Benign fibrous hamartoma of infancy: a case of MR imaging paralleling histologic findings.

Fibrous hamartoma of infancy is a rare fibrous tumor of the subcutaneous tissue in infants. While most case reports focus on the unique histologic appearance, which has traditionally been relied upon for diagnosis, there are few reports in the radiology literature of its appearance at MR imaging. In this report, the authors present the case of a 9-month-old male who presented with a soft tissue mass on the shoulder. The MRI findings in benign fibrous hamartoma of infancy parallel the three components of the lesion seen histologically, with an organized arrangement of fat interspersed among heterogeneous soft tissue bands composed of mesenchymal and fibrous tissue. When present, this characteristic appearance may allow the diagnosis to be suggested preoperatively.