Synovial desmoplastic fibroblastoma of hip joint with bone erosion.

A 78-year-old woman presented with pain at the left hip. Initial radiographs showed minimal age-related changes. Over the next 2 years she developed large erosions in the left femoral neck and proceeded to hip replacement. Histological examination showed bland spindle cells in a loose and hyalinised collagenous stroma considered to represent a desmoplastic fibroblastoma (collagenous fibroma). This is the first reported case of synovial desmoplastic fibroblastoma.