Blaschkoid melanotic cutaneous lupus erythematosus with “melanocytic nests”

Melanotic cutaneous lupus erythematosus (LE) is a newly described clinical variant of chronic cutaneous LE, presenting with localized or diffuse brownish or grayish macular and reticulated pigmentation in the absence of erythema, scaling, atrophy, scarring, or telangiectasia. The diagnosis is based upon histopathology, which demonstrates the characteristic features of LE with an interface vacuolar dermatitis with melanophages, and a superficial and deep, perivascular and periadnexal lymphocytic infiltrate with mucin deposition. Herein, we describe a case of a 61-year-old White male presenting with melanotic cutaneous LE with a blaschkoid distribution on his face in which the histopathological phenomenon of “true melanocytic nests” in the setting of a lichenoid pattern was seen. We want to highlight how nests of cellular aggregates at the dermoepidermal junction labeling with melanocytic markers may occur in the setting of an interface tissue reaction. This benign reactional pattern may mimic atypical melanocytic proliferations, especially on sun-damaged skin. Clinicopathological correlation and careful microscopic examination using a panel of multiple melanocytic markers is crucial for making an accurate final diagnosis. All the cases of melanotic cutaneous LE reported in the literature are also reviewed.