A fever of unknown origin is often worked up with a bone marrow, but this test is not appropraite before a full workup failes to reveal other explanation of fever. A bone marrow aspiration and biopsy is not the appropriate tests for workup of fever that is not FUO. For example, the medically necessary approach to rule out a suspected lymphoma involves locating a lymph area that may be invovled by it. This test remains important in investigating fever of unknown origin, which, however, is by definition prolonged and unexplained after appropriate clincial and radiologic approaches. Bone marrow aspiration should not be used early or routinely to investigate fevers.
In one recent study looking at the role of this procedure in patients in India, where granulomatous diseases are more common than in the USA, 121 patients with pyrexia of unknown origin underwent both bone marrow aspiration and trephine biopsy as a part of diagnostic work-up. Bone marrow aspiration was diagnostic in only 16.5% of cases, which revealed leishmaniasis or pure red cell aplasia. Granulomas were infrequent in marrow aspiration smears, as only two cases (1.6%) showed ill defined epithelioid cell collections. Compared to this, trephine biopsy offered a diagnosis in 76% of the cases. Granulomas were a frequent finding in the trephine biopsy, being present in 70% of the cases included. Additional cases diagnosed on biopsy (over those diagnosed with aspiration smears) included lymphoma, tuberculosis, fungal infection, sarcoidosis and hypocellular marrow.
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