Fibrocartilaginous dysplasia: a variant of fibrous dysplasia.

Eight cases of fibrous dysplasia having enchondroma-like areas (fibrocartilaginous dysplasia) are reported. Four patients were male, four were female. The patients' ages ranged from 8 to 18 years (mean = 11.3 years). In seven cases, the lesions were located at the proximal femur while one was at the tibial diaphysis. Histologically, large, well-defined, sharply demarcated islands of hyaline cartilage tissue were seen within the typical fibro-osseous stroma of fibrous dysplasia. Some of the cartilage islands showed growth plate-like enchondral ossification at the periphery. Cartilage islands were mostly low in cellularity but infrequently, hypercellular areas were detected. Prolonged growth plate columns or developmental cartilage nests are considered in the origin of the cartilaginous component. In the differential diagnosis from benign and malignant chondroid tumours, the lack of atypia in the surrounding fibrous stroma is important.