SMARCA4-deficient thoracic sarcoma: report of a case and insights into how to reach the diagnosis using limited samples and resources

Publication date: Available online 7 June 2017
Source:Human Pathology
Author(s): Satoshi Kuwamoto, Michiko Matsushita, Kenichi Takeda, Natsumi Tanaka, Yukari Endo, Akira Yamasaki, Kenichi Kohashi, Yoshinao Oda, Yasushi Horie
SMARCA4-deficient thoracic sarcoma is a recently proposed new entity of soft tissue sarcomas with an undifferentiated round cell morphology that is diagnostically challenging. Here we report a case of this tumor where the diagnosis was established using limited samples and resources. A woman in her early 30s developed two intrathoracic masses. Biopsies for these lesions showed sheets of undifferentiated round/rhabdoid cells that retained SMARCB1 expression. Further analysis revealed a reduced SMARCA4 expression and a complete loss of SMARCA2 expression in tumor cells. Subsequent sanger sequencing identified a nonsense c.1546A>T (p.516Lys>Ter) mutation in SMARCA4 and confirmed the diagnosis. Our case highlighted clinicopathological correlation and rational use of tissue sections for immunohistochemistry may enable to diagnose this tumor even when only limited samples are available. Recognition of this new entity is important for further understanding of the disease and the future development of specific therapies.



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