Endocarditis Caused by Zoonotic Pathogens and Antiphospholipid Syndrome Are Possible Differential Diagnoses: Authors' Reply.

The Authors Reply We would like to thank Dr. Fukuchi and colleagues for their interest in our recent case report in Internal Medicine regarding a patient with nonbacterial thrombotic endocarditis (NBTE) (1). They pointed out three important comments related to the differential diagnoses, including endocarditis caused by zoonotic pathogens and antiphospholipid syndrome. We also appreciate the opportunity to add some needed information about our patient.

As Dr. Fukuchi pointed out, endocarditis caused by zoonotic pathogens is important to consider in patients who repeatedly show negative blood cultures. As far as we could tell, the patient did not have any pets or opportunities to contact animals, including dairy farming activities.

As for second question, we also considered non-infective endocarditis and deep venous thrombosis in relation to collagen diseases. However, tests for anticardiolipin antibodies, anti-β2-glycoprotein I antibodies, and lupus anticoagulant were all negative. In addition, prolongation of the activated partial thromboplastin time was not observed at the time of admission.

Finally, we agree with Dr. Fukuchi's comment regarding cerebral hemorrhage. However, no cerebral aneurysm was noted in the pathological autopsy. The pathological autopsy revealed a cerebral infarction, and her diagnosis was hemorrhagic infarction. This diagnosis was also confirmed by CT. Therefore, we finally diagnosed NBTE due to malignancy.

The authors state that they have no Conflict of Interest (COI).