with higher (although still very low) risk of progression compared with benign nevi. Melanocytomas are distinguished from melanocytic tumors of uncertain malignant potential (MELTUMP) which are histopathologically indeterminate or uncertain tumors. In the setting of a broad lexicon for the reporting of melanocytic tumors, an assessment tool has been developed to map existing diverse terminologies into distinct hierarchical classes. The Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) V2.0 provides a four-tiered classification scheme that is tiered by risk of tumor progression and recommended treatment. The purpose of this review is to report these shifts in diagnostic terminology, discussed and reviewed at the annual workshop of the IMPSG, in Edinburg, Scotland, in November 2022. This discussion included the use of the term melanocytoma, and the use of the MPATH-Dx V2.0 classification and terminology for melanocytic tumors. Dr. Mihm was diligent in his attention to specific terminology, in his memory we aim to recommend terminology that improves communication in the care of those diagnosed with melanocytic tumors.</p>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143779894","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":"Histopathologic Features in Vancomycin-Associated Drug-Induced Hypersensitivity Syndrome","authors":"Hannah B. Haberecht,&nbsp;Rachel L. Ziebart,&nbsp;Olivia C. Iverson,&nbsp;Austin Todd,&nbsp;Mark D. Davis,&nbsp;David A. Wetter,&nbsp;Julio C. Sartori-Valinotti,&nbsp;Hafsa M. Cantwell,&nbsp;Marian T. McEvoy,&nbsp;Nessa Aghazadeh Mohandesi,&nbsp;Afsaneh Alavi,&nbsp;Emma F. Johnson","doi":"10.1111/cup.14804","DOIUrl":"10.1111/cup.14804","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Drug-induced hypersensitivity syndrome (DiHS), or drug reaction with eosinophilia and systemic symptoms (DRESS), is a delayed and severe immune response to certain medications. We investigated vancomycin-induced DiHS/DRESS, notable for frequent and severe organ involvement, to describe its specific histopathology and the correlations between histopathologic and clinical findings.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A retrospective review was conducted to identify patients between 2006 and 2022 who received vancomycin, had archived skin biopsy specimens, and were scored as having probable or definite DiHS/DRESS. Clinical features were retrospectively collected, and biopsy specimens were reviewed by a board-certified dermatopathologist. A subset of histopathologic and clinical features was analyzed for statistical correlation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Twenty-three patients met the inclusion criteria. Most biopsy specimens (87%) showed an eczematous reaction pattern; 17 (74%) showed a secondary reaction pattern. Spongiosis (87%) and neutrophilic infiltration (91%) were common epidermal characteristics. The dermal inflammatory infiltrate was frequently superficial (87%) and consistently included plasma cells (96%). Eosinophils were present in the dermis in 70% of cases. Parakeratosis negatively correlated with liver involvement and positively correlated with desquamative rash. Epidermal lymphocytes were negatively correlated with the RegiSCAR score.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Vancomycin-associated DiHS/DRESS histopathology was characterized by a frequent eczematous reaction pattern, multiple coexisting reaction patterns, and epidermal neutrophilic infiltration.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 6","pages":"442-451"},"PeriodicalIF":1.6,"publicationDate":"2025-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143700450","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 Fluoroscopy-Induced Subacute Radiation Dermatitis Histologically Mimicking Sclerodermiform Lupus: Immunohistochemical Analysis of Cytotoxic Memory T-Cell Markers","authors":"Vidya Medepalli,&nbsp;Timar A. Mascio,&nbsp;Anthony Thompson,&nbsp;Marc Inglese,&nbsp;Pamela Padilla,&nbsp;Stephen Richardson,&nbsp;András Schaffer","doi":"10.1111/cup.14807","DOIUrl":"10.1111/cup.14807","url":null,"abstract":"<div>\u0000 \u0000 <p>The histological hallmark of fluoroscopy-induced subacute radiation dermatitis (FISARD) is basovacuolar interface reaction with satellite cell necrosis mediated by CD8+ cytotoxic T-cells. Most published cases are described in patients who had a single interventional exposure. Here we report a case of FISARD in a 78-year-old man who underwent two cardiovascular interventions within 2 months. Biopsy of the skin lesion on his left back revealed not only epidermal cytotoxic interface activity with superficial perivascular dermatitis but also deep perivascular and interstitial dermal lymphoid infiltrates and dermal sclerosis, features overlapping with lupus and inflammatory morphea. Immunohistochemistry revealed intraepidermal and dermal expression of CD3, CD8, TIA-1, and CD45RA, likely corresponding to terminally differentiated effector memory cytotoxic T cells (TEMRA). In contrast, expression of CD57, a marker of late memory T-cells implicated in scleroderma pathogenesis, was absent in the epidermis but present in the dermis. This case adds to the spectrum of histopathologic findings of FISARD possibly related to the cumulative radiation injury from multiple fluoroscopic procedures. Given the increasing use of fluoroscopy, recognition of this histopathological pattern could aid in the timely and accurate diagnosis of this condition. A potential role of memory CD8+ T-cells in disease pathogenesis is discussed.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 6","pages":"418-422"},"PeriodicalIF":1.6,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143692318","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":"Genomic and Transcriptomic Characterization of Protein Kinase C Fusion Melanocytic Neoplasms With Distinctive Hypopigmented Histomorphology: A Single-Institution Study","authors":"Aofei Li,&nbsp;Brandon Umphress,&nbsp;Carina Dehner,&nbsp;Ryan Jones,&nbsp;Keller Toral,&nbsp;Simon Warren,&nbsp;Ahmed K. Alomari","doi":"10.1111/cup.14801","DOIUrl":"10.1111/cup.14801","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Genomic fusions involving Protein Kinase C (<i>PKC</i> or <i>PRKC</i>) have been classically identified in a subset of melanocytic neoplasms with heavy melanin pigmentation as described in older series. They were recently reclassified from the pigmented epithelioid melanocytoma (PEM) category to the blue nevus (BN) category in the fifth edition of the World Health Organization (WHO) Classification of Skin Tumors.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Herein, we report a series of eight mostly hypopigmented <i>PRKC</i> fusion melanocytic tumors with novel comprehensive molecular characterization. Clinical, histopathologic, and immunohistochemical findings were reviewed. Next-generation sequencing (NGS) data on genomic and transcriptomic levels were explored.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Histomorphology showed a biphasic pattern with hypercellular areas and hypocellular areas with dense fibrotic stroma and collagen trapping. The clinical courses were uncomplicated after excisions. NGS revealed three cases of <i>PRKCB</i> fusion and five cases of <i>PRKCA</i> fusions. RNA differential analysis against six blue nevi showed a group of genes with significantly higher transcription levels and strong enrichment in the direct p53 effectors gene set. <i>PRKC</i> fusion tumors also demonstrated significantly stronger p53 IHC staining.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>We further expand the morphologic spectrum of <i>PRKC</i> fusion melanocytic tumors and provide insight into their morphologic identification. Our novel transcriptome-level findings provide insight into the nuanced molecular events and new evidence for classification.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 6","pages":"432-441"},"PeriodicalIF":1.6,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cup.14801","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143663622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Primary Cutaneous Neoplasm With Rhabdomyosarcomatous Differentiation and a Melanoma-Like Mutational Landscape","authors":"Maximillian A. Weigelt,&nbsp;Shinoj Pattali,&nbsp;Josephine K. Dermawan,&nbsp;Jennifer S. Ko,&nbsp;Karen J. Fritchie,&nbsp;Steven D. Billings","doi":"10.1111/cup.14806","DOIUrl":"10.1111/cup.14806","url":null,"abstract":"<p>Malignant melanoma (MM) is notorious for its wide range of morphologic variability. Rarely, MM may lose all melanocytic markers and adopt the morphologic and immunophenotypic characteristics of a different neoplasm in a process known as trans-differentiation (TMM). Distinguishing TMM from primary cutaneous neoplasms may be challenging and is often dependent on the identification of an adjacent conventional melanoma. In particularly difficult cases, molecular analysis may be helpful; TMMs are known to exhibit highly similar mutational landscapes to conventional melanomas (e.g., mutations in <i>NF1</i>, <i>NRAS</i>; variable <i>BRAF</i> V600E). Herein, we present an exceedingly rare case of likely TMM with rhabdomyosarcomatous differentiation in which high tumor mutational burden (TMB) was an important clue to the diagnosis. An 83-year-old woman presented with an 8.2 cm fungating mass on the upper arm. Biopsy revealed a sheet-like proliferation of mitotically active pleomorphic cells which were positive for myogenin/MyoD1 and negative for S100/SOX10. A diagnosis of epithelioid rhabdomyosarcoma was rendered. Subsequent axillary lymph node metastasis prompted whole exome sequencing, which revealed a molecular signature more indicative of MM, including: high TMB (19 mutations/Mb); ultraviolet mutational signature (i.e., preponderance of C&gt;T base changes); <i>TERT</i> promoter mutation; and <i>ARID2</i> mutation. After discussion at the interdisciplinary tumor board, a diagnosis of TMM was considered most likely, and the patient was initiated on pembrolizumab. Morphologic features more typical of MM than cutaneous sarcomas, such as tumor-infiltrating lymphocytes, junctional epidermal tumor nests, and satellitosis, may provide further clues to the accurate diagnosis of TMM, which has important prognostic and therapeutic implications for the patient.</p>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 6","pages":"414-417"},"PeriodicalIF":1.6,"publicationDate":"2025-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cup.14806","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143639598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}