Conspicuous angiotropism of malignant melanoma involving the brain: implications for extravascular migratory metastasis.

Angiotropism is the presence of tumor cells closely apposed to the abluminal surfaces of blood and lymphatic vessels without intravasation. Previous studies have strongly suggested that angiotropism in melanoma could be a marker for extravascular migratory metastasis, the migration of tumor cells along the external surfaces of vessels. We describe for the first time a patient with malignant melanoma of the brain most likely metastatic, which was floridly angiotropic as evidenced by extensive spread of melanoma cells along the external surfaces of brain microvessels. The location of this angiotropic melanoma in the brain, together with the analogies between extravascular migratory metastasis and the neoplastic glial invasion of the nervous system, reinforces the hypothesis of extravascular migration of melanoma cells as a means of tumor spread, particularly along the abluminal surfaces of vessels, in the brain and in other organs.