NEUTROPHILIC DERMATOSES - PYODERMA-GANGRENOSUM AND SWEETS-SYNDROME

Pyoderma gangrenosum and Sweet's syndrome are classified as neutrophil ic dermatoses as they exhibit intense dermal inflammatory infiltrates composed of neutrophils with little evidence of a primary vasculitis. They share several characteristics and respond to immunosuppressives. Aetiology is felt to represent a manifestation of altered immunologic reactivity. Patients with both conditions concurrently have been descr ibed. Diagnosis is based on clinical and histopathological findings. H owever, clinically the typical forms of the two conditions are quite d istinct: pyoderma showing cutaneous ulceration with a purple undermine d border and Sweet's syndrome having tender, erythematous, nonulcerate d plaques and nodules. Approximately 50% of cases of pyoderma are asso ciated with a specific systemic disorder. These include inflammatory b owel disease, rheumatoid arthritis, non-Hodgkin's lymphoma and myelopr oliferative disorders. Many associations with Sweet's have been descri bed, acute myeloid leukaemia, myeloma and adenocarcinomas, and haemato logical malignancy. There is overlap between the two conditions with l esions categorised as Sweet's syndrome being clinically more character istic of atypical pyoderma and vice versa. We believe that pyoderma an d Sweet's syndrome represent a continuum of spectrum of disease. The r eason for the clinical differences between the conditions is unclear a nd merits further investigation but may be explained by varying levels of intensity and extent of the inflammatory process. This review will describe the pathogenesis, clinical features, diagnosis, associations and treatment of the two conditions.