Extraskeletal chondromas are relatively uncommon benign cartilaginous tumors of the soft tissue and well known to pose a considerable diagnostic problem because of histological variations including the immature appearance of their tumor cells. Recently, we have experienced a case of extraskeletal chondroma mimicking benign chondroblastoma.
The patient was a 47-year-old woman who complained of a painful subcutaneous swelling on the radial aspect of 4th proximal interphalangeal (PIP) joint in the left hand for 6 months. Radiologic examination of the 4th finger revealed a 1cm-sized soft tissue mass. Histologically, the tumor was characterized by a lobulated mass which was composed of dense proliferation of chondroblast-like cells admixed with a few multinucleated giant cells of osteoclastic type.
However, there were focal areas of typical chondroma which showed lace-like intense calcification around the differentiated chondrocytes.