Rectal schwannoma mimicking malignant rectal cancer: a case report

Rectal schwannomas are exceptionally rare benign neurogenic tumors arising from Schwann cells of the enteric plexus. They account for a very small proportion of gastrointestinal schwannomas and often mimic malignant spindle-cell tumors such as gastrointestinal stromal tumors or leiomyosarcomas, posing a significant diagnostic challenge. Accurate differentiation is essential to avoid unnecessary radical surgery.

We report a 38-year-old woman presenting with abdominal pain, constipation, hematochezia, and weight loss. Imaging and colonoscopy revealed a 4 × 5 cm rectal mass located 5 cm above the dentate line. Initial pathology suggested a malignant spindle cell tumor, but immunohistochemistry confirmed S100 and SOX10 positivity and CD117/DOG1 negativity, consistent with a rectal schwannoma. The patient underwent a laparoscopic total mesorectal excision with clear surgical margins. Postoperative recovery was uneventful, and no recurrence has been observed during follow-up.

Due to their nonspecific presentation and radiologic overlap with other rectal neoplasms, rectal schwannomas are frequently misdiagnosed preoperatively. Histopathologic and immunohistochemical analysis remains the cornerstone of diagnosis. Surgical excision with negative margins is curative, while the role of adjuvant therapy is limited. Long-term follow-up is recommended due to uncertain patterns of recurrence.

Rectal schwannomas are rare entities that can simulate malignant tumors both clinically and radiologically. Comprehensive diagnostic work-up and complete surgical resection are crucial for accurate diagnosis and favorable outcomes. Further studies are required to establish standardized management and follow-up protocols.