A case of malignant melanoma is presented because of the unusual manner in which the malignant melanoma metastasized. When malignant melanomas metastasize to lymph nodes, they usually metastasize to the nodes that drain the area in which the tumor is situated without showing any perceptible involvement of the intervening skin. In this patient, the melanoblasts followed the superficial lymphatics over the ilium to the pubic region before the inguinal lymph nodes were palpable (Figs. 1 and 2).
Mohs and Lathrop1 recently stated that some cancers show a peculiar affinity for some specific tissue structure, which they follow selectively for unexpectedly great distances. They enumerated the following structures which certain cancers showed particular affinity for: (1) dermis, (2) fascial planes, (3) periosteum, (4) perichondrium, (5) embryonic fusion planes, (6) nerve sheaths, (7) lymphatic vessels, and (8) blood vessels. The malignant melanoma herein reported showed an affinity for lymphatic vessels.