[Presacral malignant peripheral nerve sheath tumor in a patient with von Recklinghausen disease: case report].

A 32-year-old woman was admitted to our institution with dysuria and pain in the left foot. She was diagnosed with von Recklinghausen disease based on the physical findings, and an elastic, firm mass was palpable with the fingertip on the posterior wall of the rectum. Ultrasonography, computed tomography, and magnetic resonance imaging revealed a solid tumor, which measured 8 cm in diameter, in the presacral space. The tumor was diagnosed as a presacral solid tumor and the tumor was extirpated. The specimen was a 10 x 8 x 8 cm yellowish solid tumor weighing 250 g. The histopathologic diagnosis was malignant peripheral nerve sheath tumor (MPNST). Presacral MPNST is rarely diagnosed in the early stage, and the prognosis for MPNST patients with von Recklinghausen disease is relatively poor. Tumor resection with wide surgical margins is necessary and close follow-up after surgery is mandatory.