2.A 48-year-old hematologic oncologist is receiving 7-day administration of cladribine (0.1 mg/kg/day by continuous intravenous infusion) for his recently diagnosed hairy cell leukemia. His fatigue and splenomegaly is already improved after day 4. On day 6, he develops fever of 101.1°F. He is hemodynamically stable and he complains of no specific symptoms. Examination is unremarkable. Chest x-ray is negative. CBC shows WBC 2,200/μL, absolute neutrophil count (ANC) 1,050/μL, hemoglobin 8.9 g/dL, and platelet 74,000/μL. Blood and urine cultures are pending. What is the most likely etiology of his fever?

A. Zoster reactivation

B. PCP pneumonia

C. Cladribine-induced fever

D. Neutropenic fever

E. Splenic infarction