Gastrointestinal stromal tumour (GIST) is a rare tumour of gastrointestinal tract, comprising of 0.1-3.0% of all gastrointestinal malignancies. They are commonly found in stomach (60-70%), very rarely in rectum and anal canal (<5%). The present case report is of a large anorectal leiomyoma (142×80mm) arising from posterior rectal wall, with its unusual presentation of urinary retention. In our case, in view of its massive size, recurrence and malignant transformation, we planned abdominoperineal resection. Although size and histological grade play an important role, complete resection still is considered the most significant favorable prognostic factor.
Keywords: Gastro-intestinal stromal tumor; Leiomyoma; Urinary retention.