Indexed on: 16 Feb '07Published on: 16 Feb '07Published in: Dermatologic Surgery
The determination of clear margins during Mohs surgery for melanoma in situ arising on sun-damaged skin is often made difficult by the presence of background atypical melanocytic hyperplasia.To determine the density and distribution patterns of melanocytes adjacent to melanoma and nonmelanoma skin cancers.180 skin specimens obtained during the routine repair of defects resulting from the removal of melanoma and nonmelanoma skin cancers were analyzed using H and E-stained permanent sections to determine the quantity and distribution of epidermal melanocytes.The mean melanocyte density was 7.97 melanocytes per 1 mm of epidermis (SD,+/-6.7). Contiguous melanocytes were found in 30 (16.7%), atypical melanocytes were observed in 8 (4.4%), and follicular extension of melanocytes was observed in 11 (6.1%) of the specimens. These features were significantly associated with higher melanocyte densities (p< .001) and were more commonly observed in specimens from patients with melanoma.There is a high degree of variability in melanocyte densities seen adjacent to melanoma and nonmelanoma skin cancers. Contiguous melanocytes, atypical melanocytes, and follicular melanocytes can be seen in the sun-damaged skin surrounding both melanoma and nonmelanoma skin cancers, but especially with melanoma. Because some of the features of melanoma in situ can be seen in chronically sun-damaged skin, the Mohs surgeon should be cautious when assessing the margins for melanoma in this setting.