When is a mass not a mass? An unusual presentation of prominent crista terminalis

Prominent crista terminalis mimicking a right atrial mass: A case report and brief review of the literature

The crista terminalis is a normal anatomical structure, characterized by a smooth muscular ridge along the superior aspect of the right atrium. It is derived from resorption of the right valve of the sinus venosus and it divides the right atrium into smooth posteromedial and trabeculated anterolateral portions. Crista terminalis is not normally detected in the standard views of transthoracic echocardiogram and non-gated CT of the chest. In rare circumstances, the crista terminalis may be prominent and could lead to misdiagnosis as a malignant process, such as in our case. A comprehensive understanding of the crista terminalis anatomy, and its characteristic appearance on transthoracic echocardiogram, CT and PET/CT will minimize the risk of misdiagnosis and will avoid patient anxiety with more extensive examinations. Here, we present a case of a 78-year-old male with newly diagnosed high-grade invasive urinary bladder urothelial carcinoma. Pre-operative transthoracic echocardiogram reported as 2 cm right atrial mass concerning a metastasis lesion. Subsequent evaluation with MRI cardiac morphology confirmed the diagnosis of benign prominent crista terminalis, a normal anatomical structure.

An unusual presentation of prominent crista terminalis mimicking a right atrial mass: a case report

Background

The crista terminalis is a variation of normal anatomical structure within the right atrium which may be misdiagnosed with an abnormal atrial mass normally visualized in the standard views on the transthoracic echocardiogram.

Case presentation

In this case presentation, we demonstrated a rare case report describing the accidental discovery of a right atrial mass-like structure in a 54-year old Asian man without physical discomfort during an echocardiographic examination. These findings naturally caused some concern as the differential diagnosis such as right atrial myxoma or thrombus and further examination were organized. The subsequent positron emission tomography/magnetic resonance imaging (PET/MRI) differentiated a true right atrial mass from a strip extending into the atrium in accordance with prominent crista terminalis.

Conclusion

A preferable understanding of the complex anatomy and PET/MRI appearance of a prominent crista terminalis will minimize the misdiagnosis of this structure and avoiding unnecessary anxiety and more invasive examinations.

Electronic supplementary material

The online version of this article (10.1186/s12872-018-0925-y) contains supplementary material, which is available to authorized users.

Prominent Crista Terminalis in a Fetus

BACKGROUND

The crista terminalis is a normal cardiac structure located in the right atrium. It is not usually seen using standard view transthoracic echocardiography techniques, but on occasion, hypertrophy allows for easy visualization of this structure, which can be mistakenly labelled pathologic.

CASE

We report the first known case of a prominent crista terminalis detected in a fetus.

CONCLUSIONS

This case confirms the presence of a prominent crista terminalis in a developing fetus, a variant which was exclusively described in the pediatric and adult populations until now. Although a prominent crista terminalis is a benign variant, the correct identification of this structure has important diagnostic implications. This report aims to increase familiarity with the appearance of a prominent crista terminalis on both fetal echocardiography and newborn transthoracic echocardiography in hopes that this will aid in the correct diagnosis of this variant in the future.

Normal Variants in Echocardiography

Echocardiography is a powerful and convenient tool used routinely in the cardiac evaluation of many patients. Improved resolution and visualization of cardiac anatomy has led to the discovery of many normal variant structures that have no known pathologic consequence. Importantly, these findings may masquerade as pathology prompting unnecessary further evaluation at the expense of anxiety, cost, or potential harm. This review provides an updated and comprehensive collection of normal anatomic variants on both transthoracic and transesophageal imaging.