Lymphatics in primary cutaneous melanoma.

Using Ulex europaeus I lectin (UEA1) to demonstrate endothelial cells, we have previously shown that frequency of capillary invasion correlates closely with maximum tumor thickness in primary cutaneous melanoma. UEA1 demonstrates both vascular and lymphatic capillaries; however, only vascular capillaries possess basement membranes. In order to ascertain whether these capillaries were lymphatic or vascular, we employed a double staining technique, using UEA1 in conjunction with a monoclonal anti-type IV collagen antibody. We studied 21 primary cutaneous melanomas. Seven of the 21 included lymphatic capillaries, while 14 did not. These lymphatic capillaries were very sparse and appeared to be residual dermal lymphatics rather than a result of lymphangiogenesis. Lymphatic permeation by melanoma was not seen in any of the tumors studied. There was no apparent association among tumor thickness, level of invasion, growth phase, necrosis, regression or mitotic index, and presence of lymphatics within the melanomas. Although scanty lymphatics are present in some primary cutaneous melanomas, this study does not suggest that lymphatic permeation plays a major role in the spread of melanoma to locoregional lymph nodes.