IMMUNOHISTOCHEMICAL ASSESSMENT OF TUMOR VASCULARITY IN RECURRENT CLARK-II MELANOMAS USING ANTIBODY TO TYPE-IV COLLAGEN

Thin melanomas, measuring 0.76 mm or less, are generally associated wi th an excellent prognosis. However, a certain subset of these seemingl y innocuous lesions have been reported to develop recurrences. Therefo re, the predictive values of currently accepted prognostic indicators have been questioned in thin melanomas. Several studies concerning tum or vascularity in melanoma and certain non-melanocytic malignancies su ggest that the degree of vascularization correlates with growth rate a nd biologic aggressiveness. In the present study, we determined the va scularity of a small group of Clark level II melanomas that resulted i n recurrence, and compared these results to an equal number of nonrecu rrent lesions with similar prognostic indicators. Blood vessels were l abeled by immunoperoxidase staining techniques for Type IV collagen, a nd quantified by image analysis. No statistical difference was found b etween the two groups when mean blood vessel counts and percent vascul ar area were measured. The recurrent tumors had a mean PVA of 4.68 com pared to 4.34 for the nonrecurrent group (p = 0.677). The mean blood v essel count beneath the recurrent group was 29.6 per 400 x field, and the corresponding value for the nonrecurrent group was 31.8 (p = 0.681 ). Our data is preliminary within this limited group of tumors, yet it suggests that tumor vascularity is not a distinctive prognostic indic ator by which eventual outcome can be predicted in thin Clark level II malignant melanomas.