神經鞘瘤是生長速度緩慢的周邊神經鞘腫瘤，很少發生在後腹腔或骨盆腔。臨床上，發生在此部位的腫瘤除非十分巨大或已造成周圍的器官壓迫，通常不會出現症狀，因此一旦發現往往都十分巨大。在此，我們報告一巨大的薦骨前神經鞘瘤，此腫瘤壓迫周邊器官包括膀胱、輸尿管、乙狀結腸，並造成病患出現解尿疼痛、尿滯留、及腰痛的症狀。

Schwannomas are peripheral nerve sheath tumors with a slow growth rate. They rarely occur in the retroperitoneum or pelvis. Clinically, there are usually no symptoms when the tumors in these locations are not excessively large or cause compression of adjacent organs. Hence, they tend to be large when initially found. Herein, we present a case of a large presacral schwannoma which had displaced adjacent organs, including the urinary bladder, ureter, and sigmoid colon, with an initial presentation of voiding pain followed by urinary retention and flank pain. The tumor was completely excised, and the pathological report disclosed a benign ancient schwannoma. Recurrence was not noted after 8 months of follow-up.