Progressive macular hypomelanosis: an epidemiological study and therapeutic response to phototherapy

Progressive macular hypomelanosis is a common dermatosis in various continents. Its cause is unknown and proposed treatments have had little effect.

To determine epidemiological aspects of progressive macular hypomelanosis in patients referred to a phototherapy clinic between 1997 and 2008 and to evaluate therapeutic response to PUVA (psoralen + UVA) photochemotherapy or narrowband UVB phototherapy.

Eighty-four patients with progressive macular hypomelanosis were evaluated. After 16 phototherapy sessions, therapeutic response was classified as: unchanged, slightly improved (<50% of repigmentation), moderately improved (50-79% of repigmentation), much improved (80-99%) or cured (100%). After a minimum of three months, patients whose response was classified as cured or much improved were contacted by telephone to evaluate the persistence of the therapeutic response.

Most of the patients were women (79%) and white (85%). Age at onset of progressive macular hypomelanosis ranged from 13 to 36 years. PUVA was prescribed for 27 patients and narrowband UVB phototherapy for 57. No significant difference was found between the outcomes obtained with PUVA and those obtained with narrowband UVB phototherapy (Fisher's exact test; p<0.05). The majority of patients (81%) had 50% or more repigmentation, with 65% being classified as cured or much improved. Nevertheless, there was a recurrence of the lesions in 72% of patients.

The fact that no patients were over 40 years of age suggests that progressive macular hypomelanosis is a self-limiting disease. Both PUVA and narrowband UVB are effective therapeutic options; however, they do not prevent recurrence of the disease.