Chondromas usually occur at sites of pre-existing cartilage, the epiphyseal line, and so forth, and involve the epiphysis and diaphysis. There is a greater tendency to growth into the epiphysis, where, at times, it apparently remains until late in the history of [See Fig. 7 in Source Pdf.] the growth. The periosteum is not involved and appears normal by x-ray and at operation. The cortex may appear normal by x-ray and at operation unless it is thinned by pressure or bulges out, or unless it is involved with the medullary substance, when it appears as a homogeneous tumor.
Chondromas do not invade the soft periosseous tissues as is so frequently seen in malignant tumors. Trauma appears to be an etiologic factor, especially in the growths on the hands. Although these tumors occur most frequently in the young, they may occur late in life, and should be taken into consideration when other factors indicate benign tumor formation. Superimposed bursae may become injured, and a rapid swelling or a rapid growth may follow which is suggestive of malignant change or degeneration.
The contents of the tumor usually consist of pure hyaline cartilage in which a fine supporting framework of connective tissue is found, or it may be crossed by a bony network and trabeculations. The latter produce definite coarse lines in the x-ray picture which ramify in an irregular manner across the more transparent areas.
The history of the case, the clinical examination and the x-ray findings may present such a complex picture that it will be necessary to resort to surgery and pathologic examination in order to arrive at a correct diagnosis. Even benign chondromas may recur, and such recurrences should be carefully watched for malignant change. None of the cases in this series showed subsequent malignancy. It should be remembered that degenerating processes may cause cysts, probably due to pressure-degeneration and poor vascular supply. The x-ray is of great value in determining the size, location, and difference between the single and multiple varieties of chondromas, but it should not be depended on in making a definite diagnosis. There was a fairly similar picture between the giant-cell tumor and the chondroma in some of our cases. Surgical intervention in cases of chondroma should be conservative. The prognosis is favorable.
SECTION OF ORTHOPAEDIC SURGERY, MAYO CLINIC, ROCHESTER, MINN.