CNS-Isolated Blast Crisis in A Patient with Chronic Myeloid Leukemia on Dasatinib (P10-13.004)

Abstract

<h3>Objective:</h3> NA <h3>Background:</h3> Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by increased cellular proliferation of myeloid precursors and mature cells due to formation of the BCR-ABL proto-oncogene. Blast crisis is characterized as a rapid expansion of a population of myeloid or lymphoid blast cells and defined as &gt;20% blasts in bone marrow or blood. Extramedullary blast crises isolated to the central nervous system are extremely rare, limited to few case reports. <h3>Design/Methods:</h3> NA <h3>Results:</h3> We present a 57 year old male with history of CML since October 2020 on dasatinib 70mg daily who presented with complaints of daily occipital headaches for three months. Exam notable for persistent encephalopathy and unsteady gait. Peripheral serology was unrevealing, suggesting complete hematologic response to dasatinib. MRI brain revealed diffuse leptomeningeal enhancement, as well as small regions of parenchymal enhancement in left frontal lobe, right optic nerve, and lower lying tonsils to suggest early tonsillar herniation. Patient subsequently received left frontal open biopsy and CSF drainage. CSF analysis was unremarkable except for atypical cells. Biopsy of the leptomeninges revealed focal areas consistent with aggregation of myeloid blast cells. Peripheral blood RT-PCR showed BCR-ABL positivity in BCR-ABL1 subtype e13a2 (b2a2, p210) at 0.0788%, which is still consistent with major cytogenetic response to dasatinib. Patient was transferred to outside hospital for evaluation of hematopoietic stem cell transplant. <h3>Conclusions:</h3> Isolated CNS blast crises are rare, with a few cases in the hematological literature, reporting occurrence in patients on chronic imatinib or dasatinib therapy. This may be due to poor CNS penetration of these medications. Here, we demonstrate a patient that had complete hematologic response and major cytogenetic response to dasatinib systemically but with extensive CNS involvement. It is therefore important to have appropriate workup for neurological symptoms with patients with CML despite appearing in chronic phase of the hematological illness. <b>Disclosure:</b> Dr. Puccio has nothing to disclose. Dr. Rodriguez Lee has nothing to disclose. Dr. Song has nothing to disclose.