{"title":"Mast Cell Sarcoma of the Small Intestine Diagnosed by Ascitic Fluid Cytology: A Case Report with Molecular and Immunophenotypic Correlation.","authors":"Kai Mizoguchi, Kentaro Tsuji, Yuki Teramoto, Shinya Otsuki, Masakazu Fujimoto, Mizuki Watanabe, Seigi Oshima, Tomoshige Shimizu, Noriyoshi Yoshinaga, Hiroaki Ito, Ayako Furuhata, Masahiro Hirata, Hironori Haga","doi":"10.1159/000547483","DOIUrl":null,"url":null,"abstract":"<p><strong>Introduction: </strong>Mast cell sarcoma (MCS) is a rare and aggressive neoplasm with limited cytologic description, particularly in effusion specimens.</p><p><strong>Case presentation: </strong>A 55-year-old man presented with a small intestinal tumor and peritoneal dissemination. Ascitic fluid cytology revealed numerous large atypical cells with round to horseshoe-shaped nuclei and abundant cytoplasm containing metachromatic granules. Some cells displayed hand mirror-like morphology. Immunocytochemistry showed CD117 and tryptase positivity, and a KIT D816Y mutation was identified. The diagnosis of MCS was later confirmed by biopsy.</p><p><strong>Conclusion: </strong>This is the first reported case of MCS diagnosed by effusion cytology. Recognition of hand mirror-like morphology and metachromatic granules, combined with immunocytochemistry and molecular analysis, may support early diagnosis.</p>","PeriodicalId":6959,"journal":{"name":"Acta Cytologica","volume":" ","pages":"1-6"},"PeriodicalIF":1.7000,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Cytologica","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1159/000547483","RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"PATHOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Introduction: Mast cell sarcoma (MCS) is a rare and aggressive neoplasm with limited cytologic description, particularly in effusion specimens.
Case presentation: A 55-year-old man presented with a small intestinal tumor and peritoneal dissemination. Ascitic fluid cytology revealed numerous large atypical cells with round to horseshoe-shaped nuclei and abundant cytoplasm containing metachromatic granules. Some cells displayed hand mirror-like morphology. Immunocytochemistry showed CD117 and tryptase positivity, and a KIT D816Y mutation was identified. The diagnosis of MCS was later confirmed by biopsy.
Conclusion: This is the first reported case of MCS diagnosed by effusion cytology. Recognition of hand mirror-like morphology and metachromatic granules, combined with immunocytochemistry and molecular analysis, may support early diagnosis.
期刊介绍：
With articles offering an excellent balance between clinical cytology and cytopathology, ''Acta Cytologica'' fosters the understanding of the pathogenetic mechanisms behind cytomorphology and thus facilitates the translation of frontline research into clinical practice. As the official journal of the International Academy of Cytology and affiliated to over 50 national cytology societies around the world, ''Acta Cytologica'' evaluates new and existing diagnostic applications of scientific advances as well as their clinical correlations. Original papers, review articles, meta-analyses, novel insights from clinical practice, and letters to the editor cover topics from diagnostic cytopathology, gynecologic and non-gynecologic cytopathology to fine needle aspiration, molecular techniques and their diagnostic applications. As the perfect reference for practical use, ''Acta Cytologica'' addresses a multidisciplinary audience practicing clinical cytopathology, cell biology, oncology, interventional radiology, otorhinolaryngology, gastroenterology, urology, pulmonology and preventive medicine.
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