From Unexplained Iron-Deficiency Anaemia to Ileo-Ileal Intussusception: A Case Report of Primary Small Bowel Leiomyosarcoma.

Intussusception refers to the telescoping of a gastrointestinal segment into an adjacent distal segment. Adult intussusception is rare and is often associated with a lead point (LP). Primary small bowel leiomyosarcoma (LMS) is a malignancy of smooth muscle cells that arises from the bowel wall and can serve as an LP for intussusception. We report the case of a man in his 60s with long-standing unexplained iron-deficiency anaemia (IDA) who underwent multiple upper and lower gastrointestinal endoscopic investigations, but the source of the anaemia could not be identified. Years after the initial diagnosis of IDA, he presented with abdominal pain, nausea, vomiting, constipation, and an unintentional weight loss of 6.4 kg over a 10-day period. Computed tomography of the abdomen and pelvis demonstrated ileo-ileal intussusception. Emergency laparoscopic-assisted segmental small bowel resection with side-to-side anastomosis was performed. Histopathological examination demonstrated a spindle-cell malignancy with mucosal ulceration. The ulcerated intraluminal tumour represented a plausible source of chronic occult gastrointestinal blood loss and subsequently served as the LP for intussusception. Immunohistochemistry confirmed small bowel LMS and excluded gastrointestinal stromal tumour. His postoperative recovery was uneventful, and he was discharged three days after surgery. At the two-month follow-up, his anaemia had resolved without perioperative blood transfusion, although mild residual iron deficiency remained.