CNS relapse in acute promyeloctyic leukemia.

A 42-year-old female was diagnosed with acute promyelocytic leukemia (APL) with a translocation of chromosomes 15 and 17 involving the PML and RARA genes. On presentation she met criteria for low-risk disease on the basis of platelet count (50 10/L) and WBC count (0.8 10/L). The patient achieved a complete molecular remission after induction chemotherapy with all-trans-retinoic acid (ATRA) and idarubicin (AIDA) and underwent consolidation chemotherapy per the risk-adapted Spanish Cooperative Group for Hematological Malignancies Treatment (PETHEMA) regimen, on completion of which she remained in molecular remission. She subsequently received maintenance therapy with oral ATRA, 6mercaptopurine, and methotrexate per the Cancer and Leukemia Group B C9710 protocol. Two weeks after completion of maintenance therapy, the patient had a bone marrow examination that demonstrated molecular relapse, on the basis of a positive bone marrow reverse transcriptase polymerase chain reaction (RT-PCR) for PMLRARA that was confirmed on repeat study 4 weeks later. Peripheral blood counts, bone marrow morphology, and cytogenetics were normal. The patient reachieved molecular remission after two 30-day cycles of arsenic trioxide (ATO) and underwent autologous peripheral blood stem-cell transplantation (SCT) for consolidation, with high-dose busulfan and cyclophosphamide conditioning. Five months after SCT, the patient presented with 1 week of right-sided headache worse with neck flexion, 3 days of intermittent visual loss in her right eye, and paresthesias of the right leg. Magnetic resonance image revealed diffuse leptomeningeal enhancement. Figure 1 shows an axial T1-weighted, gadolinium-enhanced image demonstrating regions of leptomeningeal enhancement (arrows). Cerebrospinal fluid (CSF) analysis revealed blast cells that were CD33 and CD13 positive and HLA-DR negative, and RT-PCR confirmed the presence of PML-RARA transcripts. Figure 2 shows a diffuse infiltrate of myeloblasts and promyelocytes within the CSF (Fig 2A). On high-power view (Fig 2B), several abnormal promyelocytes are noted, with intense azurophilic granules, bilobed nuclei, and dispersed chromatin. Auer rods, single as well as multiple, are present. Bone marrow analysis