Exostoses and Enchondromas

Abstract

An exostosis, whether solitary or part of multiple exostoses (a dysplasia, also known as osteochondromatosis), grows enchondrally from a misdirected cartilaginous cap. That cap closely resembles a conventional growth plate (Fig. 16). To emphasize that resemblance, I call the growth plate of the cartilage cap, “paraphysis” [para = alongside, from the Greek]. This paraphysis is subject to all the vagaries of the physis and acrophysis in cases of generalized abnormality. If ever you see a subject with exostosis who has rickets, I predict the loss of its ZPC and I would appreciate seeing the example. Growth of the exostosis from its paraphysis continues until the end of enchondral growth in adolescence.