Pathologic examination of Lambl's excrescence.

We read with interest the article titled “Endovascular transcatheter aortic valve implantation: An evolving standard” published by Sfeir PM et al. In view of the greying of the population and the higher age of patients, severe aortic stenosis patients who undergo transcatheter aortic valve implantation are more likely to have Lambl’s excrescences than 10 years ago. Lambl’s excrescences are small, mobile valvular strands made up of connective tissue. They are thin (o1 mm), long (410 mm) filiform projections from heart valves that show undulating independent motion. They are more commonly seen on the mitral valve than on the aortic valve, typically near the closure line of the mitral valve. Although it was first reported that they were composed of fibrin, morphologic analysis revealed the presence of collagen. Several previous case reports have shown no common morphologic and histologic structures for Lambl’s excrescences. Here, we wish to share our experience of a patient with Lambl’s excrescence. We have included histologic images of the excrescence. While providing anesthesia for a patient undergoing mitral valve replacement surgery, we performed transesophageal echocardiography and found the Lambl’s excrescence on the aortic valve in the form of a 12-mm fibrous tissue (Fig 1). We presumed it was a flapping piece torn from the commissure between the right and left coronary cusps along the edge of the left coronary cusp. Pathologic examination of the tissue with hematoxylin eosin staining revealed that the structure consisted of connective tissue covered by a single layer of endothelial cells (Fig 2). Examination with Elastica Van Gieson’s stain showed that it had a collagenous structure with elastic fibers inside and was surrounded by loose connective tissue (Fig 3). Hence, it was diagnosed as a typical Lambl’s excrescence. Since these excrescences are similar in composition to cardiac valves, the strand was assumed to have come off the surface of the valve to which the strand was attached due to the flow of blood.