Pityriasis amiantacea: clinical-dermatoscopic features and microscopy of hair tufts – Revista Anais Brasileiros de Dermatologia

Pityriasis Amiantacea (PA), also called pseudotinea amiantacea, is regarded as a clinical syndrome affecting the scalp. It appears to have a reaction pattern to various inflammatory dermatoses in this particular location. Among the diseases listed as possible causes, seborrheic dermatitis is, according to some authors, the most frequent, followed by psoriasis, superficial pyogenic or fungal infections, lichen planus, lichen simplex chronicus, pityriasis rubra pilaris and atopic dermatitis. The mechanism of formation of the scales characteristic of this syndrome is however still unknown. 1

PA was described by Alibert in 1832 as “shiny silvery scales, similar to mica (a mineral), which adhere to each other and surrounding hair shafts like the wax around the wick of a candle. They resemble the thin scales surrounding the small feathers of young birds, known to naturalists as ‘asbestos’ or ‘asbestos-like’ scales.” Asbestos (from the Greek , meaning indestructible, immortal, unquenchable), also known as amianth (Greek = pure, free from dirt, unsullied) is a generic name for various fibrous metamorphic minerals found in nature and used in a number of commercial products. The material consists of extremely thin, long bundles of fibers, easily separable from each other with a tendency to produce very small powdery particles