Abstract
Parapharyngeal space (PPS) tumors constitute about 0.5% of all the head and neck tumors.Tumors arising de novo from ectopic salivary tissue in the PPS are very rare. We present a huge primary parapharyngeal pleomorphic adenoma arising from ectopic salivary tissue. Case is being presented for its unusually large size at presentation and its rarity.
Keywords: Pleomorphic adenoma, Parapharyngeal space tumors, Surgery
Introduction
Parapharyngeal space (PPS) tumors account for about 0.5% of all head and neck tumors [1]. Pleomorphic adenomas (PA) arising de novo from the PPS are infrequent; most ENT and head and neck surgeons will only see a handful of cases in their practice. Here, we describe a unique case of giant PPS tumor arising de novo from the salivary gland tissue managed at our institute.
Case Report
An elderly female patient came with a right sided gradually progressive painless neck swelling for 15 years. It was well-defined, about 30 cm × 24 cm size, with a bossellated surface having trophic ulcers and variable consistency extending superiorly up to mastoid process and overhanging the clavicle below. Medially it extended up to the contralateral sternocleidomastoid and laterally up to the ipsilateral trapezius muscle (Fig. 1). The ipsilateral tonsil and the lateral pharyngeal wall were pushed medially.
Fig. 1.
The right sided swelling with a bossellated surface extending superiorly up to the level of mastoid process and inferiorly overhanging the clavicle, medially the tumor extended up to the anterior border of contra lateral sternocleidomastoid muscle
A Computerized tomography (CT) scan of the neck revealed a multinodular heterogeneously enhancing mass abutting both the lobes of right parotid gland with loss of intervening fat plane with areas of necrosis and calcification. The lesion was compressing the ipsilateral neck structures and vessels with extension into the right PPS, floor of mouth and the right paraglottic space pushing the larynx towards left. Parapharyngeal fat was not visualized but perilesional fat planes were maintained (Fig. 2). This made us believe that the tumor was arising from the deep lobe of the parotid gland. The fine needle aspiration cytology (FNAC) of the mass was suggestive of PA.
Fig. 2.
A multinodular heterogeneously enhancing swelling extending up to floor of mouth above abutting the superficial and deep lobes of the right parotid gland with loss of intervening fat plane. Areas of necrosis and calcification are visible. The parapharyngeal fat was not visualized
The patient was prepared for total conservative parotidectomy. A double incision was made for the horizontal limb of modified Blair’s incision in the neck over the tumor extending right up to the symphysis menti. It enclosed the area of ulceration while taking adequate care to preserve enough skin in the upper and lower flaps to close the wound after removal of the tumor. The main trunk of the facial nerve and tracing it anteriorly, the marginal mandibular nerve were dissected. However, at the tail of the parotid, contrary to our expectations we noted that the tumor was totally free of the parotid gland. The tumor was dissected out by following the connective tissue planes around the tumor without incident. The specimen measured 22 × 20 × 11 cm and weighed 1.8 kg. Histopathology was consistent with diagnosis of a PA.
Discussion
Various subtypes of PPS tumors have been described and about 82% of these are benign, [2] 80–90% of these benign tumors are PA. PA arises mostly from deep lobe of parotid. A benign salivary adenoma arising de novo in the PPS independent of the deep lobe of the parotid is very rare. These develop from minor salivary gland of lateral pharyngeal wall or ectopic salivary rests in a lymph node or aberrant salivary tissue in the PPS. Among the tumors arising de novo in the PPS, the most common is the PA followed by the paragangliomas and the schwannomas [3]. PA of minor salivary glands is commonly located in the palate, lip, buccal mucosa, floor of the mouth, tongue and tonsil. Thus, even among minor salivary gland tumors, the de novo PPS salivary tumors are extremely rare.
PPS tumours manifests with painless mass in the neck or in the oropharynx causing dysphagia, dysphonia, feeling of lump in throat, cranial nerve deficits. On rare occasions they can present with obstructive sleep apnea or stridor [4]. Our patient had hardly any symptoms except for the swelling or those relating to the enormity of the swelling. A major problem that she had was difficulty in turning in sleep. She had to hold the tumor in order to change sides.
Imaging (CT, MRI) of neck are vital tools for the diagnosis which enable the operating surgeon to determine the extent of lesion, tumor type and plan of approach. The displacement patterns of fat and the internal carotid artery within the PPS aids in the localization of lesions. A primary PPS lesion is differentiated from an extension of a deep lobe parotid lesion by the presence of a fat plane between the parotid and the lesion. The orientation of the fat plane is also important. CT scans in our case could not reliably predict the tissue of origin as the fat planes around the tumor were obliterated radiologically due to the enormous size of the tumor.
The most frequent approach used to excise the lesions was the cervical approach (48%). We used a modified Blair’s incision modified with a double horizontal limb of the incision for better access to the tumor and its surrounding tissue and for quicker skin flap elevation. There was a lot of redundant skin which had to be excised anyway. Though the enormity of the tumor initially surprised us, pre-operative absence of any nerve palsies and the FNAC report of PA boosted our confidence in going ahead with surgery. In the end the surgery wasn’t too complicated as the tissue planes were clearly defined around the tumor resulting in an aesthetic post-operative result.
Review of literature in PubMed and Google shows that largest reported PPS pleomorphic adenoma is 12 × 10 cm, weighing 420 g [5].Other large reported PPS tumors include one measuring 10 × 8.2 × 5.8 cm [4] and another measuring 8.4 × 6.5 × 3.9 cm and weighing 87.3 gm [6].In our patient the tumor was 22 × 20 × 11 cm and it weighed 1.8 kg which is undoubtedly the largest among all reported cases. Highlighting the singularly large size of the tumors and its location in PPS with successful surgical management is the purpose of this article.
Authors contribution
Prof. (Dr). Indranil Pal—Unit head and headed surgical team. Literature search and collating information, editing. Dr. Usha G—Literature search, collating information and writing main article. Dr. Saumitra Kumar—part of surgical team, literature search, editing. Dr. Bibhas Mondal—part of surgical team, literature search.
Funding
No funding sources.
Compliance with ethical standards
Conflict of interest
Prof. Indranil Pal, Dr. Usha G, Dr. Saumitra Kumar, Dr. Bibhas Mondal declare that they have no conflict of interest.
Footnotes
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