[Sweet syndrome. Acute neutrophilic dermatosis in multiple myeloma].

A 64-year-old woman complained of reddish plaques that had suddenly appeared on her upper arms and trunk. Histological investigation revealed perivascular distribution of a neutrophilic infiltrate in the upper and mid-dermis; direct immunofluorescence showed deposits of C3 and fibrin in and around the vessels. Laboratory values in the blood, X-ray of the head and fine-needle biopsy of the hip showed the typical pattern of multiple myeloma. After chemotherapy the dermatological lesions improved rapidly, and the plasmocytoma reached remission stage. The diagnosis of Sweet's syndrome was established on the basis of the clinical and histological changes and the improvement observed after steroid therapy. The coincidence with plasmocytoma confirms the interpretation of Sweet disease as a paraneoplastic syndrome.