Pyoderma gangrenosum is an idiopathic necrotizing condition of the skin.
The primary lesion is usually a pustule with a deeply violaceous rim. The central area becomes necrotic, producing a deep ulcer, with a broad violaceous rim and an overhanging edge. The ulcer expands peripherally. This lesion is very tender. Healing of ulcers occurs with scarring.
Another type of lesion is a red nodule, clinically and histologically resembling that seen in Sweet Syndrome.
Some lesions show Koebner's phenomenon.
There can be an associated fever and malaise.
Pyoderma gangrenosum has been reported in association with ulcerative colitis, Crohn's disease, collagen vascular disease and Sweet syndrome.
- Topical sodium cromoglycate