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Abstract

Primary parapharyngeal space tumors are rare, and due to the complex anatomy of the parapharyngeal space, their diagnosis and treatment are challenging. Pleomorphic adenoma is the most common histologic type followed by paragangliomas and neurogenic tumors. They can present as a neck lump or an intraoral submucosal mass with the displacement of the ipsilateral tonsil or might be asymptomatic and discovered incidentally on imaging obtained for other reasons. Magnetic resonance imaging (MRI) with gadolinium is the imaging of choice. Surgery remains the treatment of choice and many approaches have been described. In this study, we present three patients with PPS pleomorphic adenoma (two primary and one recurrent), which were resected successfully with a transcervical-transparotid approach without mandibulotomy. Division of the following anatomical structures: the posterior belly of the digastric muscle, stylomandibular ligament, stylohyoid muscle and ligament, and styloglossus muscle is a very important tip for the surgeons because enables displacement of the mandible providing excellent exposure for complete tumor excision. The only postoperative complication was temporary facial nerve palsy in two patients who fully recovered within two months. The aim of this mini case series is to present our experience, together with some tips and benefits of the transcervical-transparotid approach for the resection of pleomorphic adenomas of the PPS.

Introduction

Primary tumors of the parapharyngeal space are not common, accounting for only 0.5% of all head and neck tumors [1]. Most of them, approximately 80%, are benign neoplasms [1]. The parapharyngeal space is a complex suprahyoid anatomical space, described as an inverted pyramid with the base formed by the skull base and the apex reaching the greater cornu of the hyoid bone. It is lateral to the pharynx and contains two compartments, the prestyloid and poststyloid compartment divided from the fascia running posteriorly from the styloid process to the tensor veli palatini muscle [2]. The prestyloid compartment is located anteriorly and contains fat, the retromandibular part of the deep lobe of the parotid gland, and lymph nodes. Most neoplasms in this compartment are of salivary gland origin. The poststyloid compartment located posteriorly contains many vital structures like the internal carotid artery, internal jugular vein, cranial nerves IX, X, XI, and XII, the cervical sympathetic chain, and lymph nodes. Tumors in this region can arise from each of these structures. Controversy exists among authors regarding what is considered a true parapharyngeal space lesion. It is not accurate to consider all deep lobe parotid tumors parapharyngeal lesions. Only tumors arising from the retromandibular part of the deep lobe should be considered of parapharyngeal origin. Likewise, only carotid body paragangliomas located above the posterior belly of the digastric muscle should be considered parapharyngeal space masses [3].

The differential diagnosis of benign PPS tumors includes pleomorphic adenomas of the salivary glands, which are the most common, followed by paragangliomas and neurogenic tumors [1]. PPS tumors usually present very few symptoms and are diagnosed only when they become large enough to be detected. More often they present as an intraoral smooth submucosal mass displacing the tonsil and the soft palate but sometimes, they can also appear as a neck...(More)

For more info please read, Resection of Primary and Recurrent Parapharyngeal Space Pleomorphic Adenomas via a Combined Transcervical-Transparotid Approach: A Case Series, by Cureus