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

Abstract

The appearance of pigmented lesions in melanoma surgical scars is a frequent finding that in some instances may cause confusion with a melanoma persistence. Nevertheless, only a few papers have dealt with this subject in the dermatologic literature. The melanoma surgical scars of 60 consecutive patients were reviewed with special attention to the presence of pigmentation and its clinical characteristics. Simultaneously, the scars of 60 consecutive 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 non-pigmented scars, and processed for hematoxylin-eosin and immunohistochemistry. 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)). Clinically, three types of clinical pigmentation were observed: lentigine-like lesions; pigmented streaks in scars after direct closure; and diffuse pigmentation in grafts. Histologically, two patterns emerged: one with lentiginous epidermal hyperplasia, hyperpigmentation, and a normal or moderately increased number of melanocytes; and a second one characterized by melanocytic hyperplasia of a variable degree. The scar process itself, irrespective of the tumor excised, seems to be responsible for the pigmentation. We suggest the existence of an induction process of scar tissue acting on melanocytes of the overlying epidermis.

Regeneration of neural crest derivatives in the Xenopustadpole tail

“…These results are comparable to those previously obtained in the zebrafish, also showing that melanophores regenerate from unpigmented precursors [30,31,40]. It is also consistent with what is seen in wound healing of human skin, where the re-colonization of the epidermis involves the migration of melanocytes from the immediately adjacent epidermis [54]. …”

Sequence of melanocyte migration into human scar tissue

“…Botella-Estrada et al [3], in one of the very few histological reports on scars, described melanocytic pigmentation in excision scars of melanotic and non-melanotic skin tumours. These authors estimated that the scarring process itself seems to modulate the pigmentation, with the likely existence of a chemically-mediated induction process through which scar tissue acts on HMs of the local epidermis and directs their migration.…”

“…Because of their clear cytoplasm, melanocytes are readily identifiable by light microscopy as "clear cells" in haematoxylin & eosin (H&E) stained preparations. After trauma, HMs migrate from the immediately adjacent epidermis into the replenished epidermal defect and recolonise the epidermis [3,6].…”

The correlation of TRPM1 (Melastatin) mRNA expression with microphthalmia‐associated transcription factor (MITF) and other melanogenesis‐related proteins in normal and pathological skin, hair follicles and melanocytic nevi

“…Clinically, scars are paler than the surrounding epidermis, a trait that is not attributable to loss of melanocytes or a change in melanocyte function 27,31 . Rarely, scars can be pigmented 32 . These two disparate phenotypes may be secondary to stromal‐melanocyte interactions 33 .…”

“…It has been reported that melanocyte numbers do not differ between sexes, 24 but melanocyte counts/densities do change with age, 24,27,34,35 anatomic site, 24,32,36,37 sun exposure 25,34,35,38–40 and history and/or presence of an adjacent melanoma or melanocytic nevus 25,41,42 . Melanocyte LI for TRPM1 and melanogenesis‐related proteins were compared according to the above traits.…”