Pityriasis amiantacea: clinical-dermatoscopic features and microscopy of hair tufts

Abstract

Pityriasis Amiantacea, also known as pseudotinea amiantacea, is a clinical syndrome which affects the scalp, having a reaction pattern reported to occur in several inflammatory dermatoses. The authors seek to establish the correlation between its clinical, dermoscopic and light microscopy features through the analysis of scale-encrusted hair tufts submitted to histological processing. Keywords: Dermatitis, seborrheic; Dermoscopy; Pityriasis; Psoriasis; Tinea Resumo: A pitiríase amiantácea, também chamada de pseudotínea amiantácea, é compreendida como uma síndrome clínica que acomete o couro cabeludo. Representa um padrão de reação a diversas dermatoses inflamatórias. Os autores procuram estabelecer a correlação entre características clínicas, dermatoscópicas e de microscopia ótica, através da análise do tufo de cabelos agregados pelas escamocrostas, submetido a processamento histológico.

The value of trichoscopy in the differential diagnosis of scalp lesions in pemphigus vulgaris and pemphigus foliaceus

“…Our data may indicate that hair casts in pemphigus are rather a sign of severe diffuse scaling (similar to Pityriasis amiantacea ) than a direct reflection of acantholysis. 36 …”

Dermoscopy as a useful supportive tool for the diagnosis of pityriasis amiantacea-like tinea capitis

“…), tinea capitis may display peculiar dermoscopic features such as “comma” hairs, “corkscrew” hairs, “zigzag” hairs, interrupted (Morse code-like) hairs, “elbow-shaped” hairs and “question mark” hairs [3–7]. Regarding the present instance, even though we observed dermoscopic findings that may be commonly seen in PA, i.e., diffuse white scaling and the characteristic compact white keratotic material adhering to a tuft of hair (asbestos-like scales) [10], dermoscopy turned out to be very helpful in suspecting tinea infection by showing the aforementioned “zigzag” and “question mark” hairs. In fact, although such features (or similar findings) may be rarely found in other hair disorders (e.g., “zigzag” hairs in trichorrhexis nodosa, alopecia areata and monilethrix, and “question mark” hairs in alopecia areata) [3–7], they are typically not visible in classic PA [10].…”

Development of pityriasis amiantacea after valproic acid therapy

“…Currently, evidence appears to indicate that PA is a prominent autoinflammatory response with possible participation of genetic and environmental factors. [13] We describe an extraordinary case of PA on a patient with seborrheic dermatitis (SD) who manifested after the onset of valproic acid.…”