Parapharyngeal space tumors: 61 case reviews

Abstract

Parapharyngeal tumors account for 0.5% of head and neck tumors. They are difficult to diagnose because they have few symptoms and are surgically inaccessible. This retrospective study included 61 patients with parapharyngeal space tumors, treated in the last 20 years. The data, obtained from the medical records, included symptoms and clinical signs, diagnostic procedures, surgical approach, postoperative complications and histopathological findings. The most common symptoms were dysphagia, foreign body sensation, pain, and symptom-free patients. For precise tumor localization and its relation to adjacent structures, computerized tomography, magnetic resonance imaging and contrast angiography were used. All the patients were treated surgically. The commonest surgical approach was transcervical, followed by transoral and combined transcervical–transoral. Histopathological examination verified that the origin of these tumors was most frequently salivary or neurogenic.

Tumors of the parapharyngeal space (PPS) are rare, accounting for 0.5% of all head and neck tumors. PPS tumors may be primary, metastatic or a direct extension of tumors from the adjacent spaces. The frequency of benign and malignant tumors is about 80% and 20%, respectively. Most of them originate from the salivary gland (40–50%), followed by a neurogenic etiology and the remainder are a broad spectrum of miscellaneous tumors .

The PPS is a lateral pharyngeal region. It is divided by muscular aponeurotic partition into an anterior (prestyloid) muscular compartment and a posterior (poststyloid) neurovascular compartment .

PPS tumors may be undetected for a long time, because they are not linked to symptoms. They are often presented as an asymptomatic growth and may be detected by regular checkup or as an accidental finding when scanning for another reason . Clinically, they are most frequently noted as a growth pushing the lateral wall of the oropharynx medially or a growth on the neck under the edge of the mandible angle. The symptoms are manifested when the tumor becomes larger than 2.5–3 cm .

The symptoms of PPS tumors are multiple and relate to the prestyloid–poststyloid localization, they include frequent foreign body sensation, difficult deglutition, otological symptoms and hoarseness. Clinical manifestations of PPS tumors are a mass in the oropharynx, a neck mass, cranial nerve deficit and Eustachian tube obstruction .

Imaging is crucial for the assessment of PPS tumors. Computed tomography (CT) with contrast medium, magnetic resonance (MR) and contrast angiography, in selected cases, are essential for diagnosis. Contrast CT is an effective imaging examination. MR is better than CT because it provides useful information on tumor localization and extent, and distinguishes tumors of the deep lobe, neurogenic lesions or intravagal paraganglioma or carotid body tumors and their relations with the internal carotid artery and adjacent structures . Angiography is recommended if paragangliomas or the involvement of the carotid artery is suspected .

Surgery is performed on the basis of information provided by these diagnostic modalities. Surgery of PPS tumors requires adequate exposure to identify and protect the anatomic vital structures. Several surgical approaches to PPS are described including transcervical, transcervical–transparotid, transcervical–transmandibular and transoral approaches, which are usually performed in these cases. All approaches have indications, advantages and disadvantages. The most common parameter for selecting a surgical approach is maximal exposure for complete tumor removal and preservation of the anatomic structures while minimizing functional and esthetic loss .

Materials and methods

This retrospective study included patients who had been diagnosed with PPS tumors and surgically treated from 1988 to 2007. The medical records were evaluated and analyzed. The data obtained was based on medical records, and included symptoms and clinical signs, diagnostic procedures, surgical approach and histopathological findings. This study involved 61 patients; all of whom were operated on by the same surgical team. All patients were clinically evaluated in detail. Neurological evaluation of the cranial nerves was also carried out. An audiogram was performed in cases with hearing disturbances.

The preoperative imaging diagnostics used were contrast CT and, recently, multi-slice CT (MSCT) and MR. In cases with a high suspicion of vascular tumor, angiography was applied. Analysis of the imaging methods revealed that the most important parameters determined were: localization of pre- or poststyloid tumor, relation to parotid gland, relation to major blood vessels and tissue characteristics of the tumors.

All patients in this study were treated surgically. The surgical approach was dictated by the localization of the tumor, its dimensions, relation to anatomic structures (carotid artery, jugular vein, cranial nerves) and suspicion of malignancy. Follow-up was carried out through clinical examination, chest radiographs, ultrasound of the neck, and CT scan of the head and neck where indicated (for all malignant tumors and for benign tumors with capsule rupture or tumor spillage). The median follow-up was 24 months. Data obtained from analysis of the medical history were statistically processed ( χ 2 -test). The objective of this study was to describe and analyze the symptoms and clinical signs of PPS tumors, the diagnostic procedures, surgical approach and histopathological findings.

Results

This was a retrospective analysis of PPS tumors in 61 patients (32 males; 29 females) treated primarily by surgery, whose mean age was 47 years (range 8–76 years). Patients who had undergone surgery for PPS tumors in other institutions and patients with other tumors were excluded from the study. The incidence and frequency of symptoms were analyzed ( Table 1 ). The most frequent symptoms were dysphagia (35%), foreign body sensation (21%) and pain (17%) ( Table 1 ). The incidence of asymptomatic patients was highly significant; in 14 patients an asymptomatic growth was detected during a routine checkup or accidentally while scanning for another reason. The difference between the incidence of three symptoms presented in Table 1 and other symptoms was highly significant ( χ 2 -test, Yates’ correction, χ 2 = 27.44, DF = 5, p < 0.01). The symptom that was not manifested was not considered.

Table 1
Incidence and frequency of symptoms.
Symptoms Total
N %
1. Dysphagia* 29 35
2. Foreign body sensation 17 21
3. Pain 14 17
4. Symptom free 14 17
5. Otological symptoms 5 6
6. Hoarseness 2 2
7. Dyspnea 1 1
8. Limited mouth opening 1 1
9. Symptoms of catecholamine excess 0 0.00
Total 83 100.00
χ 2 -test; p < 0.01.
The asterisk represents the most significant symptom.

The most frequent clinical signs were oropharyngeal mass (51%), neck mass (22%) and parotid mass (41%) ( Table 2 ). More frequent incidence of the first three signs from Table 2 was highly significant ( χ 2 = 61.77, DF = 4, p < 0.01).

Table 2
Incidence and frequency of clinical signs.
Signs Total
N %
1. Oropharyngeal mass* 46 51
2. Neck mass 20 22
3. Parotid mass 12 14
4. CN deficit 6 7
5. Pain on palpation 2 2
6. Unilateral Eustachian tube dysfunction 2 2
7. Obstructive sleep apnea 1 1
8. Horner Syndrome 1 1
9. Trismus 0 0.00
10. Catecholamine excess 0 0.00
Total 90 100.00
χ 2 -test; p < 0.01.
The asterisk represents the most significant clinical sign.

CT, MR and angiography were the diagnostic methods used. The frequency of CT and MR use was 70% (47 patients) and 21% (14 patients), respectively. Angiography was applied in 9% (6 patients). Data processing using the χ 2 -test showed a highly significant difference in the number of uses of CT compared with other diagnostic techniques ( χ 2 = 42.29, DF = 2, p < 0.01).

The surgical approach to the tumors is given in Table 3 . An external approach was most frequently used (transcervical, transcervical–transparotid, transcervical–transmandibular) in 62% (38), the transoral approach in 21% and combined approaches in 16%. The combined approach comprised a transcervical and intraoral approach without mandibular osteotomy and it was applied in larger tumors. The transcervical–transmandibular approach with mandibular osteotomy in the parasymphysial region was used in 3 cases with malignant tumors. Planned tracheotomy was performed in patients undergoing the transmandibular approach and in one patient undergoing the combined approach. One patient had a non-planned tracheotomy during wound management for a postoperative complication (hemorrhage). Ex tempore tumor analysis was carried out in 12 patients suspected of malignancy on the basis of CT or MR findings. The facial nerve was resected in one patient, which was not reconstructed due to advanced disease. The difference of the application of the external surgical approaches and other surgical approaches was significant ( χ 2 = 16.75, DF = 2, p < 0.01).

Table 3
Surgical approach to the tumors.
Surgical approach Total
N %
1. External
1. Transcervical 16
2. Transcervical–transparotid 19 38 62
3. Transcervical–transmandibular 3
2. Transoral 13 21
3. Combination (transcervical + transoral) 10 17
Total 61 100.00
χ 2 -test; p < 0.01.

Complications of surgical treatment were reported in 15 patients. Temporary paresis or paralysis of n. facialis (predominantly the marginal branch) was observed in 6 patients. Frey’s syndrome was seen in one patient but it gradually faded, unilateral paralysis of the vocal cords and hoarseness were noted in two patients, weakness of the hypoglossus in one patient as well as dysphagia in another, bleeding in one patient (within 24 h following the surgery); in addition, first bite syndrome was reported in two patients and trismus in one patient.

The results of histopathological analysis are presented in Table 4 . The incidence of salivary tumors was the highest (43%), the incidence of neurogenic tumors was 29% and that of other tumors was 28%. The incidence of salivary tumors and other types of tumors was not significantly different. Pleomorphic adenoma accounted for 21 tumors and neurilemoma for 13; together they accounted for over a half of all PPS tumors.

Table 4
Results of histopathological analysis.
Histopathology Total %
N %
Salivary
Pleomorphic adenoma 21 81
Basal cell adenoma 2 8
Adenocarcinoma 3 11
Total 26 100.00 43
Neurogenic
Neurilemoma/schwannoma 13 72
Neurofibroma 1 5.5
Ganglioneuroblastoma 1 5.5
Paraganglioma 3 17
Total 18 100.00 29
Miscellaneous
Metastasis
UCNT 1 6
Metastasis of neuroendocrine carcinoma 1 6
Metastasis of papillary thyroid carcinoma 1 6
Lymphoma non-Hodgkin 3 18
Sarcoma 2 12
Squamous cell carcinoma 3 18
Chordoma 1 6
Benign cyst 2 12
Benign lymph node hyperplasia 1 6
Hemangioma 1 6
Lipoma 1 6
Total 17 100.00 28
Total 61 100.00
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Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Parapharyngeal space tumors: 61 case reviews
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