Oral communication, CS3 / C12

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

How to differenciate melasma from facial postinflammatory hyperpigmentation (PIH)?

BACKGROUND: The most common facial pigmentations are melasma and PIH. Melasma has a predilection for sun exposed area. In PIH the patches are characteristically limited to the site of the preceeding inflammation and have indistinct, feathered borders. According invasive techniques distinguished features have been described. In melasma there is an epidermal melanin deposition (non aggregated melanosomes) in all the layers including horny layer associated in some cases with dermal melanin deposition. In PIH the basement membrane is frequently disrupted and melanin falls into the dermis and resides within melanophages. OBJECTIVE: To develop a non invasive technique for the detection of melanin in the horny layer useful to differenciate melasma from PIH. METHOD, based on the detection of melanin in the horny layer: The adhesive coated surface of one slide is briefly pressed to the pigmentation with a rocking motion. If applied directly to human skin, the slide provides a specimen of a monolayer of thousands of cells. Staining of the melanin granules is achieved with Masson’s ammoniacal silver nitrate. Under oil immersion the number of melanin granules can be easily counted. In some horny cells large clusters of granules were noticed particularly in the center of the cells. RESULTS: In melasma, many isolated or aggregated melanin granules are observed in all the corneocytes whereas in PIH very rare granules are found in some corneocytes. CONCLUSION: It is very important to differenciate melasma from PIH because they have not the same prognosis and their management is quite different.

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