Melanotic pigmentation in excision scars of melanocytic and non-melanocytic skin tumors

The appearance of pigmented lesions in melanoma surgical scars is a frequen t finding that in some instances may cause confusion with a melanoma persis tence. Nevertheless, only a few papers have dealt with this subject in the dermatologic literature. The melanoma surgical scars of 60 consecutive pati ents were reviewed with special attention to the presence of pigmentation a nd its clinical characteristics. Simultaneously, the scars of 60 consecutiv e patients who had been subjected to excision of a non-melanoma skin tumor were also studied. Biopsies were performed in representative clinical cases of pigmented lesions arising on the scars of both groups, as well as in no n-pigmented scars, and processed for hematoxylin-eosin and immunohistochemi stry. Pigmented lesions were present in a similar percentage in both groups (30% in melanoma scars (18/60) and 25% in non-melanoma scars (15/60)). Cli nically, three types of clinical pigmentation were observed: lentigine-like lesions; pigmented streaks in scars after direct closure; and diffuse pigm entation in grafts. Histologically, two patterns emerged: one with lentigin ous epidermal hyperplasia, hyperpigmentation, and a normal or moderately in creased number of melanocytes; and a second one characterized by melanocyti c hyperplasia of a variable degree. The scar process itself, irrespective o f the tumor excised, seems to be responsible for the pigmentation. We sugge st the existence of an induction process of scar tissue acting on melanocyt es of the overlying epidermis.