Upon examination, a 40-year-old man was found to have fever, weight loss, a
nd malaise. A blood culture was positive for Streptococcus mutans. Under th
e suspicion of endocarditis, he was treated with penicillin. Echocardiograp
hy revealed a large tumor in the left atrium. After 6 weeks of penicillin t
reatment, he was transferred to our hospital for excision of the tumor. Pat
hology revealed a myxoma with fibrin deposits, bacterial colonization, and
massive infiltration with neutrophils.