Ectopic pleomorphic adenoma in intramuscular plane of sternocleidomastoid muscle: A rare case report

Yeshwant Lamture; Aditya Ghunage

doi:10.4103/jdmimsu.jdmimsu_89_19

CASE REPORT

Year : 2019 | Volume : 14 | Issue : 4 | Page : 417-419

Ectopic pleomorphic adenoma in intramuscular plane of sternocleidomastoid muscle: A rare case report

Yeshwant Lamture, Aditya Ghunage
Department of General Surgery, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences, Wardha, Maharashtra, India

Date of Submission	24-May-2019
Date of Decision	30-Aug-2019
Date of Acceptance	15-Nov-2019
Date of Web Publication	16-Jul-2020

Correspondence Address:
Dr. Yeshwant Lamture
AVBRH Campus, Sawangi (Meghe), Wardha, Maharashtra
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jdmimsu.jdmimsu_89_19

Abstract

Pleomorphic adenoma is the most common salivary parotid gland tumor. It is a benign tumor, represents 45% of parotid gland tumors, and 6.5% are found in the minor salivary glands. Only five cases of ectopic mixed salivary gland tumors in the upper neck in adult patients have been reported. The present case had an ectopic pleomorphic adenoma in intramuscular plane of sternocleidomastoid muscle. Ultrasound and fine-needle aspiration biopsy revealed swelling to be pleomorphic adenoma. Intraoperatively, the swelling was not arising from the parotid gland. Although pleomorphic adenoma arising from heterotropic salivary gland tissue is rare. Pleomorphic adenoma is the most common type of salivary gland tumor. Salivary gland tumor rarely occurs in ectopic sites. Good clinical acumen along with proper diagnostic techniques is required in the diagnosis of such cases.

Keywords: Ectopic pleomorphic adenoma, heterotopic salivary tissue, neck swellings, salivary gland tumor

How to cite this article:
Lamture Y, Ghunage A. Ectopic pleomorphic adenoma in intramuscular plane of sternocleidomastoid muscle: A rare case report. J Datta Meghe Inst Med Sci Univ 2019;14:417-9

How to cite this URL:
Lamture Y, Ghunage A. Ectopic pleomorphic adenoma in intramuscular plane of sternocleidomastoid muscle: A rare case report. J Datta Meghe Inst Med Sci Univ [serial online] 2019 [cited 2021 Jan 15];14:417-9. Available from: http://www.journaldmims.com/text.asp?2019/14/4/417/289864

Introduction

Pleomorphic adenoma is the most common tumor of mixed salivary gland. It is the most common tumor of the parotid gland. The tumor is solitary and presents as slow-growing, painless, firm single nodular mass. It is a benign tumor arises from the parotid gland in 84% of cases and the rest from other salivary glands and represents 45% of parotid gland tumors. Only 6.5% are found in the minor salivary glands.^[1]

Heterotopic salivary gland tissue (HSGT) is a normal arrangement of salivary tissue found in locations external to major and minor salivary glands. The occurrence of HSGT in the neck is rare, mostly found in deeper planes of the tissue, and it may manifest as a mass, cyst, or a draining sinus.^[2] Only five cases of ectopic mixed salivary gland tumors in the upper neck in adult patients have been reported.^[1]

Case Report

A 26-year-old female came to the surgery OPD with complaints of swelling below the left angle of mandible for 7 years which was spontaneous in onset gradually progressive. The swelling was initially small which later progressed to current size of 6 cm × 5 cm. On clinical examination, the lump was palpable posteroinferior to the left angle of the mandible and anterior to the anterior border of sternocleidomastoid muscle. The lump was spherical in shape with smooth surface, skin over the swelling was normal, no visible pulsations, and no scar marks. The swelling was firm in consistency, nontender with normal temperature on the swelling, the lump was mobile in one direction perpendicular to fibers of sternocleidomastoid muscle, and mobility was restricted on contracting muscle. It was noncompressible, nonpulsatile, and there was no swelling palpable in oral cavity. No other significant lump was palpable in the neck. Indirect laryngoscopy and video direct laryngoscopy was done to exclude any extension inside the neck. Clinically, a provisional diagnosis of cervical mass arising from sternocleidomastoid muscle was made. Ultrasonographic (USG) examination of the neck showed a well-defined large encapsulated lesion of size 56 mm × 32 mm seen in the upper part of neck region in the intramuscular part of sternocleidomastoid muscle with tiny calcifications inside of it. USG was suggestive of a lymph node mass. Bilateral submandibular gland, parotid gland, and thyroid gland were normal. For further confirmation, an ultrasound-guided fine-needle aspiration cytology (FNAC) was done which showed benign epithelial cells in chondromyxoid background suggestive of pleomorphic adenoma [Figure 1].

Figure 1: Fine-needle aspiration cytology showing chondromyxoid stroma and epithelial cells

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The lesion was excised with safety margins under general anesthesia. It was found to be in the plane of sternomastoid muscle and had no relation to parotid and submandibular gland, the lesion was excised completely with adequate margins. Grossly, the specimen was well circumscribed, measuring 5 cm × 5 cm × 3 cm, and had a shiny, white cut surface. The specimen was sent for histopathological examination, which showed epithelial and connective tissue components [Figure 2] and [Figure 3].

Figure 2: Histopathology – Myxo-chondroid component with epithelial cells arranged nests, cords, and strands

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Figure 3: Histopathology – Myxo-chondroid component with epithelial cells arranged nests, cords, and strands

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The connective tissue was myxo-chondroid. Epithelial cells were arranged in the form of nests, cords, and strands. Multiple ductal areas enclosing mucoid material were seen. The features were suggestive of pleomorphic adenoma.

Discussion

Pleomorphic adenoma originates from the epithelial and myoepithelial cells of the intercalary ducts and is characterized histologically by different types of tissues (glandular, epithelial, myoepithelial, myxoid, fibrous, chondral, and bony).

HSGT is a normal arrangement of salivary tissue found in locations external to major and minor salivary glands. The occurrence of HSGT in the neck is rare, mostly found in deeper planes of the tissue. The embryological development for this rare condition is not known. One of the theories of HSGT in the neck is defective closure of the precervical His sinus, with internal heteroplasia.^[3] The situation of HSGTs in the lower neck is suggestive of its relationship to the branchial apparatus, specially the precervical sinus. In the 6^th week of intrauterine life, the 1^st and 2^nd branchial arches grows and reaches toward 3^rd and 4^th arch to form ectodermal sinus. This sinus is normally obliterated by the end of 2^nd month, failure of which leads to cystic vestiges in the neck. These ectoderm derived cysts are potential sites to be capable of giving rise to salivary tissue.^[2]

Since HSGT is a true salivary tissue, it can be affected by same disorders as of major and minor salivary glands such as infective, inflammatory, and neoplastic. Only five previous adult cases of pleomorphic adenoma in the upper neck have been reported till date. The first case of ectopic pleomorphic adenoma of neck was described by Pesavento and Ferlito in 1976. Two years later, Hulbert published the second case followed by the third one reported by Ordonez et al. and Domenico et al. reported the fourth case in 2008 and in 2012 Luksić et al. presented the fifth one.^[1] The presence of ectopic salivary tumor in an unusual location can produce a diagnostic dilemma to the surgeons for which histopathological diagnosis is needed. Such lesions need to be assessed and investigated thoroughly to rule out malignancy. Hence, as to know if it is primary or a metastatic swelling. In such cases, USG and FNAC can be very conclusive. This minimal invasive method allows to differentiate between benign and malignant tumors of the salivary glands and providing other advantages such as low cost and easy to perform. In addition, it is relatively painless, well tolerated, and with a very low risk of cancer cell implantation in needle pathway. Treatment modality for pleomorphic adenoma is resection with tumor free margins. In spite of being a benign neoplasm, inadequate management of pleomorphic adenoma may lead to problems such as local recurrence and malignant transformation into Carcinoma Ex-Pleomorphic Adenoma or carcinosarcoma, and even more rarely metastasizing pleomorphic adenoma may occur.^{[4],[5],[6],[7],[8],[9],[10],[11]}

Conclusion

Patient can present with various neck swellings. Rarely, a tumor of such ectopic salivary tissue can be seen, for which a through radio pathological correlation is needed. Detection of malignant tumors requires appropriate investigation and treatment.

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

Nil.

Conflicts of interest

There are no conflicts of interest.

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