Gastrointestinal stromal tumor of the rectum: A case report with emphasis on MRI-pathologic correlation

A 73-year-old male presented with a 6-month history of incomplete defecation, prompting investigation. Physical examination revealed a smooth, broad-based rectal mass located at the 12-4 o'clock position, with no mucosal ulcerations or bleeding. MRI imaging displayed a well-defined, round mass (3.5 cm × 2.8 cm) exhibiting homogeneous intermediate signals on T1-weighted imaging and hyperintensity on T2-weighted imaging, along with restricted diffusion indicated by low apparent diffusion coefficient values. Surgical intervention involved complete resection of the mass via the anus, with gross examination revealing grayish-red fragmented tissue. Histopathological assessment identified spindle cells with high mitotic activity, confirmed by immunohistochemistry as DOG-1 positive, consistent with gastrointestinal stromal tumor (GIST). Postoperative CT indicated complete resection, and at the 2-month follow-up, the patient's symptoms had resolved. This case underscores the significance of early diagnosis and surgical management of rectal GIST in patients presenting with nonspecific gastrointestinal symptoms.