Unexpected Priapism Secondary to Chronic Myeloid Leukemia in Chronic Phase
Introduction/Background/Significance: Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm driven by the BCR-ABL1 fusion gene with overproduction of granulocytes and typically associated with the Philadelphia chromosome or t(9;22). CML is further classified into phases including chronic, accelerated, and blast crisis. Despite marked leukocytosis or hyperleukocytosis (WBC >100 x103/μL), patients in chronic phase are usually asymptomatic. When leukocytosis becomes symptomatic, it is termed leukostasis, a high-mortality condition caused by microvascular obstruction from excess WBCs and can present with respiratory distress, neurologic deficits, and priapism due to impaired penile outflow. Leukostasis should raise the concern for accelerated and blast crisis in CML, the more aggressive forms of the disease, and is uncommonly seen in the generally asymptomatic chronic phase. We present a rare case of chronic phase CML presenting initially with priapism secondary to leukostasis.
Materials and Methods/Case Presentation/Objective: A 38-year-old male with no medical history presented with four hours of priapism following sexual activity. He denied medications, recreational substances, or trauma. He reported recent exertional dyspnea over the past two weeks, and he was tachycardic without hypoxia upon initial examination. Labs showed a WBC count of 364.6 x10^3/μL, hemoglobin of 7.0 g/dL, LDH of 1443 U/L, with the differential showing only 3% blasts and 3.6% basophils. Peripheral smear demonstrated neutrophilia, increased basophils and myelocytes, but only rare myeloid blasts (1%). Urology performed corporal aspiration and irrigation with improvement. He was admitted to the ICU for urgent initiation of leukapheresis and hydroxyurea to control leukostasis. Fluorescence in situ hybridization (FISH) confirmed BCR-ABL1 in 94% of cells on peripheral blood smear. Bone marrow biopsy revealed hypercellular marrow ( >95%) with myeloid hyperplasia and no increased blasts. Cytogenetics showed t(9;22) in 18/20 metaphases. No additional mutations were identified on myeloid next generation sequencing. With the diagnosis of chronic phase CML confirmed, he was started on dasatinib with excellent response and discharged after nine days.
Results/Description/Main Outcome Measures: Overall, this patient's presentation of priapism and dyspnea in the setting of hyperleukocytosis initially raised the concern for CML in the accelerated phase or blast crisis. However, the patient lacked the diagnostic criteria for a more progressive phase of the disease. His peripheral and bone marrow blast percentages were low, basophilia was minimal, and no additional cytogenetic abnormalities besides the Philadelphia chromosome were found. The clinical response to cytoreductive therapy further supported chronic phase disease. In summary, the case portrays an uncommon presentation of leukostasis in the chronic phase of CML, a syndrome that is more often an indicator of more aggressive disease.
Conclusions: This case of CML presenting with leukostasis in the chronic phase highlights the importance of recognizing leukostasis as not only a sign of the advanced phases of CML, but additionally as a rare manifestation of an early presentation of CML. The condition of leukostasis is still associated with high mortality and requires immediate identification and action to bridge the patient to definitive therapy, further emphasizing the importance of not overlooking marked leukocytosis, regardless of disease phase.
