Is melanocyte density our last hope? Comparison of histologic features of photodamaged skin and melanoma in situ after staged surgical excision with concurrent scouting biopsies.

Differentiating melanocytic hyperplasia (MH) on photodamaged skin from junctional lentiginous melanocytic proliferations (JLMP), early evolving melanoma in situ (MIS), or the periphery of a lesion of MIS on staged excision can be challenging. Although previous cross-sectional studies have elucidated important criteria for distinguishing MH on photodamaged skin from more concerning lesions, this study highlights a technique to treat JLMP and MIS with staged mapped excision and baseline scouting biopsies of adjacent nonlesional photodamaged skin to assist in determination of surgical margin clearance. Additionally, we compare the lesional and photodamaged control biopsies from the same patient to evaluate relevant histologic criteria that may be used to distinguish MH in photodamaged skin from JLMP/MIS, while minimizing confounding factors. There was a statistically significant difference (P ≤ 0.05) found for melanocyte density, irregular melanocyte distribution, melanocyte clustering, follicular infundibulum involvement, and nesting. However, criteria such as nesting, epithelioid cells and melanocyte clustering were seen in both photodamaged skin and MIS. These findings underscore the fact that histologic features of photodamaged skin can overlap with the histopathological features of MIS. Of all of the criteria evaluated, melanocytic density was the most objective histologic criterion and did not show overlap between the sun-damaged and JLMP/MIS groups.