[Cutaneous malacoplakia in a patient with psoriasis vulgaris].

A 58 year old patient suffering from psoriasis vulgaris had typical erythematous, scaly plaques for 20 years. In addition, an erosive, therapy-resistant plaque was found in the perianal region. A biopsy was taken to exclude malignancy; it showed intracytoplasmic Michaelis-Gutmann-bodies as a marker for malakoplakia, which rarely occurs in the skin. In further electron microscopic investigation, intracytoplasmatic bacteria could be demonstrated. An underlying malignancy or chronic renal insufficiency with immunosuppression were not found in this patient; both are often associated with malakoplakia.