Rectal synovial sarcoma case report - An unexpected cause of acute lower gastrointestinal bleeding.

Introduction and importance: Acute lower gastrointestinal bleeding is one of the most common causes of hospital admission. However, massive bleeding is uncommon and is mainly due to hemorrhoidal bleeding in elderly patients receiving anticoagulant therapy. We present a rare case of a massive rectal haemorrhage with an uncommon cause.

Case presentation: A 60-year-old woman was admitted to the emergency department with a two-day history of lower gastrointestinal bleeding. During digital rectal examination and anoscopy, a palpable mass located 8 cm from the anal verge with severe bleeding was detected. Subsequent rectosigmoidoscopy revealed a bulge in the rectal wall with mucosal ulceration and signs of recent bleeding. The CT-scan revealed a 74 × 41 mm locally advanced rectal mass and three hepatic lesions (segments 6 and 7). Pathology results were compatible with synovial sarcoma (SyS). The case was discussed by a sarcoma board, and the patient underwent doxorubicin plus ifosfamide resulting in a significant reduction of the metastatic lesions and complete remission of the primary lesion on MRI. Following multidisciplinary discussion, low anterior resection of the rectum with terminal colostomy and right posterior sectionectomy were performed. At 23 months follow-up, the patient shows no signs of recurrence.

Clinical discussion: SyS are uncommon malignant tumours, accounting for 5-10 % of all soft tissue sarcomas. Metastatic SyS carries a poor prognosis.

Conclusion: Gastrointestinal involvement is exceptionally rare and, to the best of our knowledge, this is the third rectal SyS case reported in the literature. Because of this, SyS should be managed in sarcoma referral centers.