Journal of Cutaneous Pathology最新文献

{"title":"Detecting Monkeypox Virus by Immunohistochemistry","authors":"Spencer Ng,&nbsp;Carla Stephan,&nbsp;Mytrang Do,&nbsp;Denise Frosina,&nbsp;Achim Jungbluth,&nbsp;Klaus J. Busam,&nbsp;Linglei Ma","doi":"10.1111/cup.14776","DOIUrl":"10.1111/cup.14776","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Mpox (formerly known as monkeypox), a zoonotic disease caused by <i>Monkeypox</i> virus (<i>MPXV</i>), has become an international outbreak since May 2022. Mpox often presents with a mild systemic illness and a characteristic vesiculopustular skin eruption. In addition to molecular testing, histopathology of cutaneous lesions usually shows distinctive findings, such as epidermal necrosis, balloon degeneration, papillary dermal edema, and focal dermal necrosis, which have proven helpful in the diagnosis of mpox. Viral cytopathic changes with areas of multinucleation, smudging of the nuclei, and intracytoplasmic inclusions have also been described. Although useful, these features are relatively nonspecific. The use of a monoclonal antibody for immunohistochemical (IHC) staining of <i>MPXV</i> may be a useful tool in confirming mpox infection.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Three cases of PCR-confirmed mpox were biopsied and subjected to IHC staining with a monoclonal <i>MPXV</i>-specific antibody targeting viral envelope protein A29. As controls, cell lines transduced to express other <i>MPXV</i> viral antigens and samples of cutaneous viral infections involving <i>Molluscum contagiosum</i>, <i>Herpes simplex</i>, <i>Herpes zoster</i>, or <i>Cytomegalovirus</i> were also subjected to IHC staining with this antibody.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>All three mpox patient biopsies performed on lesional skin subjected to <i>MPXV</i> IHC staining reliably detected viral infection in lesional skin with a diffuse cytoplasmic and focally nuclear staining pattern. No staining was seen in transduced cell lines expressing off-target <i>MPXV</i> viral antigens and in lesional skin of other common viral infections listed above.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>The monoclonal <i>MPXV</i>-specific antibody may be used as an adjunct tool to confirm mpox infection.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 3","pages":"244-249"},"PeriodicalIF":1.6,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cup.14776","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142854034","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":"Extensive Leg Ulcers in a Patient With Monoclonal Gammopathy","authors":"Carlos Manuel Martorell Moreau,&nbsp;Beatriz Bartolomé González,&nbsp;Alberto Danilo Escobar Oblitas,&nbsp;Carlos Saus Sarrias","doi":"10.1111/cup.14777","DOIUrl":"10.1111/cup.14777","url":null,"abstract":"<div>\u0000 \u0000 <p>A 60-year-old male was admitted from the emergency department with extensive leg ulcers and polyarticular joint pain. Cryocrystalglobulinemia was diagnosed through positive cryoglobulin studies and characteristic histopathological findings. Treatment with bortezomib led to complete clinical resolution. Cryocrystalglobulinemia poses diagnostic and management challenges, highlighting the importance of interdisciplinary collaboration for optimal patient care.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 3","pages":"173-176"},"PeriodicalIF":1.6,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142846843","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":"Cytokine Profiling of Erythroderma Biopsies Reveals Types 2 and 17 Immune Activation Status","authors":"Tatsiana Pukhalskaya,&nbsp;Mitchell Finkelstein,&nbsp;Dacia A. Miyake-Caballero,&nbsp;Michael T. Tetzlaff,&nbsp;Jeffrey P. North,&nbsp;Jarish N. Cohen","doi":"10.1111/cup.14775","DOIUrl":"10.1111/cup.14775","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Erythroderma is a dermatologic condition characterized by widespread red and scaly skin. The causes include, but are not limited to, psoriasis, eczema, drug eruptions, pityriasis rubra pilaris (PRP), and cutaneous T-cell lymphoma. Most of these are typified by Type 2 (e.g., eczema) or Type 17 (e.g., psoriasis) immune activation. However, since the clinicopathologic features of erythroderma can be nonspecific, assays that determine the underlying immune activation status are desirable.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>IL-13 RNA in situ hybridization and IL-36 immunohistochemistry were performed on 30 specimens of erythroderma, to ascertain Type 2 and Type 17 immune signatures, respectively.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>Specimens of erythrodermic psoriasis and PRP showed strong expression of IL-36 and less than one IL-13-positive cell per millimeter. Conversely, those of spongiotic dermatitis showed low expression of IL-36 and greater than one IL-13-positive cell per millimeter. Most specimens of spongiotic, psoriasiform dermatitis demonstrated low IL-36 expression and greater than one IL-13-positive cell per millimeter, but a subset showed high IL-36 expression and greater than one IL-13-positive cell per millimeter.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>We developed a Type 2/17 immune signature classifier based on cytokine profiling, which showed that cases of erythroderma fall within distinct categories of immune activation. This categorization may have utility in guiding clinical decisions.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 3","pages":"235-243"},"PeriodicalIF":1.6,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142813377","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":"Foamy Cell Angiosarcoma Resembling a Xanthomatous Histiocytic Infiltrate Without Evidence of Vascular Malignancy","authors":"Jolee Potts,&nbsp;George J. Harocopos,&nbsp;Aaron J. Russell","doi":"10.1111/cup.14772","DOIUrl":"10.1111/cup.14772","url":null,"abstract":"<div>\u0000 \u0000 <p>Angiosarcoma is a rare and aggressive malignancy of endothelial cells with multiple subtypes. Foamy cell angiosarcoma is a rare variant in which endothelial cells demonstrate “foamy” cytoplasmic change. We present the case of a 59-year-old male who presented with progressive erythema and swelling of the midface and bilateral eyelids. Two biopsies obtained 3 months apart showed an infiltrate of foamy mononuclear cells in the deep dermis, resembling a xanthomatous histiocytic process. Clinical work-up for disorders including Erdheim-Chester disease, Langerhans cell histiocytosis, and necrobiotic xanthogranuloma was negative. Nine months later, a third set of biopsies was performed showing a similar infiltrate of foamy histiocyte-like cells within the deep dermis. However, there was also a dermal proliferation of irregular vascular spaces lined by atypical endothelial cells, diagnostic of angiosarcoma. Subsequent immunohistochemical stains demonstrated expression of CD31 and ERG within the foamy cells in both sets of biopsies, strongly suggesting endothelial lineage and supporting a diagnosis of foamy cell angiosarcoma. CD34 was negative. This case represents a very unusual presentation of angiosarcoma and a diagnostic conundrum. In cases such as these, especially when features of a vascular proliferation are absent, ERG appears to be the most useful marker for differentiating foamy cell angiosarcoma from histopathologic mimickers.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 3","pages":"189-193"},"PeriodicalIF":1.6,"publicationDate":"2024-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142791928","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":"The Roles of Vitamin D Receptor (VDR) and CD8+ T-Lymphocytes in Acral and Mucosal Melanoma Invasion Depth","authors":"Hermin Aminah Usman,&nbsp;Fitria Sholihah,&nbsp;Birgitta M. Dewayani,&nbsp;Octavianus Giovani","doi":"10.1111/cup.14771","DOIUrl":"10.1111/cup.14771","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Acral and mucosal melanomas, the most common sun-shielded site melanoma subtypes in Asia and Indonesia, often yield poor prognoses. The invasion depth reflects their progressivity, and the pathogenesis is influenced by vitamin D receptor (VDR) status and CD8+ T-Lymphocyte amount. This study aims to determine the association between the invasion depth of acral and mucosal melanomas with their VDR and CD8+ immunoexpression.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A cross-sectional observational study was conducted on 60 formalin-fixed paraffin-embedded (FPPE) samples, with equal representation in acral and mucosal melanoma groups from 2017 to 2021. The samples were assessed for the invasion depth and immunoexpression of VDR and CD8+. A chi-square test with an alternative Exact–Fisher analysis was used to determine the association between the variables in both subtype groups.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>An association between VDR and CD8+ immunoexpression and invasion depth in acral melanoma (<i>p</i> value = 0.0001 and 0.009, respectively) was observed, while only VDR immunoexpression was associated with the invasion depth in mucosal melanoma (<i>p</i>-value =0.004). Interestingly, no association was found between CD8+ immunoexpression and the invasion depth in mucosal melanoma (<i>p</i> = 0.640).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The role of VDR and CD8+ T-lymphocytes are inversely associated with melanoma depth in acral melanoma, while only VDR is associated with melanoma depth in mucosal melanoma.</p>\u0000 </section>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 3","pages":"227-234"},"PeriodicalIF":1.6,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142780244","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":"Adolescent Superficial CD34-Positive Fibroblastic Tumor With Unique IHC Profile","authors":"Scott Kuan-Wen Wang,&nbsp;Srinivas Mandavilli","doi":"10.1111/cup.14770","DOIUrl":"10.1111/cup.14770","url":null,"abstract":"<div>\u0000 \u0000 <p>Superficial CD34-positive fibroblastic tumor (SCD34FT) is a relatively uncommon soft tissue neoplasm, first identified in 2014 and included in the latest, fifth edition of the World Health Organization Soft Tissue and Bone Tumors Classification. A subset of SCD34FTs that exhibit <i>PRDM10</i> rearrangement may overlap with other <i>PRDM10</i>-rearranged soft tissue tumors, suggesting a shared pathogenic pathway. We report a case of a 16-year-old patient, one of the youngest diagnosed, with an SCD34FT on the forearm, featuring both <i>PRDM10</i> rearrangement and a unique, diffuse expression of cytokeratin (CK AE1/AE3). This case contributes to the expanding literature on SCD34FT, highlighting its clinical and pathological diversity.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 3","pages":"185-188"},"PeriodicalIF":1.6,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142785919","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":"Atypical Type 2 Lepra Reaction Masquerading as Recurrent Sweet Syndrome","authors":"Seraphima Sidhom,&nbsp;Eric Yang,&nbsp;Asha Gowda,&nbsp;Lori S. Kim,&nbsp;Leslie Robinson-Bostom,&nbsp;Cathy Massoud","doi":"10.1111/cup.14762","DOIUrl":"10.1111/cup.14762","url":null,"abstract":"<div>\u0000 \u0000 <p>Erythema nodosum leprosum (ENL) is an immune complex-mediated response in <i>Mycobacterium leprae</i> infection, presenting with fever, arthralgias, and tender cutaneous lesions. It mimics Sweet syndrome (SS) clinically and histologically but requires distinct management. A 65-year-old man with recent travel presented with fever and edematous plaques. Initial findings supported SS, improving with corticosteroids. Symptom recurrence and a contact's leprosy diagnosis led to further testing, revealing M. <i>leprae</i> through repeat staining and tissue PCR. This case underscores the need to consider ENL in Sweet-like cases with relevant travel history. Repeat staining and molecular testing are essential for accurate diagnosis and treatment.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 3","pages":"180-184"},"PeriodicalIF":1.6,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142780239","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":"An Unusual, Symmetric Rash on Both Forearms in a 94-Year-Old Patient A Clinicopathological Challenge and Diagnostic Pitfall","authors":"Anna-Maria Forster,&nbsp;Beda Muehleisen","doi":"10.1111/cup.14764","DOIUrl":"10.1111/cup.14764","url":null,"abstract":"<div>\u0000 \u0000 <p>\u0000 <i>Trichophyton rubrum</i> (<i>T. rubrum</i>), an anthropophilic ectothrix dermatophyte usually causes minor skin infection confined to the stratum corneum of the epidermis, to nails and the hair in immunocompetent persons. Life-threatening invasive dermatophyte infections are rare and mainly reported in immunosuppressed patients such as organ transplant recipients. We herein present an extraordinary case of a symmetric bilateral invasive <i>T. rubrum</i> infection on both forearms in a 94-year-old male patient, histomorphologically mimicking cutaneous blastomycosis. Invasive <i>T. rubrum</i> with atypical large round spore-like organisms resembling <i>Blastomyces dermatitidis (B. dermatitidis</i>) is common diagnostic pitfall but has never been reported in the setting of a concomitant systemic anti PD-1 checkpoint-inhibitor treatment. Correct diagnosis of atypical Blastomyces-like <i>T. rubrum</i> based on morphology and staining characteristics alone can be challenging and emphasizes the need for confirmation via culture or PCR-testing.</p>\u0000 </div>","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 2","pages":"73-77"},"PeriodicalIF":1.6,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142780238","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":"Diagnostic Accuracy of Treponema pallidum Immunostaining in a Cohort of Patients With Secondary Syphilis","authors":"Luis J. Borda,&nbsp;Ryan C. Saal,&nbsp;Robert J. Pariser","doi":"10.1111/cup.14760","DOIUrl":"10.1111/cup.14760","url":null,"abstract":"&lt;p&gt;Immunohistochemical (IHC) staining/Immunohistochemistry (IHC) for spirochetes in skin specimens can be used to diagnose secondary syphilis. In the last decade, IHC has replaced silver staining as the primary histochemical diagnostic tool, given its greater sensitivity and specificity [&lt;span&gt;1&lt;/span&gt;]. Traditionally, nontreponemal serologic testing, such as the rapid plasma reagin (RPR) test, has served as the primary screening method for diagnosing syphilis, despite its somewhat limited specificity [&lt;span&gt;2&lt;/span&gt;]. Limited data are available assessing IHC's diagnostic accuracy compared to standard serologic testing. Our objective is to determine the diagnostic accuracy of IHC in comparison to RPR serology.&lt;/p&gt;&lt;p&gt;In our study, we identified 175 patients in a private practice whose skin eruption generated a differential diagnosis including secondary syphilis, and who also underwent skin biopsies with additional anti-&lt;i&gt;Treponema pallidum&lt;/i&gt; IHC from January 1, 2014 to December 31, 2022. The anti-&lt;i&gt;T. pallidum&lt;/i&gt; IHC (Biocare Medical, no dilution [ready to use], Ref APA135AA, Pacheco, CA, USA) was assessed by two independent reviewers ensuring inter-rater reliability (Figure 1). Those patients who did not have a contemporaneous (RPR) test or underwent anti-&lt;i&gt;T. pallidum&lt;/i&gt; immunostaining for other diseases were excluded (Figure 2). We determined the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of anti-&lt;i&gt;T. pallidum&lt;/i&gt; IHC in this cohort.&lt;/p&gt;&lt;p&gt;The enrolled cohort consisted of 26 patients, of whom 17 (65%) were male with an average age of 42.54 ± 13.39 years (SD). All of these skin biopsies were analyzed as pre-treatment samples, with the exception of one patient. In comparison to RPR serology, anti-&lt;i&gt;T. pallidum&lt;/i&gt; IHC showed sensitivity of 80.00%, specificity of 90.48%, PPV of 66.67%, and NPV of 95.00%.&lt;/p&gt;&lt;p&gt;Our findings support IHC as a potentially valid method for diagnosing syphilis when compared to nontreponemal serologic testing. Previous studies have shown similar results, with a range of documented sensitivities of 60%–94% for anti-&lt;i&gt;T. pallidum&lt;/i&gt; immunostaining [&lt;span&gt;1, 3-5&lt;/span&gt;]. Reasons for the variations in prior sensitivities include the sample size of our cohort, exclusion of specimen without an associated RPR test and our sample only consisting of lesions of secondary syphilis. In our study, one patient who had a positive RPR and negative IHC result had been recently treated for syphilis and developed a “new” skin eruption which was determined to be a Jarisch–Herxheimer reaction. It would be expected that the spirochetes in his skin would disappear before the serologic response normalized. Occasional false positives for IHC have been seen in borreliosis and other spirochete infections but were not observed in our study [&lt;span&gt;6, 7&lt;/span&gt;].&lt;/p&gt;&lt;p&gt;The Centers for Disease Control and Prevention does not currently recognize IHC as a diagnostic method for syphilis despit","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 5","pages":"333-335"},"PeriodicalIF":1.6,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cup.14760","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142780242","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":"Diffuse PRAME Expression in Transdifferentiated Melanomas","authors":"Shaymaa Hegazy,&nbsp;Arivarasan Karunamurthy,&nbsp;Ivy John","doi":"10.1111/cup.14769","DOIUrl":"10.1111/cup.14769","url":null,"abstract":"&lt;p&gt;Dedifferentiated melanoma is defined by the absence of typical histopathologic and immunophenotypic features associated with melanoma. Much like dedifferentiated liposarcomas and malignant peripheral nerve sheath tumors, dedifferentiated melanomas exhibit a propensity for heterologous transdifferentiation, showcasing a spectrum of phenotypes including rhabdomyosarcomatous-like, fibroblastic/myofibroblastic-like, adenocarcinoma-like, leiomyosarcoma-like, schwannian and perineural-like, teratocarcinosarcoma-like, and chondrosarcomatous-like [&lt;span&gt;1, 2&lt;/span&gt;]. Accurate diagnosis of dedifferentiated melanoma demands a high level of suspicion and comprehensive sampling to identify either a conventional melanoma precursor or mutations consistent with melanoma, such as &lt;i&gt;BRAF, NRAS, or NF1&lt;/i&gt; [&lt;span&gt;1, 3&lt;/span&gt;]. In recent years, immunohistochemistry focusing on PRAME (preferentially expressed in melanoma) has emerged as a valuable diagnostic tool for melanocytic tumors. The vast majority of primary and metastatic cutaneous melanomas express PRAME, though exceptions may arise, particularly in desmoplastic melanomas [&lt;span&gt;4&lt;/span&gt;]. Rare, isolated case reports and a recent single study have reported strong and diffuse PRAME expression in dedifferentiated melanomas; however, its expression in transdifferentiated melanomas remains underexplored [&lt;span&gt;5-8&lt;/span&gt;]. Herein, we present the findings of PRAME expression in three cases of transdifferentiated melanomas.&lt;/p&gt;&lt;p&gt;Received in consultation is a 15-cm groin mass with an outside diagnosis of high-grade malignant neoplasm with chondrosarcomatous differentiation with a suggested differential diagnosis of dedifferentiated chondrosarcoma and chondroblastic osteosarcoma. The submitted sections showed morphological features reminiscent of dedifferentiated chondrosarcoma with an abrupt transition between conventional hyaline cartilage and malignant sarcomatoid neoplasm (Figure 1a). Further history revealed the patient's documented &lt;i&gt;BRAF V600E&lt;/i&gt; mutated malignant melanoma originating from the left thigh, with biopsy-proven lymph node metastasis to the neck. Although conventional melanocytic markers were negative in the current specimen, immunohistochemical staining for PRAME revealed diffuse and strong nuclear expression in the sarcomatoid component (Figure 1b). Additionally, BRAF immunohistochemistry confirmed positivity in the tumor cells (Figure 1c). Molecular studies were performed comparing the current specimen (left groin mass) and metastatic melanoma to the neck and showed identical mutations involving &lt;i&gt;BRAF, TERT, and TP53&lt;/i&gt; in both components, confirming that both tumors are clonally related. Therefore, a diagnosis of dedifferentiated melanoma with chondrosarcomatous differentiation was rendered.&lt;/p&gt;&lt;p&gt;As part of ongoing patient care, histologic slides from a cutaneous rhabdomyosarcoma involving the forearm were received for review. Histopathologic examination showed a well-circumscribed","PeriodicalId":15407,"journal":{"name":"Journal of Cutaneous Pathology","volume":"52 4","pages":"269-271"},"PeriodicalIF":1.6,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/cup.14769","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142769411","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}