A 53-year-old man with Val30Met hereditary transthyretin amyloidosis developed an isolated pulmonary valve mass with severe pulmonary regurgitation that was confirmed by histopathology to be Congo red-positive amyloid deposition, mimicking infective endocarditis in the setting of concurrent MSSA bacteremia.
Key Findings
Results
Amyloid deposition can occur as an isolated pulmonary valve mass in Val30Met hATTR without overt myocardial involvement.
The patient was a 53-year-old man with known Val30Met hereditary transthyretin amyloidosis (hATTR).
Histopathological examination of the surgically excised pulmonary valve mass demonstrated Congo red-positive amyloid deposition.
No overt myocardial involvement was described, making this an atypical cardiac manifestation of hATTR.
The case highlights that hATTR cardiac involvement can extend beyond myocardial infiltration to include valvular structures.
Results
The pulmonary valve amyloid mass presented with a highly mobile morphology and caused severe pulmonary regurgitation.
Echocardiography identified a highly mobile pulmonary valve mass.
The mass was associated with severe pulmonary regurgitation.
Cardiac magnetic resonance imaging was also used to characterize the lesion.
Neither echocardiography nor cardiac MRI could establish the etiology of the mass prior to surgery.
Results
Concurrent MSSA bacteremia caused diagnostic confusion by raising suspicion for infective endocarditis.
The patient had concomitant methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia at the time of presentation.
The combination of a mobile valve mass and bacteremia clinically mimicked infective endocarditis.
Surgical excision was ultimately required to establish the correct diagnosis histopathologically.
This case illustrates the diagnostic challenge when amyloid valve deposition co-occurs with an unrelated infectious process.
Results
Surgical excision and pulmonary valve replacement were performed as the definitive treatment and diagnostic approach.
The patient underwent surgical excision of the pulmonary valve mass.
Pulmonary valve replacement was performed concomitantly.
Histopathological examination of the excised tissue confirmed the diagnosis of amyloid deposition.
Congo red positivity on histopathology was the confirmatory finding.
Discussion
Isolated pulmonary valvular amyloid infiltration represents an atypical and previously underrecognized cardiac manifestation of hATTR amyloidosis.
The authors state this case 'highlights that atypical cardiac manifestations beyond myocardial infiltration can occur in patients with hATTR.'
Val30Met is the specific pathogenic variant associated with this presentation.
The pulmonary valve is an unusual site for amyloid deposition in the context of hATTR.
The case underscores the importance of considering amyloid in the differential diagnosis of valve masses in patients with known hATTR, even in the setting of bacteremia.
What This Means
This research presents a single patient case report describing an unusual complication of a hereditary disease called transthyretin amyloidosis (hATTR), which causes abnormal protein deposits in body tissues. A 53-year-old man with a specific genetic form of this disease (Val30Met) developed a mobile mass on his pulmonary heart valve—the valve controlling blood flow from the heart to the lungs—which caused severe leakage of that valve. At the same time, he had a blood infection with a common bacterium (Staphylococcus aureus), which made doctors suspect the mass was a vegetation caused by heart valve infection (infective endocarditis), a serious and life-threatening condition.
Because imaging tests (echocardiography and cardiac MRI) could not definitively determine what the mass was, surgeons removed it and replaced the valve. Laboratory analysis of the removed tissue confirmed the mass was made of amyloid protein deposits—not infected tissue—by showing a characteristic positive result with a special stain called Congo red. Importantly, the patient's heart muscle itself did not show the typical amyloid infiltration usually seen in this disease, making this an unusual presentation.
This research suggests that in patients with hereditary transthyretin amyloidosis, amyloid protein can deposit in heart valves—not just in the heart muscle—and can closely mimic a dangerous infection. This matters because the two conditions require very different treatments: infected valves are treated with antibiotics and sometimes surgery for infection control, while amyloid deposits are managed differently. Clinicians caring for patients with known hATTR should be aware that an unusual valve mass may represent amyloid deposition even when a concurrent infection is present, and tissue sampling may be necessary to make the correct diagnosis.