Rectal Gastrointestinal Stromal Tumor Poor Response to Imatinib: A Case Report.

A 63-year-old man presented with persistent constipation lasting 6.5 months. Digital rectal examination revealed a soft-tissue lesion near the anal verge without bleeding. Further evaluation identified a rectal mass. Treatment with imatinib for 6 months showed no significant response. The patient subsequently underwent surgical resection, with favorable short-term clinical outcomes.