[Malignant lentigo]

Lentigo maligna (LM) is a premalignant skin alteration, which may progress to lentigo maligna melanoma (LMM). LM usually appears as a small dark brown spot in the head and neck region. Over some years it may gradually enlarge to palm size and the colour become more motley. Histologically many atypical melanocytes are seen in the basal layer of the epidermis and along the adnexal structures, as well as there being dermal elastosis and a lymphohistiocytic inflammatory infiltrate in the superficial dermis. Excision should be performed as soon as the diagnosis is made to avoid more extensive excision, transplantation and development into LMM later on. If transformation of LM into LMM occurs, often after many years, fast growth, increased pigmentation and sometimes a nodular formation are observed. Histologically, the atypical melanocytes have invaded the dermis.