Patients with acquired immunodeficiency syndrome frequently develop fever and other nonspecific symptoms that elude diagnosis despite laboratory tests and imaging studies. In the general population, bone marrow biopsy is a safe and useful diagnostic test for investigating fever of unknown origin. Benito and associates studied the role of bone marrow biopsy in patients with human immunodeficiency virus (HIV) infection and fever of unknown origin.

Bone marrow biopsy was performed in 123 consecutive patients with 137 episodes of fever that persisted for 10 or more days. Biopsy was performed after patients had been hospitalized for one week. One or more AIDS-defining conditions were present in 113 (91.9 percent) of the patients before evaluation of fever began.

A specific etiology of fever of unknown origin was identified in 52 (38 percent) of the 137 episodes of fever by means of bone marrow culture and/or pathologic examination. Pathologic examination of the bone marrow alone led to diagnosis of a specific condition in 43 episodes of fever of unknown origin, representing 31.4 percent of all episodes.

Three types of disease were diagnosed by bone marrow biopsy: mycobacterial infection (36 patients), non-Hodgkin's lymphoma (12 patients) and visceral leishmaniasis (four patients). Bone marrow culture was more sensitive than microscopic examination in the diagnosis of mycobacterial infection. Tuberculosis was found in 18 patients and was confirmed by culture in 17 patients (10 from culture of bone marrow, three from blood, three from sputum and one from stool).

Mycobacterium avium–intracellulare complex (MAC) infection was diagnosed in 14 patients. The authors note that bone marrow biopsy was not sensitive for the diagnosis of MAC; more than one third of these patients had only nonspecific cytologic abnormalities. Bone marrow cultures were positive for organisms in five patients in whom the pathologic study was not diagnostic. All of the patients with MAC infection diagnosed by bone marrow examination subsequently had positive blood cultures in less than two weeks. In all 12 patients with non-Hodgkin's lymphoma, bone marrow biopsy was the hallmark of the presence of the tumor.

The authors conclude that bone marrow biopsy is a useful procedure for identifying the etiology of fever of unknown origin in patients with HIV disease, particularly in those who live in areas where tuberculosis and leishmaniasis are prevalent. Bone marrow biopsy is also useful in the diagnosis of extranodal non-Hodgkin's lymphoma when mass lesions are not accessible. In the diagnosis of MAC infection, bone marrow biopsy is no more valuable than blood culture.