INTRACEREBRAL CARCINOMATOUS METASTASES

There are apparently several ways by which carcinoma may metastasize to the central nervous system. Briefly, these are: (1) by direct extension (along nerve sheaths, by bony invasion or from the meninges); (2) through the lymphatic vessels, usually in retrograde growth, and (3) via the blood stream, as carcinomatous emboli. The different routes of invasion result in different pathologic¹ and clinical pictures. Direct extension may be from a nearby primary focus, as in the case of carcinoma of the nasopharynx, or from a distant focus preceded by metastasis to a nearby structure, as in the case of carcinoma metastatic to the skull from the thyroid or the prostate. The resultant clinical picture is a combination of the symptoms produced by the structures primarily involved and those produced by the later growth into the central nervous system. Metastasis by the lymphatic route results usually in so-called meningitis carcinomatosa, with the