Idiopathic pyoderma gangrenosum and impaired lymphocyte function: failure of azathioprine and corticosteroid therapy

SUMMARY A 58‐year‐old man with chronic ‘idiopathic’ pyoderma gangrenosum, recurrent secondary staphylococcal infection, nail candidiasis, markedly impaired lymphocyte function and a serum blocking factor is described. Despite an initially favourable response to immunosuppressive therapy, the patient later relapsed whilst on high dose systemic corticosteroids and azathioprine. Immune function remains abnormal 3 years after cessation of azathioprine. Attempted immunostimulation with Corynebacterium parvum proved unsuccessful. A striking but transient increase in lymphocyte function followed parenteral iron therapy for an unexplained iron‐deficiency anaemia. Gradual reduction in prednisone dosage to 5 mg daily has coincided with a period of clinical resolution and modest improvement in lymphocyte reactivity. Prolonged immunosuppressive therapy may be inadvisable in chronic idiopathic pyoderma gangrenosum associated with defective cellular immunity.