Schwannoma of the Lower Leg with Malignant Transformation, a Case Report

Background: Peripheral nerve sheath tumors are benign or malignant. Schwannoma is a benign peripheral nerve sheath tumor originating from the Schwann cells that slowly grows eccentric to the nerve axis. Malignant transformation of a schwannoma is rare. Case presentation: A 73 years old women that presented in our medical service for other medical problems was diagnosed with a tumor of the lower leg (a small mass neglected by the patient for about 10 years). Considering the ultrasound features of the tumor, it was suspected to be a schwannoma. The tumor was resected and the histopathological assessment revealed a schwannoma with areas of malignant peripheral nerve sheath tumor transformation. LEARNING POINTS • Malignant transformation of the schwannomas is rare but should be considered given its poor prognosis. • We should distinguish between “ancient schwannoma” and malignant transformation of schwannoma since treatment and prognosis vary. • Imaging is not entirely reliable in differentiating benign from malignant peripheral nerve tumors.