Abstract
Leiomyosarcoma (LMS) is a common form of soft tissue sarcoma. Primary colonic LMS is an extremely rare entity, comprising 1-2% of gastrointestinal malignancies. Primary mesenchymal sarcomas of the gastrointestinal system are rare and constitute just 0.1-3% of all gastrointestinal tumours. LMS is the most common variant of such tumours and represents just 0.12% of colorectal malignancies. We present a case of a 65-year-old female, who presented to the emergency department with 3 days history of obstipation and generalized abdominal pain. Radiology (X-ray and ultrasound) indicated a large pelvic mass compressing the sigmoid colon and its surrounding structures. Histopathological analysis indicated a primary LMS of the sigmoid colon. Diagnosis is established mostly postoperatively after histopathological evaluation. Prognosis and treatment modalities for this aggressive malignancy remain insufficient. LMS is relatively impervious to chemotherapy/radiotherapy. Our patient was treated by surgical excision of the tumour and referred postoperatively for adjuvant chemotherapy.