Congenital lymphangioma. (Original.)
Fig. 83
Lymphangioma of lower extremity. (Original.)
5. Tumors of Nerve Elements.
Glioma.
—Glioma is a malignant tumor developing directly from actual nerve structure or that of the original nerve elements, and is clinically allied to the sarcomas. It arises from the neuroglia, and hence is confined to the central and peripheral nervous system, mainly the former. It is most common in the brain, the cord, and in connection with the optic nerve and fundus of the eye. It is often extremely vascular, the vessels being sacculated, and is usually met with in solitary form. When near the surface of the cortex such a tumor may appear like a great convolution (Virchow). In the basal portions of the brain it may attain considerable size. In the cord it is rare, usually limited to the cervical region. In the orbit and eye it may produce marked exophthalmos. It is more frequent in the young than in the aged.
Glioma is an exceedingly malignant form of tumor, and operation is rarely performed sufficiently early to more than prolong life. Dissemination by continuity is the rule rather than metastasis. It kills usually by its pressure effect on the nerve centres.