Omental gastrointestinal stromal tumor: Arriving at a diagnosis with therapeutic options in the molecular era

Omental extragastrointestinal stromal tumors are rare neoplasms. We present a case of an elderly woman who was found to have a large solid and cystic pelvic mass of presumed ovarian origin with associated omental neovascularity. Histopathologic examination showed a mixed spindled and epithelioid tumor which was essentially negative for c-KIT and positive for smooth muscle markers by immunohistochemistry. A next generation sequencing panel was performed, analyzing the patient’s tumor for actionable mutations in 50 genes commonly associated with human cancers. Identification of a point mutation in PDGFRA  enabled accurate diagnosis and provided an option for targeted therapy for this rare tumor.