Microsurgery in primary tumours of the parapharyngeal space: observational retrospective analysis of a series of consecutive cases

Abstract

Objective: To investigate safety and efficacy of the microsurgical approach to parapharyngeal space (PPS) tumour. A secondary goal was to evaluate the correspondence between preoperative and final histopathologic diagnosis after surgery.

Methods: A consecutive series of primary PPS tumours treated between 1985 and 2022 in 2 tertiary referral centres with a microsurgical cervico-parotid approach was considered. The sample included 97 tumours (88 benign and 9 malignant) in 94 patients, of which 11 affected by recurrent tumours when first diagnosed at our centres. The surgical approaches, planned on the presumptive preoperative diagnosis, were pericapsular and en bloc resections (including either conservative or radical resections of the PPS).

Results: Pericapsular and en bloc resections of the PPS achieved complete removal in 88 out of 97 tumours. Relapses after PPS microsurgery occurred only in 8 cases (4 pleomorphic adenomas, 2 malignant schwannomas, one melanoma, and one haemangiopericytoma). Four of the 8 relapsed cases were recurrent cases when first seen at our centres. A complete correspondence between preoperative diagnosis and final histology occurred only in the group of benign lesions classified as paraganglioma, schwannoma, or lipoma, submitted to pericapsular resection.

Conclusions: Microsurgery may support the transcervical-parotid approach, by enhancing the operative space through narrow surgical corridors, improving dissection on critical cleavage planes, vessels and nerves, and allowing the exposure of both caudal and cranial extent of the lesions. In our series, pericapsular and en bloc resections of the PPS were effective in most of the included patients. In high-grade malignancies, where the morbidity of a wider resection beyond the PPS walls may include vessels and nerves, the indication should be accurately balanced.

Keywords: benign tumour; malignant tumour; microsurgery; parapharyngeal space; prognosis.

Cover figure.

Schwannoma of the left XII cranial nerve: A) appearance at MRI; B) same case, surgical view.

Figure 1.

Vagal paraganglioma at MRI: A) T1 contrast-enhanced sequence; B) T2 sequence.

Figure 2.

Deep lobe parotid pleomorphic adenomas at MRI: A) right side; B) left side.

Figure 3.

Recurrent parotid pleomorphic adenomas at MRI: A) right side; B) left side.

Figure 4.

Malignant schwannoma, right side, at MRI.

Figure 5.

Carcinoma ex pleomorphic adenoma, right side, at MRI.

Figure 6.

Recurrent sarcoma of the left PPS, at MRI.

Figure 7.

The clinical process from diagnosis to surgical approach in first diagnosis PPS tumours. PCR: pericapsular resection; CRPPS: conservative resection of PPS; RRPPS: radical resection of PPS; PA: pleomorphic adenoma.