Chondrosarcoma arising in an enchondroma of the metacarpal bone - a case report.

Chondrosarcoma is a rare malignant tumour of proliferating cartilaginous tissue. It may arise as a primary lesion, or occur secondarily at the site of a previous benign lesion such as enchondroma . Primary chondrosarcomas are rare in the hand with a frequency of less than 0.5% to 3.2% of all chondrosarcomas, and are seen involving the phalanges, trapezium and trapezoid. Malignant transformation of a benign solitary enchondroma to secondary chondrosarcoma, especially in the hand, is extremely rare. We report a case, where the patient had developed a painful swelling in the 5th metacarpal bone of the right hand, 15 years back, which was diagnosed as enchondroma. Subsequently the patient presented with a 3-year history of increase in the size of the swelling at the same site, which on radiological and histopathological examination revealed malignant transformation into chondrosarcoma. We also discuss the differential diagnosis of chondrosarcoma. Keeping in mind the possibility of local recurrence and metastasis of chondrosarcoma, a ray amputation of the 4th and 5th digits of the right hand along with the mass was performed retaining the normal functioning of the hand.