Atypical presentation of a retrorectal ancient schwannoma: a case report and review of the literature.

Retrorectal tumors are rare and frequently present either incidentally or with vague symptoms. Schwannomas of the presacral region are one variant described as benign tumors of neurogenic origin. The "ancient degenerative variant" is uncommonly reported. We present the case of a 37-year-old man presenting with symptoms of left renal colic, impotence, and left trochanteric pain. Computed tomography and magnetic resonance imaging of the pelvis showed a presacral mass with cystic changes and calcifications consistent with a schwannoma. The patient underwent an exploratory laparotomy with resection of the tumor, which subsequent analysis showed to be a schwannoma with ancient degenerative changes.