Pityriasis versicolor and Ichthyoses - Pityriases

Pityriasis versicolor

Definition

Pityriasis (bran-like) versicolour (varying in colour) is a chronic infection characterised by multiple macular patches varying in size and degree of brown pigmentation occurring on the trunk.

Aetiology

Caused by infection by the commensal yeast Pityrosporum orbiculare (also known as Malessezia furfur, Pityrosporum ovale and Malassezia ovalis). Infection results from conversion of the yeast to the mycelial or hyphal form, which may be triggered by heat and humidity and immunosuppression. The yeast releases carboxylic acids, which inhibit melanin production.

Clinical features

Lesions are superficial hypopigmented macules appearing light brown or salmon coloured with a fine scale. They are most seen commonly on the upper trunk and proximal limbs.

Management

Treated with topical antifungal agents for 2 weeks. Oral antifungals may be used for extensive disease. Recurrence is common, and frequent relapses may require prophylaxis with topical selenium sulfide or an oral conazole. The loss of colour in the skin may persist for several months after treatment.

Ichthyoses

Definition

The ichthyoses are disorders of keratinisation, which may or acquired characterised by a generalized  be congenital scaling of the skin due to hyperkeratosis (see Table 9.2).

Management

Topical emollients and bath additives are used to help avoid the dryness. Oral retinoids are used in the more severe forms.