Fever of unknown origin without increase of serum C-reactive protein in a patient with acute lymphoblastic leukemia/lymphoblastic lymphoma

Abstract

A 28-year-old Japanese man had complained of prolonged fever of unknown origin for 7 months. Because his pancytopenia was mild and serum C-reactive protein (CRP) level was negative, hematologic malignancy had not been suspected. After admission to our hospital, his serum lactate dehydrogenase (LDH) level gradually increased and bone marrow aspiration was performed. B lymphoblasts were detected by flow cytometric analysis, leading to a diagnosis of acute lymphoblastic leukemia/lymphoblastic lymphoma (ALL/LBL). Although no increase in serum CRP and slow progression of pancytopenia are rare in ALL/LBL, hematologic malignancy should be suspected in febrile patients with prolonged fever of unknown origin.