Fever of unknown origin (FUO) still remains a diagnostic challenge, while diagnosis may remain obscure for several weeks or months. The role of tissue biopsy is crucial in the diagnostic approach. We report a series of 130 consecutive patients with FUO who had undergone a bone marrow biopsy (BMB). Methods: Among 280 consecutive nonimmunocompromised patients hospitalized between 1995 and 2005 for a febrile illness of uncertain cause, lasting at least 3 weeks, with no diagnosis after an

more »

... e minimal diagnostic workup, 130 underwent BMB. Results: Overall, a specific diagnosis was achieved by BMB and histological examination in 31 cases (diagnostic yield, 23.7%). Three types of diseases were found: hematological malignant diseases in 25 cases, including 19 patients with malignant lymphoma, 4 with acute leukemia, 1 with hairy cell leukemia, and 1 with multiple myeloma; infectious diseases in 3 cases; systemic mastocytosis in 2 cases; and disseminated granulomatosis in 1 case. Thrombocytopenia (odds ratio, 4.9; 95% confidence interval, 1.04-9.30) and anemia (odds ratio, 3.24; 95% CI, 1.13-9.34) were the most reliable predictive factors regarding the usefulness of BMB. Bone marrow cultures had very limited value in our cohort. Finally, corticosteroid use did not seem to affect the yield of BMB. Conclusions: Bone marrow biopsy is a useful technique for the diagnosis of prolonged fever in immunocompetent patients. Thrombocytopenia and anemia seem to be correlated with the value of this test.