Duodenal epithelioid gastrointestinal stromal tumor with prominent granular cell features.

Gastrointestinal stromal tumors are a group of mesenchymal tumors arising from the wall of the gastrointestinal tract that are characterized by activating mutations in KIT or PDGFRA. Their proper recognition is important clinically because of their potential responsiveness to targeted therapies. We report a case of duodenal gastrointestinal stromal tumor with a highly unusual epithelioid morphology that had an appearance reminiscent of a steroid producing neoplasm, such as an adrenal cortical neoplasm or, alternatively, a renal cell carcinoma variant. The recognition of the current tumor as a duodenal gastrointestinal stromal tumor was prompted by its apparent location in the duodenal wall. Ancillary immunohistochemical and molecular sequence analyses were necessary to confirm the diagnosis as a gastrointestinal stromal tumor. The current case illustrates the importance of considering gastrointestinal stromal tumor in the differential diagnosis of any epithelioid tumors in the gastrointestinal tract or the abdominal-pelvic cavity.