Fibrocartilaginous mesenchymoma of bone.

Two bone tumors in children were characterized by prevalent low-cellular fibrous stroma of mature appearance and lobules of hyaline cartilage or chondroid tissue. Endochondral ossification was an additional finding. Clinically the two cases presented with osteolytic lesions of considerable size and relapsing course thus enhancing the suspicion of malignancy. The pathological diagnosis was controversial but both patients are disease-free several years after diagnosis. Histopathologically, the process duplicated the consecutive steps of embryonal endochondral bone formation. In a review of the pertinent literature it was found that these two cases reflect to a large extent the bone lesion reported in 1984 by Dahlin et al. and designated fibrocartilaginous mesenchymoma of the bone.