Histologic features are not pathognomonic, but are useful to rule out other possible papulosquamous and erythrodermic disorders. The presence of acantholysis, hypergranulosis, follicular plugging and the absence of dilated capillaries and epidermal pustulation may help distinguish PRP from psoriasis. Features on electron microscopy include a decreased number of keratin filaments and desmosomes, enlarged intercellular spaces, parakeratosis with lipid-like vacuoles, large numbers of lamellar granules and a focal split in the basal lamina at the dermal epidermal junction. Topical corticosteroids may provide some patient comfort, but are believed to have little long-term therapeutic effect. Calcipotriol is a vitamin D analogue that has been used in the topical treatment of psoriasis.
Emollients reduce fissuring and dryness, providing some patient comfort.
Petroleum jelly or one of the many proprietary emollients may be used. The goals of pharmacotherapy are to reduce morbidity and prevent complications. A study by Borok in 1990 suggests that etretinate may be superior to isotretinoin. Since that time, etretinate has been taken off of the market due to its prolonged half-life and risk of teratogenicity. It has been replaced by acitretin, which still has risks of teratogenicity, but a much shorter half-life.