Pyoderma gangrenosum--response to topical nitrogen mustard.

We report a 69-year-old caucasian male patient with long-standing pyoderma gangrenosum; the lesions preceded the appearance of an IgA monoclonal gammopathy by 2 years. A number of systemic treatments, including high dose steroids and immunosuppressive agents, were poorly tolerated and resulted in serious side-effects. The skin and haematological conditions, however, were kept under control for 2 years with regular plasmapheresis. Pyoderma gangrenosum recurred as vascular access became exhausted but new lesions healed completely with topical application of 20% nitrogen mustard.