|Year : 2021 | Volume
| Issue : 1 | Page : 52-54
Incidentally detected anomalous pectoralis major muscle during reconstruction of oral cavity cancer
Amitabh Jena1, Gajjala Sivanath Reddy2, Rashmi Patnayak3, Sarla Settipalli4
1 Department of Surgical Oncology, IMS and SUM Hospital, Bhubaneswar, Odisha, India
2 Department of Surgical Oncology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
3 Department of Pathology, IMS and SUM Hospital, Bhubaneswar, Odisha, India
4 Department of Radiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
|Date of Submission||13-Dec-2019|
|Date of Acceptance||15-Feb-2021|
|Date of Web Publication||07-Apr-2021|
Dr. Rashmi Patnayak
Department of Pathology, IMS and SUM Hospital, Bhubaneswar, Odisha
Source of Support: None, Conflict of Interest: None
The congenital deficiency of pectoralis major muscle is quite uncommon. Only a few cases are described in the literature that too in cadavers. Recently, we came across a case of deficient pectoralis major while harvesting pectoralis major myocutaneous (PMMC) flap for reconstruction following right composite resection for carcinoma of the right buccal mucosa in a 50-year-old female. The external appearance of the anterior chest wall was normal. During surgery, we found that the clavicular head and sternal portion of the sternocostal head of the right pectoralis major muscle were absent and the costal portion of the sternocostal head was deficient over the medial aspect. A normal pectoralis minor was present. This deficiency may be congenital in nature. We present this case to highlight this uncommon condition, and this may be the only case report till now wherein deficient pectoralis major was used for PMMC flap reconstruction of oral cavity defect.
Keywords: Deficiency, pectoralis major muscle, pectoralis major myocutaneous flap reconstruction
|How to cite this article:|
Jena A, Reddy GS, Patnayak R, Settipalli S. Incidentally detected anomalous pectoralis major muscle during reconstruction of oral cavity cancer. J Anat Soc India 2021;70:52-4
|How to cite this URL:|
Jena A, Reddy GS, Patnayak R, Settipalli S. Incidentally detected anomalous pectoralis major muscle during reconstruction of oral cavity cancer. J Anat Soc India [serial online] 2021 [cited 2021 Apr 22];70:52-4. Available from: https://www.jasi.org.in/text.asp?2021/70/1/52/313160
| Introduction|| |
The pectoralis major is a large thick triangular fan-shaped extrinsic muscle of the anterior thoracic wall. It has clavicular and sternocostal heads. The clavicular head takes origin from the medial third or half of the clavicle. The sternocostal head originates from the sternum, the costal cartilages of the upper six ribs, and the anterior lamina of the rectus sheath. From these two origins, the fibers converge toward their insertion into the lateral lip of the bicipital groove of the humerus [Figure 1]a. The medial pectoral nerve innervates solely the lower pectoralis major segments, and the lateral pectoral nerve is involved in the innervation of the clavicular portion and the upper segments of the sternocostal portion.
|Figure 1: (a) Normal anatomy of pectoralis major. (b) Absence of the clavicular head, sternal and medial part of the costal portion of the sternocostal head of the right pectoralis major muscle, and presence of normal pectoralis minor|
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There are various anomalies of the pectoralis muscle described in the literature, including few from India., However, most of the reported cases were anatomical findings from cadavers.
Anomalies in the pectoralis muscle are more likely to occur in the clavicular portion, being the most proximal and the earliest portion to attach, whereas the sternocostal portion is either reduced or absent.
In our report, we describe a case of deficient pectoralis major muscle in a female patient, incidentally detected while doing reconstruction by pectoralis major myocutaneous (PMMC) flap for carcinoma buccal mucosa. Hereby, we discuss the rarity of the condition and how it affected our surgical management.
| Case Report|| |
This is a case of a 50-year-old female diagnosed with carcinoma of the right buccal mucosa. We planned for right composite resection and reconstruction of the defect with PMMC flap. The external appearance of the anterior thoracic wall was apparently normal with well-developed breasts.
While harvesting PMMC flap, we observed that the pectoralis major muscle is only originating from the lateral part of the costal portion of the sternocostal head and was well developed. The clavicular head and the sternal portion of the sternocostal head of the right pectoralis major muscle were completely absent. The medial part of the costal portion of the sternocostal head was also absent. Insertion of the muscle was into the lateral lip of the bicipital groove of the humerus. A normal pectoralis minor was present [Figure 1]b. The vascular supply to the muscle was found to be intact at its normal anatomical position supplying the pectoralis major by pectoral branch of acromiothoracic vessels [Figure 2]. The deltoid and subclavius muscles were not hypertrophied.
We did not explore the left side, to avoid unnecessary morbidity; also, it was not required for the operative procedure. Hence, the status of the left pectoralis muscles at the time of surgery could not be commented upon. Externally, there was no abnormality noted in the patient's chest wall. As a routine preoperative work-up, chest X-ray was done. Preoperative computed tomography scan or magnetic resonance imaging (MRI) of the chest was not done, as for routine reconstruction with PMMC flap, these investigations were not required.
The skin paddle was marked and was harvested along with the whole muscle. It included the full length of the muscle up to its insertion with intact vascular pedicle [Figure 2]. Then, the flap was used for reconstruction of oral cavity defect.
Postoperative period was uneventful without any complications such as flap necrosis and wound infection. The patient was discharged on the 10th postoperative day with advice to take oral diet.
After a follow-up period of 8 months, we noticed that both the flap donor and reconstructed sites were healthy with acceptable cosmetic result. MRI of the chest showed absent pectoralis major muscle in the right side which was used in toto for reconstruction. Pectoralis minors of both sides and pectoralis major of the left side were intact [Figure 3].
|Figure 3: Magnetic resonance imaging (axial and coronal image) of the chest showing absent pectoralis major muscle (A – pectoralis major) in the right side which was used in toto for reconstruction and pectoralis minor (B – pectoralis minor), intact pectoralis major of the left side, and pectoralis minors|
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In a previous study, we have reported the outcome of PMMC flap reconstruction in 140 female patients. However, none of those cases showed this type of deficient pectoralis major muscle.
| Discussion|| |
In the literature, there are reports of various anomalies of the pectoralis muscle. Even drawings by Leonardo da Vinci in the 16th century demonstrated this type of defect. Poland's syndrome is the most common condition in which pectoral muscle anomalies are noted., The combination of a lack of the pectoralis major and/or minor muscles with skeletal, vascular, and surface feature anomalies in the ipsilateral upper limb is referred to as Poland's syndrome. Poland's syndrome is characterized by the absence of the pectoralis major and minor muscles, hypoplasia or complete absence of the breast, costal cartilage and rib defects, and hypoplasia of subcutaneous chest wall tissue. The congenital absence of the pectoralis muscle is usually a common feature of Poland syndrome. Hypoplasia of the sternocostal portion of the pectoralis is the most significant feature. It is most frequently associated with homolateral breast hypoplasia. A nonsyndromic congenital absence of the pectoralis muscle is rare. These types of absences are usually partial and unilateral.,
The pectoralis major and minor muscles develop from a muscle mass that appears during the 5th month in utero., The mass of muscle attaches to the clavicle, fans out, and subsequently attaches to the sternum and ribs. Hence, anomalies are more likely in the clavicular portion, whereas the sternocostal portion is either reduced or absent.
The cause of this disease is unknown, most likely the cause being a vascular abnormality that causes failure of development. It is believed that subclavian artery supply disruption sequence may be the underlying cause. It is characterized by an intrauterine damage to the blood supply coming from the subclavian artery. Pectoral muscle anomalies, though not common, were among the most frequently encountered. As far as functional aspect is concerned, several authors agree that the patients with congenital deficits in pectoral muscles have little or no functional deficits in normal daily activities. However, during reconstruction of PMMC flap, an anomalous pectoralis muscle may pose a problem.
In our case, since there was intact vascular supply, this anomalous pectoralis major did not create any problem. The patient is doing well after the reconstruction. In cases where there is a complete absence of pectoralis major muscle option of reconstruction with free flaps should be considered.
We conclude this case of deficient pectoralis muscle incidentally encountered at the time of surgery, by highlighting its relative rarity.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient (s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]