Dermatosis papulosa nigra (DPN) is a benign cutaneous condition common among blacks. It is usually characterized by multiple, small, hyperpigmented, asymptomatic papules on the face of adult blacks. Histologically, dermatosis papulosa nigra resembles seborrheic keratoses. The condition may be cosmetically undesirable to some patients. See the image below.
 View Image | Dermatosis papulosa nigra. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/lesions/dpn2.jpg). |
The pathophysiology of dermatosis papulosa nigra is not known. The occasional positive family history may suggest a genetic propensity.
Whereas earlier US studies revealed a 10% frequency in adult blacks, more recent data suggest a frequency of approximately 35% in this population. Data pertaining to the international frequency of dermatosis papulosa nigra are insufficient.
Dermatosis papulosa nigra affects up to 35% of the African American population.[1] Blacks with a fair complexion have the lowest frequency of involvement.[2] Dermatosis papulosa nigra also occurs among Asians, although the exact incidence is unknown.
Females are affected more frequently than males.[2]
Dermatosis papulosa nigra usually begins in adolescence and is rare in persons younger than 7 years.[3] The incidence of dermatosis papulosa nigra, as well as the number and size of individual lesions, increases with age.
The prognosis for patients with dermatosis papulosa nigra is excellent since it is not a premalignant condition nor is it associated with any underlying systemic disease. However, lesions of dermatosis papulosa nigra show no tendency to regress spontaneously, and they gradually may increase in number and size with age.
Lesions usually begin during puberty. They tend to increase steadily in number and size as the individual ages.
Dermatosis papulosa nigra is characterized by multiple, firm, smooth, dark brown to black, flattened papules that measure 1-5 mm in diameter. Lesions occur mainly on the malar area of the face and the forehead, although they also may be found on the neck, upper back, and chest. A small percentage of patients have similar lesions on the upper trunk. Scaling, crusting, and ulceration do not occur.
Dermatosis papulosa nigra is likely to be genetically determined, with 40-54% of patients having a family history of involvement. Dermatosis papulosa nigra is believed to be caused by a nevoid developmental defect of the pilosebaceous follicle. Hairston et al have suggested that dermatosis papulosa nigra should be classified within the group of epithelial nevi.[4]
Lesions of dermatosis papulosa nigra have the histologic appearance of seborrheic keratoses; they display hyperkeratosis, irregular acanthosis, keratin-filled invaginations of the epidermis (horn cysts), and marked hyperpigmentation of the basal layer. Although most lesions are of the acanthotic type and show thick interwoven tracts of epidermal cells, they may have a reticulated pattern in which the tracts consist of a double row of basaloid cells.
No treatment generally is indicated for dermatosis papulosa nigra unless lesions are cosmetically undesirable. Aggressive therapeutic modalities have been complicated by postoperative hyperpigmentation or hypopigmentation or scarring. Keloid formation is a potential complication. Therefore, conservative treatment is advisable.
Abrasive curettage with or without anesthesia,[5] superficial liquid nitrogen cryotherapy, and electrodesiccation followed by curettage have been shown to be effective. Laser therapy has also been reported.[6, 7, 8] Both EMLA (topical lidocaine/prilocaine cream) and LMX (topical lidocaine cream) creams are effective for providing topical anesthesia.[9] Use caution with all therapies to minimize the depth of treatment.
Dermatosis papulosa nigra. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/lesions/dpn2.jpg).
Dermatosis papulosa nigra. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/lesions/dpn2.jpg).
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