Gastrointestinal stromal tumors (GIST) presenting in the liver: Diagnostic, prognostic and therapeutic issues.

CONTEXT: Extra-gastrointestinal stromal tumors (E-GIST) presenting in the liver are exceedingly rare and raise difficult diagnostic and therapeutic challenges.

METHODS: We report on two cases of liver E-GIST with different clinical presentations. We describe their clinical and imaging features, their histopathological and molecular characteristics, their treatment and their course.

RESULTS: The first case was that of a 56-year-old male presenting with a 10-cm liver mass; the initial diagnosis, made in 1986 from a biopsy sample, was leiomyosarcoma; liver transplantation was performed in 1987; no extra-hepatic tumor was found; the course was uneventful until 1999, when tumor recurrence was diagnosed along the initial biopsy route; after reevaluation of available material, the definitive pathological diagnosis was GIST; imatinib treatment resulted in major response; the patient died of end-stage kidney disease 22 years after the initial diagnosis and 9 years after tumor recurrence. The second case is that of a 59-year-old female presenting with a 23-cm abdominal mass connected to the liver; on biopsy, the tumor was diagnosed as epithelioid GIST with exon 11 KIT mutation; imatinib treatment resulted in stable disease.

CONCLUSIONS: The diagnosis of E-GIST must be for any sarcoma presenting in the liver and confirmed by immunohistochemical and molecular techniques. Treatment might require aggressive strategies, which can be successful despite apparently adverse histoprognostic factors.