All- trans-retinoic acid-induced erythema nodosum in patients with acute promyelocytic leukemia.

Erythema nodosum associated with all- trans-retinoic acid (ATRA) for acute promyelocytic leukemia (APL) is very rare. We describe four patients with classic APL who developed erythema nodosum during ATRA therapy. Fever and subsequent multiple painful erythematous nodules over extremities developed on D11, D16, D17, and D19, respectively, after ATRA therapy. The skin biopsy taken from each patient was consistent with erythema nodosum. All patients received short course of steroids. Fever subsided rapidly and the skin lesions regressed completely. All patients achieved complete remission without withdrawal of ATRA. ATRA seemed to be the most possible etiology of erythema nodosum in our patients. Short-term use of steroid is very effective in ATRA-induced erythema nodosum.