Epiphyseal chondromyxoid fibroma with prominent adipose tissue: an unusual radiologic and histologic presentation.

Chondromyxoid fibroma (CMF) is a rare benign tumor that typically develops in the metaphyseal intramedullary portion of long bones. The tumor may extend into the diaphysis or, seldom, into the epiphysis, but purely epiphyseal lesions are extremely rare, with only 2 cases having been reported in the literature. In this article, we report the case of a 51-year-old African American woman. Radiographs showed a well-defined, subarticular lytic lesion in the epiphysis of the right proximal tibia extending to the adjacent metaphysis. Histologic sections of the curetted specimen showed lobules of spindled and stellate cells in a zonal distribution on a background of abundant chondromyxoid stroma, features characteristic of CMF. In addition, mature adipose tissue streamed throughout the lesion-a unique finding that until now had not been recorded in CMF at any location. Thus, chondromyxoid fibrolipoma may be an appropriate term for this lesion.