Soft tissue chondroma of Hoffa's fat pad.

We report mutimodal imaging findings of an extraskeletal chondroma of the Hoffa's fat pad. Plain radiographic or CT scan studies demonstrate a large soft tissue mass with calcifications and central ossification, characteristic features of these tumors. Magnetic resonance (MR) imaging shows heterogeneous signal due to polymorphic histopathological appearance. Correlation between MR imaging and plain film or CT findings is essential to restrict differential diagnosis. The knowledge of this particular pathology is the key to the diagnosis.