Coxiella burnetii infection of left atrial thrombus mimicking an atrial myxoma.

Infection of intracardiac thrombi is extremely unusual. Coxiella burnetii is a well-recognized etiologic agent of negative-blood culture endocarditis and vascular graft infection. Herein we describe the first reported case, to our knowledge, of C. burnetii infection of a large left-sided intracardiac thrombus that was initially misdiagnosed as an atrial myxoma. Diagnosis was confirmed by direct immunofluorescence assay, electron microscopy, and C. burnetii-specific polymerase chain reaction analysis performed on tissue sections of the thrombus.