An ulcerated ileal leiomyosarcoma identified by single-balloon enteroscopy despite nondiagnostic mucosal biopsies

Gastrointestinal leiomyosarcoma is a rare malignant smooth-muscle neoplasm that may be difficult to diagnose using superficial mucosal biopsy. A 44-year-old woman presented with chronic intermittent abdominal pain and microcytic hypochromic anemia. Retrograde single-balloon enteroscopy identified an ulcerated, stenosing lesion in the distal ileum, whereas six forceps biopsy specimens showed only inflammation and granulation tissue. Segmental ileal resection was therefore performed because malignancy remained strongly suspected. Histological examination demonstrated a spindle-cell neoplasm with focal myxoid change and marked mitotic activity. The tumor cells expressed smooth muscle actin, with focal desmin and calponin expression, and were negative for DOG1, CD34, pancytokeratin, S-100, and HMB45. Specialist pathological review supported the diagnosis of FNCLCC grade 3 ileal leiomyosarcoma. After multidisciplinary discussion, the patient received six cycles of individualized adjuvant chemotherapy. At the latest radiological assessment, approximately 32 months after surgery, there was no evidence of local recurrence or distant metastases. This case highlights the value of single-balloon enteroscopy in localizing suspicious small-bowel lesions despite nondiagnostic mucosal biopsies.