Presentation
Dysphagia and dyspnoea.
Patient Data
A large oval-shaped circumscribed soft tissue mass lesion is seen centred on the right parapharyngeal space posterior to the masticator space. It extends superiorly to the level of the skull base but has no intracranial extension and inferiorly to the level of C2. Medially, it is markedly compressing the oropharyngeal airway displacing it to the contralateral side. Posteriorly, it is encroaching on the right prevertebral space and mildly displaces the carotid sheath structures posteriorly. Laterally it is abutting the deep lobe of the right parotid gland. It displays a heterogenous high signal on T2WI and a heterogenous low to intermediate signal on T1WI with heterogenous post-contrast enhancement. There is no diffusion restriction.
The patient underwent surgical excision of the lesion, and the tumour was sent for pathology.
Pathology report:
Gross pathology:
Well-capsulated greyish white and yellowish firm nodular mass measuring 7 x 5 x 3.8 cm, containing a small muscular tissue at the lower part of the mass measuring 1.7x1.6 cm.
Microscopic picture:
Examinations of sections revealed a nodular tumour formed of sheets of myoepithelial cells admixed with glandular structures displaying eosinophilic secretion. Myxoid and myxochondroid areas were detected admixed with myoepithelial sheets. The mass was completely surrounded by a fibrous capsule showing defects, from which tumour tongues were protruding, yet the free outer aspect of the specimen was consistent with complete excision. A peripheral rim of unremarkable salivary tissue was observed in some parts.
No malignancy could be detected in the sections examined.
Conclusion:
Right huge parapharyngeal mass, excision biopsy
Pleomorphic adenoma (benign mixed salivary tumour)
Free outer capsule (completely excised)
No malignancy in the sections examined
Case Discussion
When a parapharyngeal mass is large, it can be difficult to determine its source. In this case, the pathology confirmed that the mass was a pleomorphic adenoma, either originating from the deep lobe of the right parotid gland or from a minor salivary gland rest within the parapharyngeal space.
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