Introduction: Infective endocarditis (IE) is a rare disease which manifests in different ways.
Case outline: We are presenting a female patient who was suspected of IE based on the presence of fever, accelerated erythrocyte sedimentation rate, increased levels of C-reactive protein and echocardiographic findings of filamentous structures on the aortic valve which were assumed to be vegetation. Because of the well-known fact that in the pre-antibiotic era IE was almost always a fatal disease, empirical antibiotic therapy was conducted despite the absence of clear criteria for IE and it resulted in a satisfactory outcome. The course of the disease and the persistence of echocardiographic findings with a completely competent aortic valve, suggested us to consider the diagnosis of Lambl's excrescences. There was no indication for surgical treatment in our patient; so that in the absence of pathological confirmation our diagnostic dilemma was left unresolved.
Conclusion: In patients with typical clinical features of IE and filamentous structures on the cardiac valves that are completely competent, Lambl's excrescences should be kept in mind as a possible differential diagnosis.