First described in 1856 by their namesake, Dr. Vilem Dusan Lambl, Lambl excrescences (LEs) are filiform extensions arising on the closing surface of cardiac valves [3,6,9]. Their pathophysiology is uncertain, but many have considered them “wear-and-tear” lesions resulting from hemodynamic shear stress [9,12]. Importantly, they have been implicated as potential causes for otherwise idiopathic cerebrovascular events [3,7,8,10,12,14,15]. However, the literature discussing LEs is scant, with only a few case reports and reviews [1,3,7,8,10,11,14,15].

While similar in both gross and histopathologic appearance to papillary fibroelastomas (PFEs), a benign neoplasm of the endocardium, LEs are architecturally simpler (without generative branching), typically smaller, and believed to be less prone to complication [2,3,5]. More recently, differences in biology have been reported with the observation that a subset of PFEs harbor KRAS mutation – a phenomenon not observed in LEs [4].

LEs have been regarded as “rare” clinical entities [3]. However, their prevalence within the normal population has only been addressed in two prior series [9,12]. These studies examined a relatively small number of hearts (56 and 126 hearts, respectively), and reported an LE prevalence ranging from 84% to 90%. These studies were limited in that the ages of the examined cohorts were not provided in one series and in the other was primarily an older population (mean age, 71 years). Given that the prevalence of LEs is thought to increase with age [9], these proportions may be skewed due to the age range of the subjects examined. Thus, a nonbiased estimation of the characteristics of LEs within the normal human population is warranted, particularly given the unknowns regarding their clinical import.