Pityriasis rubra pilaris (PRP) comprises a group of clinically similar papulosquamous dermatoses, the underlying pathogenesis of which is only just beginning to be unravelled. They initially present with erythematous hyperkeratotic perifollicular papules that tend to coalesce into plaques but may progress to erythroderma, particularly in adults. The distribution, age of onset and speed of onset differ markedly between patients and these differences have been used to classify PRP into a number of clinically distinct subtypes. Using candidate gene screening, investigators have identified heterozygous gene mutations in CARD14, an activator of nuclear factor κ light chain enhancer of activated B cell (NFκB) signalling, which is implicated in other inflammatory diseases. In addition to coverage of conventional therapies such as acitretin and methotrexate, the place of biological agents, in particular ustekinumab, in managing these disorders is discussed.

Keywords pityriasis rubra pilaris, CARD14