Dermatosis papulosa nigra (DPN) is a benign condition first described by Castellani in 1925. It is a very common skin dermatosis that consists of multiple dark brown to black, smooth, dome-shaped papules mostly on the face, upper back, chest and neck of darkly pigmented individuals (Figure 16.1). While those affected are most commonly African American, reports of DPN have been described in Asians, Europeans, and Hispanics.
Multiple dark brown to black, smooth, dome-shaped papules on the right cheek
Pathogenesis is largely unknown, but many authors consider DPN to be a variant of seborrheic keratosis based on their similar histopathologic findings. DPN may be caused by a nevoid developmental defect of the pilosebaceous follicle and thus may be classified under the group of epithelial nevi.1
The incidence in study populations varies from 10% to 77%, with approximately 50% of patients reporting a family history of similar lesions.1,2 Darker individuals are affected most frequently with a 2:1 predominance in females. DPN appear after puberty and slowly increase in size and number with age with a peak incidence in the sixth decade,2 although there have been reports of patients as young as age three with the lesion.3
Despite the benign nature of these lesions, many patients seek out medical advice on management and treatment. The conventional treatment options include simple excision, cryosurgery, electrodessication, curettage, dermabrasion, and laser removal. While all these treatment modalities can be effective in treating DPN, there are potential side effects, such as scarring and dyspigmentation.
CLINICAL EXAMINATION AND PATIENT HISTORY
While DPN are considered completely benign, many patients are bothered by their cosmetic appearance or occasionally find them pruritic, and therefore come to the dermatologist's office seeking treatment. They are commonly referred to as “moles” and patients often want to be assured they are not malignant. Patient history usually consists of these lesions appearing after puberty and slowly increasing in size and number, which some patients feel gives them an older appearance. These papules may also become irritated by clothing, jewelry, or eyewear.
Physical examination reveals multiple, well-demarcated, firm, smooth, dome-shaped papules that vary from dark brown to black in color (Figures 16.2 and 16.3). They can also be pedunculated, resembling acrochordons.1 They usually measure between 1–5 mm in diameter and are mostly located on the malar area of the face but can also be on the neck, trunk, and other areas of the face1 (Figure 16.4). In a study of 93 patients, all affected patients had facial lesions with 40% having face and neck involvement and 29% with face, neck, and trunk lesions.2 Unless recently irritated, there is usually no evidence of scaling, crusting, or ulceration. Differential diagnosis includes ...