Pseudoleukoderm L81.5

Not uniformly used term for circumscribed, light colorations of the skin, which stand out as a "negative imprint" from normal or darker skin.

Pathogenetically, there is (in contrast to vitiligo) no reduced melanin content or no malfunction of the melanocytes (the white colorations in pityriasis versicolor are therefore not pseudoleucoderms but real leucoderms), but a simple color contrast phenomenon. Clinical examples are:

• Pseudoleukoderma atopicum(Pityriasis alba)
• Pseudoleukoderma psoriaticum (among others dithranol effect)

The term "pseudoleukoderm" is sometimes used for skin colorations whose light coloration is caused by a reduced blood flow, e.g. pseudoleukoderma angiospasticum or nevus anaemicus.

• Pseudoleukoderma angiospasticum (after exposure to cold or emotional stress)
• Pseudoleukoderma atopicum (Pityriasis alba)
• Pseudoleukoderma psoriaticum (e.g. development under cignolin/dithranol therapy)
• Mycosis fungoides ( Nappes claires)
• Erythroderma(Nappes claires)
• Pityriasis rubra pilaris (sharply defined, white patches of unaffected skin/nappesclaires-diagnostic sign)
• Nevus anaemicus (functional malformation of the capillaries; negative friction test - no redness after rubbing)

1. Minder E (2012)Drug-induced pseudoleucoderma: a commentary. Acta Derm Venereol 92:220