Enchondroma is a benign neoplasm consisting of cartilage tissue. It is localized intraosseous, usually in the zone of diaphysis and metadiaphysis of tubular bones. It most often affects small tubular bones of the hands and feet, can be either single or multiple. As a rule, it is asymptomatic, large enchondromes can cause deformity of the limb segment. Sometimes the enchondroma is complicated by a pathological fracture. Degeneration into a malignant tumor is rarely observed. The diagnosis is confirmed by radiography, CT and biopsy. Surgical treatment – removal of neoplasia.
D16 Benign neoplasm of bones and articular cartilage
Enchondroma is a benign tumor, it is a site of mature hyaline cartilage of heterotopic localization (located in anatomical zones where cartilage tissue is normally absent). It is usually localized in the bones, but cases have been described when enchondromes were found in the lungs, subcutaneous fat, ovaries, mammary glands, brain tissues, etc. Enchondromes account for about 10% of the total number of neoplasms of bone and cartilage tissue.
In more than half of cases, enchondromas are diagnosed in people younger than 40 years. The peak incidence occurs at the age of 11-16 years. Enchondromes can be single or multiple. Multiple enchondromes are observed in Ollier’s disease and Maffucci syndrome. In their structure, multiple formations are almost similar to single chondromes, but differ from them by a greater ordering of the structure. Despite the slow growth and low tendency to malignancy, enchondromes are considered as potentially malignant neoplasms, therefore oncologists and traumatologists usually recommend their surgical removal.
Tumors develop from areas of cartilage located in places where cartilage tissue is normally absent. Researchers have found out that heterotopic localization of cartilage is a consequence of a violation of the ossification process in the prenatal period and in the first years of a child’s life. The immediate cause of ossification has not yet been clarified, but it has been established that this pathology is not associated with exposure to harmful substances or radiation. It is assumed that the growth of the enchondroma from a heterotopically located area of cartilage is provoked by traumatic lesions and inflammatory processes in the bone tissue.
The tumor is a mature hyaline cartilage with a lost structure. Unlike normal cartilage, the cells of the enchondroma are located randomly, their size and shape can vary greatly. Neoplasia is covered with suprachrustum and has a lobular structure. Small foci of ossification usually form inside. Dystrophic tissue changes are characteristic, manifested by dilution of the intercellular substance and the formation of cysts. With malignancy, the tumor cells become larger, the number of cells with two nuclei increases.
The “favorite” localization of enchondromes is the short tubular bones of the feet and hands. It is also possible to damage the humerus and femur. In the area of other long bones, single enchondromes are rare. Sometimes flat bones are affected: pelvic bones, shoulder blade, etc. With multiple chondromatosis (Ollier’s disease), tumors can be detected in the area of one half of the body (right or left) or in the area of one limb. Less often, the pathological process extends to both lower extremities.
Clinical symptoms are usually poor. Small tumors are asymptomatic and become an accidental finding during X-ray examination for other reasons. With large enchondromes, deformations of the affected segment occur. Palpationally, a tumor is defined as a dense painless formation. Unpleasant symptoms appear when adjacent anatomical formations (vessels, nerves) are squeezed. Large neoplasias located near the joints can provoke arthralgia, movement restriction and synovitis.
Cartilage tissue is not as dense and strong as bone. It is not adapted to high static and dynamic loads. If the enchondroma occupies the entire diameter of the bone or a significant part of it, the strength of the bone in this place decreases sharply. In such conditions, even a small injury becomes enough for the occurrence of a pathological fracture. Fractures are accompanied by pain, pathological mobility, crepitation and deformity of the limb. Unlike ordinary fractures, there is no data on intensive traumatic effects in the anamnesis.
Diagnosis of enchondroma is usually simple. Radiographs of long tubular bones reveal a centrally located oblacoid enlightenment. In the zone of enlightenment, darker areas may be detected – foci of calcification. Tumors in the area of short tubular bones usually look homogeneous and occupy most of the diameter or the entire diameter of the bone. The cortical layer is not broken. A similar pattern is determined on a CT scan of the bone, the advantage of computed tomography is the ability to examine the structure of the enchondroma in more detail.
If a tumor is suspected of malignancy, a cartilage biopsy is performed. Malignancy is indicated by enlarged cartilage cells of rounded or irregular shape and the presence of a large number of multinucleated cells. To increase the reliability of the diagnosis, the material is always taken in several sites, since at the initial stages of malignancy, the zones of normal cells in the enchondrome alternate with the zones of degeneration. Differential diagnosis of enchondroma is carried out with giant cell bone tumor, fibrous dysplasia, bone cyst and chondrosarcoma.
The tactics of treatment depends on the localization of the neoplasm. Tumors of short tubular bones are not prone to malignancy, therefore, with such an arrangement of the enchondroma, dynamic observation is possible, including regular examinations and repeated radiography of the affected segment. Due to the potential danger of encondroma malignancy of long tubular and flat bones, specialists in the field of clinical oncology usually suggest that patients remove the tumor immediately after diagnosis.
Growing enchondromes of short tubular bones are excised within healthy tissues. When large defects are formed, homo- or allografts are used. With tumors of flat and long tubular bones, an extended surgical intervention is necessary – segmental resection of the bone with subsequent replacement of the defect.
Prognosis and prevention
With timely complete excision of the neoplasm, the prognosis is usually favorable, complete recovery is observed. Relapses are quite rare. The probability of malignancy of primary neoplasia is low. Recurrent enchondromas deserve special attention because of the high probability of malignancy. In such cases, ablastic (extended) resections are performed. Preventive measures have not been developed.
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