Abstract
INTRODUCTION: This case report is presented to improve our understanding of the atypical immunophenotype of hairy cell leukemia. PATIENT CONCERNS: A 58-year-old woman presented to our department with fatigue for >10 days. DIAGNOSIS: The patient was diagnosed with an increased proportion of abnormal lymphocytes in peripheral blood and bone marrow smear, positive for CD11c, CD19, CD20, CD22, CD25, CD123, CD200, and Kappa, partial expression of CD23, but no expression of CD103, positive for BRAF V600E mutation. INTERVENTIONS AND OUTCOMES: Cladribine combined with rituximab achieved complete remission of minor residual disease negativity. CONCLUSION: Hairy cell leukemia is rare, and the diagnosis and differential diagnosis should be made by combining the patient's medical history, clinical manifestations, immunophenotype, gene detection, and other means. Purine nucleoside analogs are the first-line treatments.