Applied Immunohistochemistry & Molecular Morphology最新文献

{"title":"Merkel Cell Carcinoma With Extensive Bone Marrow Metastasis and Peripheral Blood Involvement: A Case Report With Immunohistochemical and Mutational Studies.","authors":"Benjamin Highland, William Patrick Morrow, Karen Arispe, Michael Beaty, Danielle Maracaja","doi":"10.1097/PAI.0000000000001214","DOIUrl":"10.1097/PAI.0000000000001214","url":null,"abstract":"<p><p>Merkel cell carcinoma (MCC) is a rare, highly aggressive skin cancer of neuroendocrine origin that is typically associated with either the presence of Merkel cell polyomavirus or chronic exposure to ultraviolet (UV) light. We report a case of relapsed MCC that presented with new symptoms of fatigue, back pain, and myeloid left shift identified during scheduled follow-up. The patient was found to have circulating neoplastic cells in the peripheral blood and bone marrow metastasis. Immunohistochemistry for synaptophysin, CD56, INSM-1, CK20, CD117 were positive, whereas CD34, TdT, Chromogranin, CD10, myeloperoxidase, CD3 and CD19 were negative. Flow cytometry of the peripheral blood confirmed the presence of an abnormal nonhematopoietic cell population expressing CD56 positivity. A next-generation sequencing (NGS) panel revealed the presence of variants in RB1, TP53, and other genes, some of which have not been previously described in MCC. This rare presentation highlights the challenges in the diagnosis and management of MCC.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141591814","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":"Utility of PD-1, PD-L1, and IDO-1 Stains in Ocular Extranodal Marginal Zone Lymphoma (MZL) and Diffuse Large B-cell Lymphoma (DLBCL).","authors":"Alexander Craig, Ekin Güney, Melike Pekmezci, Michele Bloomer, Zoltan Laszik, Robert S Ohgami, Angus Toland, Hannes Vogel, Taylor Forns, Endi Wang, James Rubenstein, Kwun Wah Wen","doi":"10.1097/PAI.0000000000001207","DOIUrl":"10.1097/PAI.0000000000001207","url":null,"abstract":"<p><p>Extranodal marginal zone lymphoma (EMZL) is the most common subtype of ocular lymphomas. Diffuse large B-cell lymphoma (DLBCL) and EMZL with large-cell transformation present diagnostic challenges. Radiotherapy is the standard treatment for ocular lymphomas, but complications and relapse are common. Diagnostic utility in challenging cases, as well as treatment options using immune checkpoint inhibitors, are unclear in ocular lymphomas. We herein investigated the PD-1, PD-L1, and IDO1 staining patterns in 20 cases of ocular lymphomas, including EMZL (n=14), EMZL with increased large cells (n=2), and DLBCL (n=4). PD-1, PD-L1, and IDO1 staining was not detected in lymphoma cells in any cases but was observed within the tumor microenvironment in all cases. Positivity for PD-1, PD-L1, and IDO1 in inflammatory cells was seen either intratumorally or peritumorally. In all 6 cases with significantly more large B cells, the density of PD-1, PD-L1, and IDO1 expression in the tumor microenvironment was higher than that of the remaining 14 cases without large B cells ( P -value<0.0001), whereas other clinicopathologic features showed no statistical correlation. Increased expression of PD-1, PD-L1, and IDO1 in the inflammatory milieu in cases with large cells may provide diagnostic utility in small biopsies as well as therapeutic potential.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141428045","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":"Utility of SATB2 and MOC-31 Immunostains to Distinguish Between Poorly Differentiated Rectal Adenocarcinoma and Anal Squamous Cell Carcinoma.","authors":"Jiayun M Fang, Naziheh Assarzadegan, Jerome Cheng, Laura Lamps","doi":"10.1097/PAI.0000000000001218","DOIUrl":"10.1097/PAI.0000000000001218","url":null,"abstract":"<p><strong>Objectives: </strong>Colorectal adenocarcinoma and squamous cell carcinoma (SCC) can arise in the anorectum and present a significant diagnostic challenge when poorly differentiated. Accurate diagnosis can significantly influence management, as the treatments for these conditions involve distinct neoadjuvant chemoradiotherapy regimens. MOC-31 and SATB2 have been utilized as specific markers of glandular differentiation and colorectal origin, respectively, but studies have shown that they may be positive in squamous cell carcinoma of other sites. This raises the concern that MOC-31 and SATB2 may be positive in squamous cell carcinoma of the anorectum, and overreliance on these stains may be a potential diagnostic pitfall in differentiating rectal poorly differentiated adenocarcinoma (PDA) from anal nonkeratinizing SCC.</p><p><strong>Methods: </strong>We identified biopsies from 10 rectal PDA and 17 anorectal nonkeratinizing SCC cases and stained them for MOC-31 and SATB2.</p><p><strong>Results: </strong>We found that MOC-31 was highly sensitive, being positive in 10/10 cases of rectal PDA, but not specific, as it was also positive in 11/17 SCC cases. In contrast, SATB2 was both sensitive, with positive staining in 10/10 rectal PDA cases, and specific, with negative staining in 17/17 SCC cases. This includes equivocal staining in 4 of these negative SCC cases. MOC-31 had a sensitivity of 100% and specificity of 35.3%, while SATB2 had a sensitivity of 100% and specificity of 100%.</p><p><strong>Conclusions: </strong>Unlike squamous mucosa of the head and neck, and esophagus, SCC of the anus does not frequently stain positively for SATB2. These data suggest that SATB2 is a reliable marker in distinguishing rectal PDA from anorectal nonkeratinizing SCC, whereas MOC-31 is commonly positive in SCC of the anus. It is also important to note that equivocal SATB2 staining may be seen in SCC.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141989283","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":"Peripheral Blood and Bone Marrow Findings in Treatment-Naive Patients With Cytopenia(s)/Myeloid Neoplasms Harboring Both a Germline and a Somatic DDX41 Mutation.","authors":"Frido K Bruehl, Ismail Elbaz Younes, David S Bosler, Katalin Kelemen, Liuyan Jiang, Kaaren K Reichard","doi":"10.1097/PAI.0000000000001215","DOIUrl":"10.1097/PAI.0000000000001215","url":null,"abstract":"<p><p>DDX41 -associated cytopenia(s)/myeloid neoplasms ( DDX41 -C/MNs) are an emerging pathologic entity. We examined the hematopathologic findings in DDX41 -C/MNs with both a germline and somatic DDX41 mutation ( DDX41 -C/MNs-GS). We reviewed the peripheral blood and bone marrow (BM) findings from treatment-naive patients with DDX41 -C/MNs-GS. Thirty cases were identified: 10% (3/30) were classified as clonal cytopenia(s) of unknown significance (CCUS), 17% (5/30) as myelodysplastic neoplasm/syndrome (MDS) with <5% blasts, 20% (6/30) as MDS with 5% to 9% blasts, 20% (6/30) as MDS with 10% to 19% blasts, and 33% (10/30) as acute myeloid leukemia (AML). All patients were cytopenic; circulating blasts were rare (23%, 7/30). 63% (19/30) showed dysmegakaryopoiesis. Dyserythropoiesis and dysgranulopoiesis were uncommon; seen in 20% (6/30) and 7% (2/30), respectively. Sixty-six percent (19/29) of cases were normocellular; 43% (13/30) showed erythroid predominance. Flow cytometry revealed an unremarkable blast myeloid phenotype. Blasts were intermediate sized with round nuclei, distinct nucleoli, and light blue cytoplasm with azurophilic granules. The karyotype was predominantly normal (93%, 26/28). All germline mutations were deleterious: 53% (16/30) truncating and 47% (14/30) missense. The most common somatic variant was the R525H mutation in 70% (21/30). The BM diagnostic spectrum in DDX41- C/MNs that harbor both a germline and somatic DDX41 mutation is broad-ranging from CCUS to AML. We describe consistent hematopathologic findings that pathologists may expect in these cases.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141753176","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":"Use of SATB2 and CDX2 Immunohistochemistry to Characterize and Diagnose Colorectal Cancer.","authors":"Shunsuke Kato, Akira Koshino, Jerzy Lasota, Masayuki Komura, Chengbo Wang, Masahide Ebi, Naotaka Ogasawara, Kazuhisa Kojima, Toyonori Tsuzuki, Kenji Kasai, Satoru Takahashi, Markku Miettinen, Kunio Kasugai, Shingo Inaguma","doi":"10.1097/PAI.0000000000001216","DOIUrl":"10.1097/PAI.0000000000001216","url":null,"abstract":"<p><p>SATB2 has been reported to be highly specific for lower gastrointestinal tract tumors. On the basis of its ileum-colon conversion effects, which involve the activation of colonic genes in cooperation with CDX2 and HNF4A, we hypothesized that SATB2 and CDX2 might define the characteristics of colorectal cancers (CRCs). In the present study, the clinicopathologic and immunohistochemical characteristics of 269 CRCs were analyzed according to SATB2 and CDX2 expression. CRCs with SATB2- and/or CDX2- phenotypes showed associations with poorly differentiated histotypes ( P <0.00001), mucus production ( P =0.0019), and mismatch repair-deficient phenotypes ( P <0.00001). SATB2-/CDX2- CRCs were significantly associated with CK20-negativity, with or without CK7 expression ( P <0.00001), as well as with MUC5AC-positivity ( P <0.00001), and CD10-negativity ( P =0.00047). Negativity for SATB2 or CDX2 was associated with the expression of PD-L1 in both all CRC ( P <0.00001) and mismatch repair-proficient CRC ( P =0.000091). Multivariate Cox hazard regression analysis identified negativity for SATB2 and/or CDX2 as potential independent risk factors for patients with CRC. Regarding the diagnostic utility of SATB2, all of the 44 CRC metastases could be diagnosed as colorectal in origin if the immunohistochemical phenotypes (including CK7, CK20, and p53) of the primary lesions and patient history were considered. Among the other 684 tumors, we were unable to distinguish a case of CK7-/CK20+/CDX2+/SATB2+ ovarian mucinous cystadenocarcinoma from metastatic CRC without the patient history and clinical information.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141793872","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":"Brightfield Multiplex Immunohistochemistry Assay for PD-L1 Evaluation in Challenging Melanoma Samples.","authors":"Filippo Ugolini, Luca Tinunin, Filippo Nozzoli, Sara Simi, Dario Di Gangi, Gianna Baroni, Pietro Antonini, Anna Szumera-Ciećkiewicz, Daniela Massi","doi":"10.1097/PAI.0000000000001219","DOIUrl":"10.1097/PAI.0000000000001219","url":null,"abstract":"<p><p>Targeting the PD1/PD-L1 immune checkpoint pathway has rapidly become a therapeutic strategy for melanoma patients. Indeed, the quantification of PD-L1 expression by immunohistochemistry (IHC) in melanoma samples is already required, in some contexts, to allow access to anti-PD-1/PD-L1 immunotherapy. Despite a rising demand for PD-L1 testing, paralleling increasing cumulative experience in its assessment and quantification, it is fair to recognize that PD-L1 evaluation in melanoma samples still presents some critical issues. The aim of this technical report is to develop and validate a multiplex double staining protocol for PD-L1/SOX10 in Ventana Benchmark Ultra for routine practice. Our results show that double labeling provides the necessary tools to identify PD-L1 + melanoma cells clearly. The simultaneous visualization of 2 different proteins targets allows the topographical relationship between the 2 labeling to be evaluated within the context of the tissue morphology. Future studies are needed to test this technique's real-world applicability and effectiveness in implementing interpathologist agreement.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11371108/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142019210","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":"Universal Lynch Syndrome Screening in Colorectal Cancer: A 5-Year Experience of a Portuguese Pathology Department.","authors":"Vânia Almeida, Luis Veloso, Paulo Teixeira, Augusta Cipriano","doi":"10.1097/PAI.0000000000001212","DOIUrl":"https://doi.org/10.1097/PAI.0000000000001212","url":null,"abstract":"<p><p>Lynch syndrome (LS) is a prevalent genetic condition associated with colorectal cancer (CRC). Accurate identification of LS patients is challenging, and a universal tumor screening approach has been recommended. We present the methodology and results of universal LS screening in our hospital's Pathology Department. This retrospective study analyzed CRC tumors from a 5-year period (2017-2021). Immunohistochemistry was used to assess MMR protein expression, followed by BRAF V600E analysis and MLH1 promoter methylation. Statistical analysis examined associations between clinicopathologic variables MMR status and LS-suspected tumors. The study analyzed 939 colorectal carcinomas, with 8.7% exhibiting mismatch repair (MMR) deficiency, significantly lower than previous research. After applying the algorithm, 24 LS-suspected cases were identified, accounting for 2.6% of tested patients and 29.3% of MMR-deficient tumors. Our study establishes the feasibility of universal testing for all new cases of CRC in detecting individuals at risk for LS, even in the absence of clinical information. To gain a comprehensive understanding of the MMR status in our population, further investigations are warranted.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141894702","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":"Expression and Clinical Significance of Ki-67, CD10, BCL6, MUM1, c-MYC, and EBV in Diffuse Large B Cell Lymphoma Patients.","authors":"Alireza Sadeghipour, Seyed Reza Taha, Mahdieh Shariat Zadeh, Farid Kosari, Pegah Babaheidarian, Fahimeh Fattahi, Navid Abdi, Fatemeh Tajik","doi":"10.1097/PAI.0000000000001208","DOIUrl":"10.1097/PAI.0000000000001208","url":null,"abstract":"<p><strong>Introduction: </strong>Diffuse large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL) in adults. Although studies regarding the association between the expression of Ki-67, CD10, BCL6, and MUM1 proteins, as well as c-MYC amplification and EBV status with clinicopathologic characteristics have rapidly progressed, their co-expression and prognostic role remain unsatisfactory. Therefore, this study aimed to investigate the association between the expression of all markers and clinicopathologic features and their prognostic value in DLBCL. Also, the co-expression of markers was investigated.</p><p><strong>Methods: </strong>The protein expression levels and prognostic significance of Ki-67, CD10, BCL6, and MUM1 were investigated with clinical follow-up in a total of 53 DLBCL specimens (including germinal center B [GCB] and activated B cell [ABC] subtypes) as well as adjacent normal samples using immunohistochemistry (IHC). Besides, the clinical significance and prognostic value of c-MYC and EBV status were also evaluated through chromogenic in situ hybridization (CISH), and their correlation with other markers was also assessed.</p><p><strong>Results: </strong>The results demonstrated a positive correlation between CD10 and BCL6 expression, with both markers being associated with the GCB subtype ( P< 0.001 and P =0.001, respectively). Besides, we observe a statistically significant association between MUM1 protein expression and clinicopathologic type ( P< 0.005) as well as a positive association between c-MYC and recurrence ( P =0.028). Our survival analysis showed that patients who had responded to R-CHOP treatment had better overall survival (OS) and progression-free survival (PFS) than those who did not.</p><p><strong>Conclusion: </strong>Collectively, this study's results add these markers' value to the existing clinical understanding of DLBCL. However, further investigations are needed to explore markers' prognostic and biological roles in DLBCL patients.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141318694","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 BRAF V600E Mutation and Clinicopathological Changes Among Patients With Hashimoto Thyroiditis, Papillary Thyroid Carcinoma With Hashimoto Thyroiditis, and Nodular Goiter.","authors":"Juqing Deng, Lu Yu, Shibi Luo, Zhongcun Yang, Jie Liu, Liqiong Liao","doi":"10.1097/PAI.0000000000001204","DOIUrl":"10.1097/PAI.0000000000001204","url":null,"abstract":"<p><p>The study aimed to investigate the BRAF V600E mutation and clinicopathological changes among patients with Hashimoto thyroiditis (HT), papillary thyroid carcinoma (PTC) with Hashimoto thyroiditis (HT), or nodular goiter (NG). A total of 87 patients with the BRAF V600E mutation who were diagnosed with HT (including with hyperplasia dysplasia), PTC with HT, and PTC with NG were enrolled. Clinical data, concentrations of antithyroglobulin antibodies (TGAb) and thyroid microsomal antibodies (TMAb) in the serum thyroid-function levels, and the result presence of the BRAF V600E mutation were retrospectively analyzed. There were significant differences in the BRAF V600E mutation rates between the HT and PTC with HT groups ( P <0.05) and the HT and PTC with NG groups ( P <0.05), whereas no significant difference was found between the PTC with HT and PTC with NG groups. There was no difference in incidences of PTC between HT with elevated TGAb and TMAb group and those with baseline levels. The incidence of multifocal PTC was higher in the PTC with HT group; however, the difference was not significant. Our findings documented that BRAF mutation distinguished between the benign HT and the malignant PTC groups. The serum levels of TGAb and TMAb autoantibodies did not directly correlate with PTC in the background of HT. HT and NG may similarly contribute to the pathogenesis of PTC.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11296278/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141077029","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":"Unusual PEComa With PRCC :: TFE3 Fusion Mimicking Sinonasal Tract Melanoma.","authors":"Jerzy Lasota, Lester D R Thompson, Małgorzata Chłopek, Artur Kowalik, Markku Miettinen","doi":"10.1097/PAI.0000000000001211","DOIUrl":"10.1097/PAI.0000000000001211","url":null,"abstract":"<p><strong>Background: </strong>We report a nasal cavity unusual perivascular epithelioid cell tumor (PEComa) mimicking mucosal melanoma.</p><p><strong>Methods: </strong>Immunohistochemistry was performed using BenchMark Ultra and panel of antibodies. The Ion Torrent platform and Ion AmpliSeq cancer hotspot panel were utilized for DNA genotyping. Target-specific RNA libraries for the detection of fusion transcripts were constructed using Archer Universal RNA Reagent Kit v2 and Archer FusionPlex Solid Tumor panel and sequenced on the MiSeqDx instrument.</p><p><strong>Results: </strong>The tumor, diagnosed in 46-year-old female, was composed of spindle cells, and lacked pigmentation. Immunohistochemically, it showed a patchy HMB-45 positivity. Other melanocytic markers (S100 protein, Melan-A, SOX10) were negative. The tumor cells were weakly positive for KIT (CD117) while negative for smooth muscle actin, pancytokeratin cocktail (AE1/AE3), and synaptophysin. Diagnosis of primary sinonasal tract mucosal melanoma was favored. Additional molecular studies detected PRCC :: TFE3 fusion as the sole genetic change, and suggested the diagnosis of unusual PEComa. Previously, TFE3 fusions were reported in a subset of PEComas but not in melanomas, while PRCC involvement has only been documented once in an ocular PEComa. Immunohistochemistry revealed strong nuclear TFE3 expression concordant with the molecular findings.</p><p><strong>Conclusions: </strong>This report emphasis the importance of molecular testing in the differential diagnosis between PEComa and melanoma, especially when the tumor arises in a site typical of melanoma but showing an unusual morphology and immunophenotype. The detection of TFE3 fusion transcripts suggested the diagnosis of SNT PEComa, although it cannot be excluded that this and similar tumors represent a distinct diagnostic category.</p>","PeriodicalId":48952,"journal":{"name":"Applied Immunohistochemistry & Molecular Morphology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141555788","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}