Case Report Sternalis Muscle: An Unexpected Finding during Mastectomy Prakash K. Sasmal, 1 Susanta Meher, 1 Tushar S. Mishra, 1 N. Deep, 2 Prabhas R. Tripathy, 3 and Satyajit Rath 1 1 Department of Surgical Discipline, All India Institute of Medical Sciences, Bhubaneswar 751019, India 2 Department of Radiodiagnosis, All India Institute of Medical Sciences, Bhubaneswar 751019, India 3 Department of Anatomy, All India Institute of Medical Sciences, Bhubaneswar 751019, India Correspondence should be addressed to Prakash K. Sasmal; drpksasmal@gmail.com Received 30 June 2015; Revised 27 August 2015; Accepted 13 September 2015 Academic Editor: Boris Kirshtein Copyright © 2015 Prakash K. Sasmal et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Sternalis muscle also called rectus sternalis, rectus thoracis, or episternalis is an anomalous muscle of the anterior chest wall with unknown anatomical function. It is regularly observed in lower animal but infrequently in humans. Presence of this muscle can create confusion with tumours of the anterior chest wall during routine mammography. Although less is known about its origin and innervations, knowledge about this muscle can have many clinical implications. A case of unilateral sternalis muscle detected during mastectomy, in a female with carcinoma of the right breast, is being reported with a brief review of the literature and highlighting its clinical signifcance. 1. Introduction Sternalis muscle is an uncommon anatomical variant of anterior chest wall muscles [1]. It is a vertical strip of thin ribbonlike muscle located in the parasternal region, super- fcial to pectoralis major, with its fbre oriented parallel to the sternum and perpendicular to the fbres of the pectoralis major muscle. Cabrollius, in 1604, was the frst to report the presence of this entity, although Du Puy, in 1726, gave a more precise description of it [2, 3]. Various nomenclatures of this muscle are found in the literature including musculus sternalis presternalis, sternalis muscle, sternalis brottrum, or thoracis [4, 5]. Tis report of an incidentally detected sternalis muscle is being presented for its clinical signifcance in day- to-day clinical practice. 2. Case Report A 39-year-old female patient presented to the Surgical Out- patient Department of AIIMS, Bhubaneswar, with a right breast lump of approximately 3 cm in diameter. On evaluation she was found to have a T 2 N 1 M 0 carcinoma in her right breast. Afer a detailed workup she was posted for modifed radical mastectomy of the right breast. During mastectomy a thin ribbonlike muscle was found in the parasternal area with its fbres oriented craniocaudally, parallel to the sternum and perpendicular to the fbres of the right pectoralis major muscle (Figure 1(a)). Te muscle was thin, approximately 10 cm in length and 3 cm in breadth. Fibrofatty breast tissue was found below the muscle which was cleared during dissection. It was arising from the sternum below the sternal head of the sternocleidomastoid muscle of the right side and inserted into the costal cartilages of the 5th and 6th right rib and its tendon was separate from the rectus abdominis muscle. Magnetic resonance imaging (MRI) of the anterior chest wall was done postoperatively afer taking due consent from the patient, to look for any similar muscle on the opposite site (Figure 1(b)) although it was found to be absent. 3. Discussion In 2001, Jelev et al. defned the characteristics of the muscle as (1) location between the anterior thoracic fascia and pectoral fascia, (2) origin from the sternum or infraclavicular area, and (3) its insertion into the rectus sheath, lower ribs, costal cartilages, or external oblique aponeurosis [1, 6]. In our case Hindawi Publishing Corporation Case Reports in Surgery Volume 2015, Article ID 723198, 3 pages http://dx.doi.org/10.1155/2015/723198