Parotid neoplasm: epithelial-myoepithelial carcinoma
Mass on right side of face.
MRI Face (Supra-hyoid neck protocol)
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A heterogeneous and lobulated mass replaces the deep lobe and much of the tail of the right parotid gland. This is slightly hyperintense to muscle on T1 weighted imaging and heterogeneously mildly T2 hyperintense compared to the normal glandular tissue. The anteromedial aspect points toward but does not clearly invade the parapharyngeal fat and posteromedially the digastric muscle and carotid vessels are preserved. Sternocleidomastoid also appears unremarkable posteriorly, as do the muscles of mastication anteriorly. No diffusion restriction within the lesion or adjacent lymph nodes. Ipsilateral lymph nodes are of similar size and morphology compared to those on the normal left side and there is no lymphadenopathy elsewhere within the neck. No evidence of perineural tumour spread, in particular, the facial nerve is unremarkable. A trace of fluid is noted within the right temporomandibular joint posteriorly, possibly reactive. No direct adjacent bony invasion. Incidental prominent tonsils are acceptable for age.
Conclusion: 3 cm heterogeneous mass involving the deep lobe and tail of the right parotid gland would be consistent with stated basaloid neoplasm. Although there are no definite imaging features of local invasion, perineural spread or nodal metastatic disease, carcinoma cannot be excluded.
Salivary glands have a large list of benign and malignant tumours, most of them without specific radiographic features and with the diagnosis made only on histology. In this case, histology revealed an epithelial-myoepithelial carcinoma, a rare malignant tumour that typically arises in a salivary gland and consists of both an epithelial and myoepithelial component.
They are predominantly found in the parotid gland and represent approximately 1% of salivary gland tumours.
Histologic differential diagnosis includes adenoid cystic carcinoma and pleomorphic adenoma.