Prevalence of the sternalis muscle in Chilean population: A computed tomography study

Abstract

The sternalis muscle is an anatomic variation that was first described in 1604. It has been studied in different populations worldwide, showing a widespread prevalence. The clinical importance of this muscle depends on mammographic evaluation that can lead to an erroneous diagnosis of breast cancer. Our objective is to determine the prevalence of sternalis muscle in Chilean population, characterizing it by gender and side of presentation using computerized tomography. To our current knowledge, there are no studies determining its prevalence using this method. No institutional review board approval was required for this analysis, which involved data made anonymous from men and women who underwent computerized tomography imaging for diagnostic purpose between January 2012 and February 2014. A retrospective radiological identification of the sternalis muscle was performed in 2288 axial computerized tomographies to determine the overall gender and side distribution. Data were analyzed using chi-square test. The sternalis muscle was present in 20 out of 2288 computerized tomographies, and its prevalence in the Chilean population was 0.87%. This muscle was found in male (12/1064, 1.12%) and female subjects (8/1224, 0.65%), no statistical difference between genders was found. Among people with the sternalis muscle, 12 (0.52%) presented it on the left side, 6 (0.26%) on the right side, and only 2 (0.09%) had bilateral sternalis muscle. The Chilean population has the lowest prevalence of sternalis muscle ever reported.