Dermatosis papulosa nigra, first described by Aldo Castellani (1874-1971) >90 years ago, has since been presumed to be a variant of seborrheic keratosis, according to a recent review. However, despite their morphologic similarities, both macroscopically and microscopically, key differences have yet to be explained. These lesions also exhibit different demographics, with dermatosis papulosa nigra having a predilection for dark-skinned individuals and a female predominance. No studies to date have investigated this, but studies assessing the mechanisms of similar dermatologic conditions may yield significant clues. The additional impact of environmental factors may also be important, but much controversy exists.
Metin SA, Lee BW, Lambert WC, Parish LC. Dermatosis papulosa nigra: A clinically and histopathologically distinct entity. Clin Dermatol. 2017;35(5):491-496. doi:10.1016/j.clindermatol.2017.06.001.
Dermatosis papulosa nigra (DPN) is the condition of which dermatologists are very familiar. While my patients often refer to these as facial “moles,” I explain to them the true nature of these lesions. As the article points out, there are morphologic similarities, both clinically and microscopically, between this condition and seborrheic keratoses. Therefore, clinicians have always considered DPN a variant of seborrheic keratosis. The authors point out, however, that there are major differences between these conditions, including an increased incidence in darker-skinned individuals and a predominance of female patients. With an increased attention to the area of seborrheic keratosis, future studies will hopefully address this question. —Jeffrey M. Weinberg, MD