Nonbacterial thrombotic
endocarditis (NBTE) is a rare condition; sterile vegetations attach to heart valves. NBTE is typically found in patients with
malignancies or autoimmune disorders. Although surgical interventions are sometimes performed, the appropriate indication and timing are still unclear. Here, we describe a 72-year-old woman diagnosed with
adenosquamous carcinoma of the lung. She was initially diagnosed as pT2aN0M0 and underwent RUL lobectomy. After nine months,
lung cancer recurred, and she underwent treatment with cytotoxic
chemotherapy. However, images showed progression after only one month. Rebiopsy revealed she had comutation of de novo EGFR L858R and T790M. Treatment was changed to
gefitinib. After one month, she experienced
loss of consciousness. Brain magnetic resonance imaging (MRI) showed multiple lesions resembling
infarctions or
metastases. Chest computed tomography (CT) revealed progression.
Osimertinib was prescribed and she underwent echocardiography to rule out the possibility of a cardiogenic
embolism. Surprisingly, severe
mitral regurgitation and a massive vegetation on the mitral valve were found. Cardiologists recommended surgery due to the severity of the embolic event and valve dysfunction, but it was decided to continue
antibiotics,
osimertinib, and
anticoagulants instead of surgery due to the patient's poor general condition and the possibility of NBTE. Six weeks later, the patient's condition markedly improved and echocardiography revealed a marked reduction in vegetation size. Clinicians should be aware that targeted
therapy can be effective in treating severe
cancer complications, such as NBTE, as evidenced by the successful treatment of
lung cancer with
osimertinib. This option should be considered, particularly for elderly
lung cancer patients, before resorting to surgery as a first-line treatment for NBTE.