On atopic and idiopathic extensive pityriasis alba.

Letters must be signed by all authors, typewritten double spaced, and must not exceed two pages of text including references. Two copies of all letters should be submitted along with one copy on disk. Letters should not duplicate material submitted or published in other journals. Prepublication proofs will not be provided. To the Editor: We read with interest the description of extensive pityriasis alba (EPA) in a child with atopic dermatitis (AD) reported recently by Sandhu et al (1). In that article the main differences between classical pityriasis alba (PA) and EPA, a condition described by Zaynoun et al in 1983 in nine dark skinned young women from Lebanon (2) are discussed. Although the single skin lesions of EPA do not differ substantially from those of pityriasis alba, consistent differences are a widespread, symmetric involvement of the skin of the trunk by numerous, round, nonscaly, hypomelanotic patches without a preceding inflamma-tory phase and with long-lasting duration. Histologic examination shows a decrease of epidermal melanin; spongiosis is absent. Ultrastructural studies suggested that this hypopigmentation resulted primarily from a reduced number of active melanocytes and a decrease in the number and size of melanosomes. No atopy, associated pathologies, or familial occurrences were reported. In our opinion the term EPA is a misnomer. There is no clear evidence of a relationship between EPA and classical PA: not only the distribution of the skin lesions, but also the age of occurrence, the sex ratio (female preponderance), the lack of a preceding inflammatory phase, and the absence of spongiosis sharply differentiate the two conditions. In addition, PA usually presents with skin patches showing small amounts of overlying scale and elevated borders. Seasonal variation with exacerba-tion in the summer and the winter is common. Skin lesions are often located on the face, although involvement of the arms and shoulders sometimes occurs. Widespread lesions of classical PA can be observed in atopic dermatitis, but they should not be confused with the disorder described by Zaynoun et al (2). Current knowledge would lead us to suggest that EPA overlaps with another condition described by Guillet et al in 1988 as progressive and extensive hypomelanosis in persons of mixed racial background (3) and reported also as progressive and confluent hypomelanosis of the melano-dermic metis or Creole dyschromia (4–6). This is a primary, acquired hypopigmentation observed in females from 18 to 25 years of age of mixed ethnic origin and …