Rectal Leiomyoma on Routine Colonoscopy: Narrative Review and an Australian Case Report

Abstract Rectal leiomyomas are extremely rare benign smooth muscle tumors, accounting for under 1% of all rectal neoplasms. We report a case of an asymptomatic 64-year-old male who was found to have a small rectal polyp that histologically proved to be a leiomyoma during a routine colonoscopy. The polyp was completely excised endoscopically, and no further intervention was required. Histopathology revealed a circumscribed subepithelial spindle cell tumour consistent with a leiomyoma, with no evidence of malignancy. This case appears to be the first reported in Australia and raises the importance of thorough pathological evaluation of colorectal polyps, as even innocuous-appearing lesions can represent rare entities. We discuss the clinical and histological features of rectal leiomyomas and review the literature for similar cases. Although rectal leiomyomas are benign and only rarely recur, accurate diagnosis is crucial to distinguish them from gastrointestinal stromal tumors or leiomyosarcomas, which have different management and prognosis. Regular colonoscopic surveillance was planned for our patient, in line with standard screening guidelines.