[Pyoderma gangrenosum].

GENERAL CHARACTERISTICS: Rare cause of cutaneous ulceration, pyoderma gangrenosum is among the group of neutrophilic dermatites characterized by the richness of the mature neutrophilic polynuclear dermal infiltrate. The primary lesion is a pustule sitting on an inflammatory base; extremely painful, it rapidly ulcerates. The lesion rapidly extends to more than 10 cm in diameter, has a regular, sharp border and a peripheral roll of flesh exhibiting purulent channels on the inside and a red granulous surface often covered with a pustular coating. Little is known of this disease. CONCOMITANT AFFECTIONS: In more than 50% of cases, pyoderma gangrenosum is associated with other diseases, which must be systematically searched for. These may be digestive, essentially inflammatory enterocolitis with frequent development of peristomal ulceration, rheumatismal affections notably rheumatoid arthritis, hematological affections (benign monoclonal gammapathy, chronic myeloid hemopathy). FROM A PARACLINICAL POINT OF VIEW: There are no specific examinations. A cutaneous biopsy should be performed in all cases, notably to eliminate other causes of ulceration. Since concomitant disease can be subsequently revealed, it is essential to renew the paraclinical investigations, even after the disease has healed. NO CODIFIED TREATMENT: Treatment of the cause, if it can be cured, may be sufficient to permit regression of the lesions. Local treatments to provoke budding and hence avoid surinfection are mandatory. In the progressive and extensive forms, systemic treatment, notably high dose corticosteroids, is indicated. Surgery, a priori, is excluded.