Relapse in the external auditory canal of acute promyelocytic leukemia after treatment with all-trans retinoic acid.

A 54-year-old female was admitted to our hospital for gingival bleeding and was diagnosed as acute promyelocytic leukemia (APL). She received induction therapy according to the AML92 protocol of the Japan Adult Leukemia Study Group (JALSG) with all-trans retinoic acid (ATRA) plus chemotherapeutic agents. She achieved complete remission, but one year later had a relapse in her external auditory canal without leukemic cell in the bone marrow. Extramedullary disease is rare in APL. This case suggests the importance of careful observation for extramedullary relapse in patients who are treated with ATRA.