[Benign chondroblastoma].

Analysis of 12 observations with a typical histological appearance revealed only in one case a local relapse. In two tumours the authors found a structure encountered in aneurysmatic osseous cysts and in one case, due, to the presence of a major number of osteoclasts, the differential diagnosis with a giant-cell bone tumour was rendered more difficult. Electron microscopic examination revealed that tumours of this type are formed by cartilage cells differentiated in different ways. In cellular areas two main types of cells are found: light and dark ones. Some of the elements of both types had multilobular nuclei.