Chondroma

CHONDROMA (chondroma), a tumor of cartilaginous tissue. It is usually composed of hyaline, less often of reticular and fibrous cartilage. Macroscopically, it is a tuberous, nodular tumor of dense, elastic consistency, consisting of separate amorphous lumps of cartilage connected to each other by layers of connective tissue with blood vessels running through them. The size of a chondroma varies; in some cases, they reach the size of an adult's head (chondromas of the pelvic bones). Histologically, chondromas are characterized by an uneven distribution of cells in the ground substance and their atypia; the cells are extremely polymorphic, sometimes lacking cartilaginous capsules, and sometimes 2-3 cells are included in one capsule. In cross-section, chondromas have a homogeneous appearance, are peculiarly transparent, with a bluish opalescence; however, their external appearance and consistency may change in connection with various degenerative processes. Especially frequent are petrification, edematous loosening, and mucinous degeneration of the interstitial substance with subsequent formation of cystic cavities filled with mucus-like contents. Such pseudomyxomatous transformation of a chondroma as a form of degeneration should not be confused with a true neoplasm of mucous tissue of the Wharton's jelly type, which occurs in connective tissue tumors and especially often in chondromas. These are so-called chondromyxomas (see Myxoma). Such metaplasias are observed frequently, leading to the formation of mixed chondromas; thus, a transformation of the chondroplastic substance into osteoid tissue with subsequent calcification and the development of bone marrow—osteochondroma—is often obtained. A chondroma is a benign tumor and possesses slow expansive growth. Sometimes a chondroma has a tendency toward intravascular growth and, while remaining anatomically benign, grows into blood and lymphatic vessels and may even produce metastases. Softened and mucinized chondromas are especially predisposed to ruptures into veins. In some cases, the tumor tissue becomes immature, undifferentiated cartilage cells—chondroblasts—appear, possessing sharp polymorphism; there is little ground substance, and in some places, cell multiplication proceeds so rapidly that the ground substance is not formed at all. Such tumors acquire infiltrating growth, a tendency toward recurrence and metastasis, and are malignant in their behavior—chondrosarcomas (see Sarcoma). Chondromas develop most often from detached and misplaced foci of cartilaginous tissue in the periosteum, bone marrow, and soft tissues, or from normal chondrogenic layers of articular surfaces and epiphyses, or from persistent cartilage rudiments in the bone. Such developmental defects appear as a result of irregularities of ossification in the embryonic and postnatal period, which may be facilitated by rickets, trauma, etc. Chondromas are congenital or appear at a young age; growing from pre-existing cartilage, they are naturally connected to the skeleton, although they can also be found in soft tissues. Chondromas of the skeleton, growing from the endosteum or bone marrow, are called enchondromas; they sometimes reach very large sizes, leading to atrophy and even erosion of the bone. So-called ecchondromas grow from the periosteum outward; they are most often localized in the region of the epiphyses and articular surfaces of the phalanges of the fingers; here they are often multiple, symmetrically located, and appear already at a young age. They often ossify and remain covered with cartilage only on the surface—ecchondrosis multiplex, s. ossificans. Chondromas of soft tissues are observed in the neck, in the kidneys, in the mammary gland, and in the lung. In the lung, they are encountered in the form of small nodules and are either true ecchondromas or, more often, stand outside of any connection with the cartilages of the bronchi, developing from misplaced foci of cartilage (see Lungs).