White lines

White lines represent collagen in the dermis. They are seen in BCCs but also in some thicker nodular melanomas particularly the amelanotic kind and the peculiar desmoplastic variant.They are best seen using a polarising dermatoscope where you see best deeper into the lesion. The white lines usually have to be broad to make them significant of melanoma.

Desmoplastic melanomas can be the pink fibrotic type shown above with just white lines, plus a pink vascular area without specific vessels and a hint of pigmentation. As such they are difficult to diagnose and look scar like. The other type underlies a lentigo maligna pattern on the skin surface in a severely sun damaged individual and are even more difficult to diagnose but the skin may feel firm underneath. Do not do a shave biopsy in the latter situation or you may miss the desmoplastic elements deeper down.

 White lines reticular usually indicate fibroplasia of the papillary dermis, a finding that may be found in early melanoma and in so called "dysplastic nevi" (Clark nevus). This is the same as the term negative network seen in some melanomas.