[The mineralization process in osteochondroma. A scanning electron microscopic study].

Thirty patients affected by osteochondroma were divided in two groups: 15 patients were in the age of development, and 15 patients had ended their development. The patients' age ranged from 4 to 42 years; 18 of them were males. The mineralization process (M.P.) of the osteochondral tissue was studied following hypochlorite treatment of the specimens. M.P. was particularly evident in patients during development and was characterized by round calcific nodules (calcospherites) which were linked to crossed collagen fibers. M.P. was morphologically similar to what is usually observed in normal and pathological specimens. Except in two cases, at the end of development the intertrabecular spaces were free of calcific material. In those two cases we observed a resumption of M.P. Mineralization was of calcospheritic type and started from islands of metaplastic cartilage. It was interpreted as a sign of possible transformation to peripheral chondrosarcoma. In a third case, osteoclastic activity caused deep, wide subperiosteal and trabecular erosion resulting in osteocartilaginous neoplastic tissue involution.