What is the clinical evidence from this study?

Study design: Case Report. Population: Nonbacterial thrombotic endocarditis and metastatic breast cancer (n=1).

What question did this study set out to answer?

To highlight the challenges in diagnosing nonbacterial thrombotic endocarditis (NBTE) in patients with advanced malignancies such as metastatic breast cancer.

May 9, 2026Open Access

Echocardiographically occult nonbacterial thrombotic endocarditis with tumor cell-containing valvular vegetations in metastatic breast cancer

Key Result

Malignancy-associated nonbacterial thrombotic endocarditis with tumor cell-containing vegetations can remain echocardiographically occult despite extensive arterial embolization.

Key Points

To highlight the challenges in diagnosing nonbacterial thrombotic endocarditis (NBTE) in patients with advanced malignancies such as metastatic breast cancer.
Case presentation of a 37-year-old woman with ischemic strokes and multiple organ failure.
Utilized transesophageal echocardiography (TEE) and various blood tests to diagnose and manage the condition.
Postmortem examination and histopathological analysis of valvular vegetations.
Patient presented with ischemic strokes and progressive complications despite treatment, including thrombocytopenia and DIC.
Postmortem findings revealed tumor cell-containing vegetations on heart valves and fibrin-rich microthrombi in renal arterioles.
Diagnosis of NBTE was confirmed at autopsy despite initial echocardiographic limitations.

Study Design

Type

Case Report (n=1)

Multicenter

Structured PICO

Population

A 37-year-old woman presenting with multifocal ischemic strokes and visceral infarctions, later found to have bilateral metastatic invasive lobular breast carcinoma.

This case highlights that malignancy-associated nonbacterial thrombotic endocarditis can be echocardiographically occult and that vegetations may contain tumor cells.

Limitations

Advanced techniques such as 3D TEE or shorter-interval repeat imaging were not feasible.
Trephine biopsy and breast tissue sampling were deferred due to critical thrombocytopenia, active bleeding, and DIC.
Immune-complex staining was not performed.

Abstract

BACKGROUND: Nonbacterial thrombotic endocarditis (NBTE) is an uncommon but important cause of systemic arterial embolism, most often occurring in advanced malignancy. Diagnosis is frequently difficult because vegetations may be small, transient, or not visualized on echocardiography, which may delay recognition. CASE PRESENTATION: A 37-year-old woman presented with multifocal ischemic strokes and visceral infarctions. Initial transesophageal echocardiography (TEE) showed a small isoechoic structure on the mitral valve, interpreted as a possible vegetation. Despite empiric broad-spectrum antibiotics and therapeutic anticoagulation, she developed progressive thrombocytopenia, hemolytic anemia, disseminated intravascular coagulation, and multiorgan failure. Repeated blood cultures were negative, and repeat TEE showed no valvular masses. The patient died despite plasma exchange, plasma infusion, corticosteroids, and transfusion support. Postmortem examination revealed previously undiagnosed bilateral metastatic invasive lobular breast carcinoma. Histopathology demonstrated tumor cell-containing fibrin-platelet vegetations on the mitral and tricuspid valves, with fibrin-rich microthrombi in renal arterioles consistent with secondary paraneoplastic thrombotic microangiopathy. CONCLUSION: This autopsy-confirmed case underscores that malignancy-associated NBTE may remain echocardiographically occult despite extensive arterial embolization. It also demonstrates that valvular thrombi may incorporate tumor cells, providing a direct substrate for embolic events.

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