Unusual aspects of acute Q fever-associated hepatitis.

We describe a 37-year-old farmer with a 3-week history of fevers and hepatitis, in whom Q fever was diagnosed. The diagnosis was based on the findings of characteristic "ring" granulomas on a bone marrow biopsy specimen and confirmed by complement-fixation antibody tests to Coxiella burnetii. Unusual aspects of this case included (1) relatively low complement-fixation antibody titers, (2) prolonged prothrombin time, (3) false-positive results of a serologic test for the human immunodeficiency virus (HIV), and (4) ring granulomas that progressed to atypical granulomas in biopsy specimens.