[Chondroma, chondroblastoma and chondromyxoid fibroma]

Chondromas are benign tumors characterized by the formation of mature cartilage. Typically, they involve the short bones of the hands and feet. The lesions may be either solitary or multiple as part of enchondromatosis affecting several bones. Cases of multiple enchondromatosis with predominantly unilateral distribution are generally referred to as "Ollier's disease" or when accompanied by multiple hemangiomas as "Maffucci's syndrome". In cases with multiple chondromas there is considerable risk of malignant transformation (approximately 50%). Treatment of single lesions (curettage and bone grafting) is usually uneventful, but any therapeutic approach to Ollier's disease or Maffucci's syndrome should be tailored to the individual distribution of lesions in the most severely deformed extremities. Chondroblastomas are uncommon benign tumors that are almost invariably situated in the epiphyses of long bones adjacent to the epiphyseal cartilage plate. Histologically, they are characterized by round or polygonal chondroblasts with focal accumulation of osteoclast-like giant cells. Intercellular substance is scanty, and calcification occurs typically at focal areas. Lung metastases are reported in rare single cases with high survival rates after local resection, indicating low-grade malignancy. Only a few recurrences have been reported following curettage and bone grafting. Avascular necrosis or chondrolysis with subsequent secondary osteoarthrosis may occur after surgical treatment of chondroblastoma of the upper femur epiphysis. These severe indirect sequelae should be considered both when planning surgery and during follow-up. Chondromyxoid fibromas are rare benign tumors that are mostly diagnosed in the second and third decade; they are mainly found in the proximal tibial metaphysis. Histologically, there are areas of chondroid, myxoid, and fibrotic tissues, of which the myxoid component is characteristic for chondromyxoid fibromas.(ABSTRACT TRUNCATED AT 250 WORDS)