Dermatosis Papulosa Nigra

BACKGROUND

Dermatosis papulosa nigra (DPN) is a condition in which numerous brown stuck-on appearing papules are found on the malar cheeks and temples and are considered to be a subtype of seborrheic keratosis (SK). These lesions are found commonly in patients of African descent but can also be seen in other ethnicities who have Fitzpatrick phototype III and greater. Unlike typical SKs, DPN often develop earlier in life and are more common in women than in men. Treatment of DPN involves destruction via methods similar to those utilized for typical SKs, but extreme care must be taken to avoid dyspigmentation and scarring.

PRESENTATION

Patients typically present with multiple asymptomatic, small, dark brown or black papules on the malar cheeks and temples, which are occasionally pedunculated or verrucous.

DIAGNOSIS

Clinical Diagnosis

DPN presents as multiple benign, small, ˜1 to 4 mm soft brown to black papules on the head and neck; they are usually most concentrated on the upper cheeks, temples, and forehead of African American patients. The lesions are generally asymptomatic, and patients often have a history of other family members with similar DPN papules. Although they usually begin in adolescence or young adulthood, and grow more numerous during the aging process, some patients have experienced early onset.¹

Histopathology

Histology of DPN is identical to that of SKs and demonstrates acanthosis, variable hyperkeratosis, and occasionally pseudo horn cyst formation.²

PATHOGENESIS

DPN is considered a variant of SK, and recent investigation into the molecular alterations of DPN lesions shows they can harbor FGFR3 mutations.³

TREATMENT

The treatment approach to DPN is mostly similar to that of SK, with cryotherapy, curettage, electrosurgery, and shave excision all being potentially effective surgical therapies (Algorithm 11.4.1). Many types of lasers have been utilized for DPN, including the 532-nm diode, 585-nm pulsed dye, 1064-nm Nd:YAG, KTP, 1550-nm erbium-doped

Fraxel, and CO₂.¹,⁴ In a small 10-patient study comparing pulsed dye laser with curettage and electrodessication, it was found that the 3 modalities had no significant difference in patient outcome—all three provided “good” results with mean clearance ranging from 88% to 96%.⁵ The most common adverse event observed in this study was skin hyperpigmentation. The authors note, however, the hyperpigmentation resolved over 6 months with or without hydroquinone therapy. There are no reports of topical hydrogen peroxide 40% use in DPN.