Dermatosis papulosa nigra in Dakar, Senegal

Dermatosis papulosa nigra (DPN) is a benign epithelial tumour, common in the black population. It is a special topographic form of ethnic seborrheic keratosis, which is more common in the white population. Its benign character has meant that very few studies have been performed. In Senegal, no investigation has been carried out to date.

To determine the epidemiologic and semiological characteristics of DPN, and the aesthetic results of DPN exeresis.

A prospective study was carried out over a period of 6 months (November 2005 to April 2006) at the Dermatology Department, Le Dantec CHU, Dakar, Senegal. The diagnosis of DPN was clinical. If desired, exeresis of the lesions by fine-needle or fine-scissor electrosurgery was carried out, and the results were evaluated over a period of 6 weeks.

Thirty patients were evaluated: 21 women and nine men. The average age was 39.8 years (range, 25-70 years). A family predisposition was found in 93.3% of cases. The average age of onset of the lesions was 22 years, with a progressive increase in size and number. The lesions appeared initially on the face and then spread to all photoexposed areas. The lesions were profuse, numbering between 50 and 100 in 66.6% of cases, and coalesced to form plaques in 26.6%. In other cases, the lesions were papular, pediculate, or wide-based brown to deep black in colour, and with a keratotic appearance. Eight of the 21 women practiced artificial depigmentation and presented with profuse lesions. Aesthetic problems were found in 60% of patients. When performed, exeresis was satisfactory without scarring in 60% of cases at day 45. Hypochromic scars persisted in four patients who practiced artificial depigmentation and in one who had been treated with carbon dioxide snow.

This study on 30 cases of DPN is the first in Senegal. The classic female predominance, family predisposition, and photodistribution of the lesions were found. The lesions were profuse, with a background of artificial depigmentation. This suggests that the sun may be an etiopathogenic factor. Aesthetic problems are an indication for ablation of the lesions using a method that minimises the risk of scarring. Artificial depigmentation may cause delayed healing and dyschromic scars, as may the application of carbon dioxide snow.