Posttraumatic Pseudolipoma (Fat Necrosis) Mimicking Atypical Lipoma or Liposarcoma on MRI

We report a case of a 53 year old female who presented with a painless mass over her left greater trochanter. Evaluation with MRI and ultimately biopsy led to a diagnosis of fat necrosis. If this diagnosis had been considered with greater confidence, a conservative approach could have been taken and biopsy avoided. In patients with lesions demonstrating classic locations and imaging features of fat necrosis, observation without biopsy is appropriate.