[A case of central nervous system relapse in acute promyelocytic leukemia].

A 70-year-old woman who have achieved complete remission (CR) of acute promyelocytic leukemia (APL) with all-trans retinoic acid and chemotherapy presented with abnormal sensation in the right lateral thigh and the bilateral legs. In addition, neurological examination revealed weakness of the left shoulder abduction, the right hand, and the bilateral lower limbs. Atypical promyelocytes were detected in the cerebrospinal fluid, in spite of normal finding in the peripheral blood smear. Magnetic resonance imaging showed gadolinium-enhanced multiple intradural/extramedullary lesions in the whole spine. Nerve conduction studies of the right limbs revealed sensorimotor conduction abnormalities, conspicuously in the posterior tibial and sural nerves. As a result, she was diagnosed as having intrathecal relapse of APL, associated with multiple mononeuropathy. The neurological symptoms were completely disappeared by intrathecal chemotherapy and whole-spine radiotherapy, suggesting that the neuropathy was possibly caused by meningeal infiltration affecting multiple spinal nerve roots. Since extramedullary or intrathecal relapse is extremely rare in APL compared with other types of leukemia, precise neurological evaluations and suitable treatment should be performed immediately, when APL patients with CR manifest some neurological symptoms.