Psoriatic Plaques in Macaca fascicularis

An adult male cynomolgus monkey (Macaca fascicularis) developed erythematous plaques with adherent white scales on the skin. Microscopically, the epidermis had regular acanthosis with marked parakeratosis, focal absence of stratum granulosum, and spongiform pustules and Munro-like microabscesses. These histologic findings were suggestive of psoriasis vulgaris.