A 46-year-old female presents with episodes of nausea. Endoscopy shows a 3 cm submucosal mass in the stomach. The tumor cells are predominantly oncocytic, with abundant vaguely granular eosinophilic cytoplasm, tumor necrosis, and invasion into the subserosal connective tissue. Focally, the tumor demonstrates higher-grade primitive areas. Immunohistochemistry shows that the tumor cells are positive for S100 and SOX10, while negative for keratin, synaptophysin, chromogranin, desmin, MelanA, DOG1, and CD117. Genetic studies confirm an EWSR1-ATF1 fusion.
|Daniel (Dan) P. Larson, M.D.
Resident, Anatomic and Clinical Pathology
|Jennifer Boland Froemming, M.D.
Consultant, Anatomic Pathology
Associate Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine