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Abdominal monophasic synovial sarcoma is a morphological and immunohistochemical mimic of gastrointestinal stromal tumour
Author(s) -
Wong Newton A C S,
Campbell Fiona,
Shepherd Neil A
Publication year - 2015
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.12593
Subject(s) - synovial sarcoma , pathology , gist , immunohistochemistry , pdgfra , sarcoma , gastrointestinal tract , leiomyosarcoma , medicine , stromal tumor , stromal cell , biology
Aims Synovial sarcomas may arise within retroperitoneal or pelvic tissues or, more rarely, within the luminal gastrointestinal tract. This case series aims to demonstrate how such primary abdominal synovial sarcomas may particularly mimic gastrointestinal stromal tumour ( GIST ) on both morphological and immunohistochemical grounds. Methods and results Four cases of primary abdominal synovial sarcoma were reviewed morphologically and with immunohistochemistry, fluorescence in‐situ hybridization with an SS 18 break‐apart probe, and KIT / PDGFRA mutation analysis. The four patients comprised two males and two females, with a median age of 42 years (range: 17–59 years). Two synovial sarcomas arose within the stomach, one within the small‐intestine mesentery, and the fourth within the retroperitoneum. All four tumours showed only a monophasic spindle cell component in the tissues available for review. All four tumours showed DOG 1 immunopositivity, and three coexpressed CD 117. Three tested cases did not show activating KIT or PDGFRA mutations, whereas all four cases showed chromosomal rearrangement of SS 18 . Conclusions A diagnosis of synovial sarcoma should be considered particularly if an abdominal spindle cell neoplasm shows a haemangiopericytomatous pattern and diffuse CD 99 and CD 56 immunopositivity. A confident distinction between abdominal synovial sarcoma and GIST requires KIT / PDGFRA mutation analyses and specific molecular testing for synovial sarcoma.