{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T15:09:12Z","timestamp":1773673752481,"version":"3.50.1"},"reference-count":16,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T00:00:00Z","timestamp":1773619200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Diagnostics"],"abstract":"<jats:p>Background and Clinical Significance: Plexiform fibromyxoma (PFM) is a rare benign gastric mesenchymal neoplasm characterized by multinodular plexiform growth of bland spindle cells in a myxoid or fibromyxoid stroma. We report a case of the cellular form of PFM with limited myxoid stroma and aberrant KIT expression, resulting in diagnostic difficulty by biopsy. Case Presentation: A 59-year-old woman presented with a slowly enlarging 15 mm gastric antral submucosal tumor. A resected specimen by laparoscopic and endoscopic cooperative surgery revealed spindle cell proliferation forming plexiform nodules with a myxoid background in limited areas. Positive immunoreactivity of a subset of spindle cells for KIT suggested a diagnosis of gastrointestinal stromal tumor (GIST), although DOG1 was negative. In addition, diffuse staining for CD10, smooth muscle actin, and D2-40 was confusing. MALAT1::GLI1 fusion was detected by next-generation sequencing analysis. Consequently, a diagnosis of PFM was established. Conclusions: This case expands the morphologic and immunophenotypic spectrum of PFM and indicates the possible diagnostic utility and biological significance of D2-40 expression. Although molecular confirmation of MALAT1::GLI1 fusion is definitive for the diagnosis of PFM, the findings of the present case may aid diagnosis in challenging cases that mimic GIST.<\/jats:p>","DOI":"10.3390\/diagnostics16060879","type":"journal-article","created":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T13:32:07Z","timestamp":1773667927000},"page":"879","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Plexiform Fibromyxoma with MALAT1\u2013GLI1 Fusion with Limited Myxoid Stroma, Aberrant KIT Expression, and Diffuse D2-40 Expression: A Case Report"],"prefix":"10.3390","volume":"16","author":[{"given":"Kotaro","family":"Watanabe","sequence":"first","affiliation":[{"name":"Department of Diagnostic Pathology, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kazuhito","family":"Tanaka","sequence":"additional","affiliation":[{"name":"Department of Diagnostic Pathology, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kohei","family":"Ohkura","sequence":"additional","affiliation":[{"name":"Department of Diagnostic Pathology, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kojiro","family":"Eto","sequence":"additional","affiliation":[{"name":"Department of Gastroenterological Surgery, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Satoshi","family":"Ida","sequence":"additional","affiliation":[{"name":"Department of Gastroenterological Surgery, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kohei","family":"Yamashita","sequence":"additional","affiliation":[{"name":"Department of Gastroenterological Surgery, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yushi","family":"Kawakami","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology and Hepatology, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1553-2598","authenticated-orcid":false,"given":"Keita","family":"Kai","sequence":"additional","affiliation":[{"name":"Department of Diagnostic Pathology, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hidetaka","family":"Yamamoto","sequence":"additional","affiliation":[{"name":"Department of Pathology, Graduate School of Medicine, Dentistry & Pharmaceutical Science, Okayama University, Okayama 700-8558, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2473-6966","authenticated-orcid":false,"given":"Yasuhito","family":"Tanaka","sequence":"additional","affiliation":[{"name":"Department of Gastroenterology and Hepatology, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0886-4618","authenticated-orcid":false,"given":"Masaaki","family":"Iwatsuki","sequence":"additional","affiliation":[{"name":"Department of Gastroenterological Surgery, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yoshiki","family":"Mikami","sequence":"additional","affiliation":[{"name":"Department of Diagnostic Pathology, Kumamoto University Hospital, Kumamoto 860-8556, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"724","DOI":"10.1097\/01.pas.0000213448.54643.2f","article-title":"Plexiform angiomyxoid myofibroblastic tumor of the stomach","volume":"31","author":"Takahashi","year":"2007","journal-title":"Am. J. Surg. Pathol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1624","DOI":"10.1097\/PAS.0b013e3181ae666a","article-title":"Plexiform fibromyxoma: A distinctive benign gastric antral neoplasm not to be confused with a myxoid GIST","volume":"33","author":"Miettinen","year":"2009","journal-title":"Am. J. Surg. Pathol."},{"key":"ref_3","unstructured":"Bosman, F.T., Carneiro, F., Hruban, R., and Teise, N.D. (2010). Mesenchymal tumors of the stomach. WHO Classification of Tumours of the Digestive System, IARC. [4th ed.]."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"409","DOI":"10.4251\/wjgo.v13.i5.409","article-title":"Plexiform fibromyxoma: Review of rare mesenchymal gastric neoplasm and its differential diagnosis","volume":"13","author":"Arslan","year":"2021","journal-title":"World J. Gastrointest. Oncol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"e298","DOI":"10.5858\/arpa.2024-0254-RA","article-title":"Plexiform Fibromyxoma: A Review and Discussion of the Differential Diagnosis of Gastrointestinal Mesenchymal Tumors","volume":"149","author":"Szczepanski","year":"2025","journal-title":"Arch. Pathol. Lab. Med."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"335","DOI":"10.1002\/path.4730","article-title":"Recurrent MALAT1-GLI1 oncogenic fusion and GLI1 up-regulation define a subset of plexiform fibromyxoma","volume":"239","author":"Spans","year":"2016","journal-title":"J. Pathol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1401","DOI":"10.1097\/PAS.0b013e3181a90e1a","article-title":"DOG1 antibody in the differential diagnosis of gastrointestinal stromal tumors: A study of 1840 cases","volume":"33","author":"Miettinen","year":"2009","journal-title":"Am. J. Surg. Pathol."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Wu, C.-E., Tzen, C.-Y., Wang, S.-Y., and Yeh, C.-N. (2019). Clinical Diagnosis of Gastrointestinal Stromal Tumor (GIST): From the Molecular Genetic Point of View. Cancers, 11.","DOI":"10.3390\/cancers11050679"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1097\/PAS.0000000000001010","article-title":"A distinct malignant epithelioid neoplasm with GLI1 gene rearrangements, frequent S100 protein expression, and metastatic potential: Expanding the spectrum of pathologic entities with ACTB\/MALAT1\/PTCH1-GLI1 fusions","volume":"42","author":"Antonescu","year":"2018","journal-title":"Am. J. Surg. Pathol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"553","DOI":"10.1177\/1066896919900548","article-title":"A malignant neoplasm from the jejunum with a MALAT1-GLI1 fusion and 26-year survival history","volume":"28","author":"Prall","year":"2020","journal-title":"Int. J. Surg. Pathol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"246","DOI":"10.1186\/s12967-019-1995-z","article-title":"Loss of the PTCH1 tumor suppressor defines a new subset of plexiform fibromyxoma","volume":"17","author":"Banerjee","year":"2019","journal-title":"J. Transl. Med."},{"key":"ref_12","first-page":"10926","article-title":"Plexiform fibromyxoma of the stomach: A clinicopathological study of 10 cases","volume":"10","author":"Hu","year":"2017","journal-title":"Int. J. Clin. Exp. Pathol."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1097\/01.pap.0000213007.48479.94","article-title":"Podoplanin: A novel diagnostic immunohistochemical marker","volume":"13","year":"2006","journal-title":"Adv. Anat. Pathol."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"159","DOI":"10.1159\/000522411","article-title":"Gastric plexiform fibromyxoma resected using non-exposed endoscopic wall-inversion surgery: A case report","volume":"16","author":"Ebi","year":"2022","journal-title":"Case Rep. Gastroenterol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"2189","DOI":"10.3892\/ol.2016.4185","article-title":"Plexiform fibromyxoma with cotyledon-like serosal growth: A case report of a rare gastric tumor and review of the literature","volume":"11","author":"Kane","year":"2016","journal-title":"Oncol. Lett."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"648","DOI":"10.14309\/ajg.0000000000000491","article-title":"Plexiform fibromyxoma: A rare mesenchymal tumor found in the esophagus","volume":"115","author":"Tang","year":"2020","journal-title":"Am. J. Gastroenterol."}],"container-title":["Diagnostics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/6\/879\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,16]],"date-time":"2026-03-16T13:48:49Z","timestamp":1773668929000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-4418\/16\/6\/879"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,16]]},"references-count":16,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["diagnostics16060879"],"URL":"https:\/\/doi.org\/10.3390\/diagnostics16060879","relation":{},"ISSN":["2075-4418"],"issn-type":[{"value":"2075-4418","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,16]]}}}