External auditory canal and middle ear relapse of acute promyelocytic leukemia treated with arsenic trioxide: case report and review of the literature.

Extramedullary involvement occurs infrequently in acute promyelocytic leukemia and is said to be more common after treatment with all-trans retinoic acid. We describe a 9-year-old girl who had an isolated external auditory canal and middle ear relapse after treatment with all-trans retinoic acid and chemotherapy. A patient with cytogenetically and molecularly confirmed acute promyelocytic leukemia developed isolated extramedullary relapse in the auditory canal and middle ear 4 years and 9 months after initial diagnosis, while in hematologic and molecular remission, successfully treated with arsenic trioxide alone.