Malignant peripheral nerve sheath tumor of the sigmoid colon: A case report and comparison with published cases

Malignant peripheral nerve sheath tumors (MPNSTs) are rare and aggressive soft tissue sarcomas. Its occurrence in the gastrointestinal tract, particularly in the sigmoid colon, is exceptionally uncommon and poses significant diagnostic and therapeutic challenges.

We report the case of a 46-year-old female who presented with a four-year history of intermittent rectal bleeding and lower abdominal pain. A diagnostic workup, including imaging and colonoscopy, revealed a large ulcerated polypoid mass at the rectosigmoid junction. The definitive diagnosis of MPNST was confirmed through histopathology and a comprehensive immunohistochemical panel, which demonstrated characteristic spindle cells positive for S-100 and SOX-10 and negative for markers of gastrointestinal stromal tumors (GIST) and smooth muscle neoplasms. The patient underwent successful complete surgical resection with clear margins, which resulted in favorable short-term outcomes.

This case highlights the diagnostic difficulties associated with colonic MPNSTs owing to their rarity and non-specific presentation. A comparison of eight published cases revealed variable outcomes, with recurrence rates approaching 40 %. This result underscores the indispensable role of immunohistochemistry in differentiating MPNST from other mesenchymal tumors. Complete surgical resection with clear margins remains the cornerstone for treatment.

Continued long-term follow-up is essential for patients with colonic MPNST given the aggressive nature and high recurrence potential of this malignancy.