LAUSR

DEAR EDITOR, This image illustrates the vertical cutaneous invasion of an early-stage melanoma tumour. Human melanoma cells were identified by immunofluorescent staining of Melan-A, a marker of melanocytic lineage (red), within the cutaneous microenvironment. These are invading from the epidermis – highlighted by immunofluorescent staining for cytokeratin 14 (white) – into the dermis (nuclei stained with 4ʹ,6-diamidino-2-phenylindole, blue). Immunofluorescent staining of type IV collagen (green), a basement membrane marker, is evident below the basal-layer keratinocytes of intact epidermis, but is disrupted in areas of skin adjacent to melanoma, indicating its breakdown by invading melanoma cells.