Characteristics of Hori naevus: a prospective analysis.

Background: Acquired, bilateral naevus of Ota-like macules or Hori naevus (HN) is a common dyschromia seen in Orientals. Other than the original report which documented the clinical spectrum in a group of 22 patients, there have not been many epidemiological reports of this condition.
Objectives: To evaluate the epidemiology and clinical characteristics of HN in Asian patients.
Methods: A prospective analysis of 161 patients with HN seen from June 2003 to June 2004 was performed.
Results: All 161 patients in the study were women. Patients were Chinese (n = 155), Eurasian (n = 4), Malay (n = 1) and Indian (n = 1). The median age at onset was 30 years. The malar region was the most frequently affected area. Discrete brown macules were the most common early presentation. Confluent slate-grey macules occurred later. Aggravating factors included sun exposure and pregnancy. Sixty-seven patients reported a positive family history.
Conclusions: We report our data on the largest series of HN in the literature so far. Predisposing factors in our study are Chinese race, female sex and positive family history. HN became progressively more confluent and grey over time, suggesting migration from the epidermis to the deeper dermis. More studies are needed to confirm the pathogenesis.