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Epithelioid variant of gastrointestinal stromal tumor harboring PDGFRA mutation and MLH1 gene alteration: A case report
Author(s) -
Kobayashi Mizuho,
Inaguma Shingo,
Raffeld Mark,
Kato Hiroyuki,
Suzuki Shugo,
Wakasugi Takehiro,
Mitsui Akira,
Kuwabara Yoshiyuki,
Lasota Jerzy,
Ikeda Hiroshi,
Miettinen Markku,
Takahashi Satoru
Publication year - 2019
Publication title -
pathology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.73
H-Index - 74
eISSN - 1440-1827
pISSN - 1320-5463
DOI - 10.1111/pin.12830
Subject(s) - pdgfra , gist , stromal tumor , pathology , gastrointestinal tract , stomach , imatinib mesylate , cancer research , biology , mlh1 , stromal cell , tyrosine kinase inhibitor , epithelioid cell , imatinib , medicine , cancer , immunohistochemistry , colorectal cancer , myeloid leukemia , dna mismatch repair
Gastrointestinal stromal tumors (GISTs) are the most important and common mesenchymal tumors of the gastrointestinal tract, especially in the stomach. GISTs are usually driven by activating mutations in either KIT or PDGFRA genes. It is known that activating gene mutations predicts, to a certain extent, not only the morphology of the tumor cells but also a response to treatment with tyrosine kinase inhibitors. Here, we present a case of an epithelioid variant of GIST harboring PDGFRA and MLH1 gene alterations in the stomach of a 55‐year‐old Japanese woman. The tumor of 98 mm with multiple cysts showed exophytic growth from the gastric fundus. Histopathologically, it consisted of scattered medium‐sized epithelioid tumor cells in a loose myxoid background. Based on c‐kit and DOG‐1 immunoreactivity and a PDGFRA mutation (p.Trp559_Arg560del), the tumor was diagnosed as an epithelioid variant GIST. Interestingly, it had a gene alteration (p.Met524Ile) in the MLH1 gene of unknown pathogenicity. It was assigned to Group 3a (low risk for malignant behavior). After surgery, the patient has been on imatinib therapy and disease‐free for 10 months.