Enchondroma

ENCHONDROMA, enchondroma, a tumor made of cartilaginous tissue, developing usually in the central parts of bones and osseous formations that do not normally contain cartilage, in contrast to exchondromas, which originate from the external parts of normally existing cartilage. The preferred sites of localization for enchondromas are the diaphyses of tubular bones, especially the phalanges of the fingers, where they are often multiple, in the form of nodes growing on top of one another. Occasionally, enchondromas of the pelvic bones are encountered, where they reach enormous sizes; they are rarer in other parts of the skeleton. Enchondromas of the bones, by growing into the bone, destroy it, which can lead to spontaneous fractures. Enchondromas are constructed for the most part of hyaline cartilage, are covered with perichondrium, and are divided into lobules by a stroma carrying blood vessels. The cartilage cells are very polymorphic, and their quantity varies greatly. Enchondromas, just like chondromas (see) in general, are very prone to various degenerative changes; most often, mucous degeneration of the interstitial substance is observed, with liquefaction and the formation of cystic cavities. Sometimes, a rupture of softened enchondromas through the integument is observed, resulting in non-healing ulcers and secondary suppuration. Calcification, as well as ossification of enchondromas, often takes place. An enchondroma can become immature and turn into a chondrosarcoma. However, it is difficult to draw a boundary between benign and malignant enchondromas, since the former can be malignant in their behavior, despite the maturity of the tissue; thus, they grow through bones, produce recurrences, and sometimes have a tendency to grow into blood and lymphatic vessels, giving metastases to regional glands, the lungs, and the liver. Widespread chondromatosis of the skeleton proceeds clinically as a malignant disease. Enchondromas are either congenital or appear at an early age. They develop from persistent, misplaced remnants of cartilage that have detached due to some irregularities in the ossification process during the embryonic or postnatal period. Apparently, rickets can play the role of an etiological factor, especially since it is precisely in this disease that enchondromas are observed particularly often. Great importance in the occurrence of enchondroma is attributed to trauma to the bones; it is possible that in the process of regeneration following this, as well as during inflammatory processes, metaplasia of undifferentiated connective tissue into cartilaginous tissue occurs.