A 66-year-old woman presented after an episode of accidental trauma with a painful ulcer on her scalp which rapidly enlarged in size, accompanied by central necrosis and undermining ulceration. The patient's past history was negative for underlying systemic disease, although she had had a similar post-traumatic intractable leg ulcer 3 years prior, which was unresponsive to surgical management but successfully treated with systemic steroids. A biopsied specimen from the scalp showed marked neutrophilic infiltrates in the dermis, compatible with a diagnosis of pyoderma gangrenosum (PG). The large ulcerative lesion responded very well to oral steroid therapy, showing rapid epithelialization. Serum levels of granulocyte colony-stimulating factor and interleukin-6 were significantly elevated prior to treatment, with decrease to normal levels after treatment. Serum tumor necrosis factor (TNF)-α and granulocyte macrophage colony-stimulating factor levels were within normal limits. The significance and pathogenic role of cytokine burst in PG is reviewed and discussed.