Clinical History: 31-year old woman with left foot numbness and pain for 6 months

Diagnosis: Left thigh schwannoma

MR Technique:

Imaging of the left lower extremity was performed on a 3T MR system. (A) Coronal T2-weighted TIRM (TR/TE 3000/38ms), (B) sagittal T2-weighted TIRM (TR/TE 3000/38), (C) axial T1-weighted TSE (TR/TE 500/11) and (D) axial T2-weighted TSE with Dixon fat suppression (TR/TE 2200/91) scans were acquired before the administration of intravenous contrast. Thereafter, contrast-enhanced T1-weighted TSE (TR/TE 550-700/11ms) images were acquired in the three orthogonal planes with Dixon fat suppression (E-G).

Imaging Findings:

There is a well-encapsulated, round lesion within the inter-muscular space of the posterior aspect of the left thigh. The lesion shows homogeneous isointense signal intensity on T1WI, and heterogeneous hyperintense signal intensity on T2WI. The sagittal image demonstrates the continuity of the mass with the sciatic nerve. On contrast-enhanced MRI, the lesion has markedly inhomogeneous enhancement, with irregular areas of low signal intensity centrally in the lesion, most likely representing hemorrhage or necrosis. The diagnosis of a schwannoma was confirmed by pathologic examination.