| Summary: | Primary gastrointestinal stromal tumors (GIST) largely occur in the luminal gastro-intestinal tract and are extremely rare in the liver. On a molecular level, a small minority of GISTs are characterized by SDH deficiency. To date, SDH-deficient GISTs have been exclusively reported in the stomach, except a single duodenal primary. Here, we report a first of its kind occurrence of a SDH-deficient GIST presenting as a liver primary. The neoplastic cells showed an epithelioid morphology and were positive for vimentin, CD117/c-kit, DOG-1, and CD34 by immunohistochemistry. SDH-B immunohistochemistry was negative in the tumor cells, and retained in the background tissue. A dual-copy loss of SDHA gene was identified via multiplexed PCR and sequencing. Our case provides additional confirmation that SDH -deficient GIST can arise in locations other than stomach. Awareness of this entity is crucial for diagnosis and timely management and due to the potential health implications for family members in cases harboring a germline SDH mutation.
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