eRadiograph Volume 7: Imaging of Oral Cavity | Page 228

On imaging they appear as well defined lesions in the parotid whereas in the minor
salivary glands they appear as illdefined infiltrative lesions. They are of high signal
intensity on T2WI as they have a high water content. Adenoid cystic carcinomas have
the highest propenisity to extend perineurally of all head and neck cancers. Perineural
extension is seen much better on MRI as thickening of the nerve, enhancement on
post contrast. On CT there may be widening of the neural foramen with loss of fat
plane in the foramen. The most common nerves involved are the facial and
mandibular nerves.
Wide surgical resection with negative margins is treatment of choice with usually
adjuvant Radiotherapy – Adenocystic carcinomas have a high incidence of local
recurrenance, much higher than other salivary gland tumors.
Acinic Cell Carcinoma: Second most common malignant salivary gland neoplasm of
children and third most common bilateral salivary gland tumor after Warthins tumor
and pleomorphic adenoma in adults. The imaging features are non specific and often
diagnosed on FNAC or surgery.
Oncocytic Tumors: These may be benign or malignant – Benign tumors are 5 – 16
times more common than malignant oncocytic tumors. Imaging findings are
nonspecific. They present as solitary or multiple solid masses with sharp delinated
margins.

Lymphoma: Primary lymphoma of salivary glands is rare – if affected 80% occur in
the parotid gland. Primary lymphomas usually occur in the setting of pat ients with
auroimmune disease. The imaging appearances are nonspecific – a diffuse increase in
signal intensity and enhancement of gland similar to a chronic siladenitis.
The diagnosis is established by FNAC.
Secondary lymphomas of the parotid gland are more common than primary occurring
in 1- 8% of all lymphomas usually high grade diffuse large cell lymphomas. There may
be involvement of intraparotid lymph nodes which are enlarged or a diffuse
involvement of the parotid gland.
Metastases
The parotid gland contains intraglandular lymph nodes that drain the ipsilateral skin of
upper and mid face – basal cell CA, squamous cell CA, melanoma metastasize to

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Parotid Space

Neurogenic Tumors: Second most common benign mesenchymal neoplasm of
parotid space, Schwanommas are solitary, neurofibromas are multiple and usually
seen in association with NFI. Differentiating schwannoma from neurofibroma on
imaging is difficult. Neurofibromas arise from actual neuronal and perineuronal tissue
thus the nerve needs to be sacrificed at the time of excision. Schwannomas arise from
supporting neural elements, eccentric to the nerve therefore can be excised with
minimal drainage to the nerve.