Extramedullary relapse in lumbar spine of patient with acute promyelocytic leukemia after remission for 16 years: a case report and literature review.

Acute promyelocytic leukemia (APL) is a common myeloid leukemia. At the newly diagnosed stage, it can be fatal because of the serious complication-disseminated intravascular coagulation. With the advent and early application of all-trans retinoic acid, most APL patients can achieve a long-term survival, and only a minority of patients will develop extramedullary relapse after remission. The most common site of extramedullary relapse is central nervous system, while other sites are relatively rare. Here, we report a particularly rare APL patient who experienced extramedullary relapse with lumbar spine as the isolated site after a rather long time of remission for 16 years. At the time of relapse, the main clinical manifestations of the patient are obvious low back pain, weakness in lower limbs and limitation of activity. After treatment of local radiotherapy combined with ATRA and arsenic trioxide, the patient achieved and maintained a second complete remission by now.