This Multiplex application serves as a
tool to identify the proliferation rate of melanocytic lesions in cases in which
melanocytes are sparse; there are dense lymphocytic infiltrates; and melanocytes
are admixed with fibroblasts. In general, a higher proliferative fraction is
seen in melanoma than in melanocytic nevi. There are many types of nevi, and
some simulate melanoma closely. If the Multiplex stain shows a very low Ki-67
(DAB) labeling rate in MART-1/Tyrosinase positive cells (Fast Red), this favors
benignity. A high rate, especially toward the deep part of a melanocytic lesion
raises the possibility of malignancy.