Malignant triton tumor below the peritoneal reflection: a case report.

Malignant triton tumor (MTT) is a rare subtype of malignant peripheral nerve sheath tumors (MPNSTs) histologically defined by rhabdomyoblastic differentiation. MTTs are primarily found in the head, neck, extremities and trunk, but rare cases of MTT within the buttock, the mediastinum and the retroperitoneum have also been documented. We present the case of a 47-year-old male patient who initially presented with right flank pain and hematuria in July 2019, who was found to have a large pelvic mass below peritoneal reflection. Complete resection of the mass was performed, and pathology identified the mass as a MTT.