Pustular psoriasis elicited by streptococcal antigen and localized to the sweat pore

A woman, aged 39 years, presented with a localized, painful, pustular eruption of the neck, scalp, and finger of five years' duration. A diagnosis of pustular psoriasis was made clinically and histologically. It was possible to reproduce the disease by the intradermal injection of killed Group A streptococcal organisms. The induced pustules, as well as those appearing clinically, were intraepidermal and indistinguishable from the Kogoj spongiform abscess, and on serial sectioning showed a distinctive localization to the acryosyringium. Immunosuppressant as well as antistreptococcal therapy in the form of cyclophosphamide and clindamycin was of help. The process is classified as a nonvasculitic pustular bacterid, and as a prototype for antigen localization of lesions to the occluded epidermal sweat duct unit.