This tumour is composed of cartilaginous tissue. The cartilage may be liyaline (see Fig. 75) or fibrous, generally the latter, and the matrix is not infrequently rather soft. The tumour is also intersected with fibrous bands which carry blood-vessels that nourish the tissue. If a cartilaginous tumour grows in connection with and out from cartilage it is called an Ecchondrosis, but if, as in the majority of cases, it grows in connection with other tissues, then it is called an Enchondroma. The term chondroma of course includes both.

The ecchondroses are usually small unimportant outgrowths chiefly of the cartilages of the septum nasi, larynx and trachea and ribs.

Virchow has described an interesting form of so-called ecchondrosis at the basilar portion of the occipital and sphenoid bones. The basilar parts of these bones are formed from cartilage, and in adult life they are united, forming a single bone (os tribasilare). The junction takes place irregularly by a kind of toothed union. In this process a little bit of cartilage may be omitted, and this sometimes develops into a little tumour just under the basilar artery to which it may be adherent. It will be seen that we have here an actual instance of a little piece of embryonic tissue left over to develop afterwards into a tumour. This little tumour sometimes undergoes a remarkable change; the cells swell up and become like those of the chorda dorsalis, but in other cases it ossifies.

The cartilaginous loose bodies in joints are sometimes regarded as originally outgrowths from the cartilages or synovial fringes which have been broken off and grown after their separation.

Enchondromas are mostly met with in connection with Bones. As bones are developed out of cartilage for the most part, it may be supposed that little bits of the embryonic cartilage are left over and develop into tumours afterwards. The enchondromas of bone may be divided into central and peripheral, according as they originate in the medulla or at the surface. The central enchondromas are met with chiefly in early life, and may be congenital. They occur especially in the fingers and toes, which may be the seat of multiple tumours as in Fig. 76. These tumours begin inside the phalanges or metacarpal bones, or, less frequently, the analogous bones of the foot. Growing inside the bones they may be for a time unperceived, but afterwards swell up the bones and may even burst through the external shell. These tumours often show a local malignancy, growing by the formation of new nodules in the tissue around. The peripheral chondromas are met with most frequently on the femur and pelvis, and most rarely on the bones of the face and skull.

Chondroma of bone.

Fig. 75. - Chondroma of bone. I n the lower part the matrix is hyaline; in the upper part calcification and ossification have occurred, x 80.

In soft parts chondromas are found occasionally, but are commonly mixed with fibrous, mucous, glandular, sarcomatous, or cancerous tissue. They are particularly frequent in glands, as the testes, ovaries, and salivary glands. In these situations they are occasionally found to follow chronic irritations.

Multiple central enchon drornata of fingers.

Fig. 76. - Multiple central enchon-drornata of fingers. (Cornil and Ras-vier).

In their form chondromas are generally rounded tumours and distinctly encapsuled, but if large they are lobulated.

It has already been said that the chondromas are often mixed with other tissue, and it is to be added that secondary changes are not infrequent. They sometimes soften, and this is frequently due to partial transformation into mucous tissue. This is particularly the case with the glandular enchondromas. On the other hand, those of bone are liable to undergo calcification and ossification (Fig. 75).

Lastly, chondromas are liable, as has already been said, to show a certain malignancy, forming secondary tumours, especially in the lungs. This is connected with the frequently mixed character of these tumours and their association especially with sarcomas and cancers.

Literature

A. Cooper, Surgical Essays, 1818; Virchow, Geschwiilste, i., 485; Murchison, Edin. Monthly Jour., 1852; Syme (Congenital enchondroma), Lancet, 1855, p. 116.