eRadiograph Volume 7: Imaging of Oral Cavity | Page 230

superficial parotidectomy. WT may be treated with enucleation. Malignant lesions are
treated with a wide excision. If surgery extends deeper into the deep lobe or a total
parotidectomy is warranted the facial nerve is dissected and preserved. However if the
facial nerve needs to be resected due to local disease invasion, the facial nerve is
usually reconstructed by segmental reanastomosis or a interposition nerve graft.
Nodal spread occurs in high grade lesions and is an indicator of prognosis. Nodal
spread occurs in an orderly fashion- first intraglandular nodes then level 2/3 and
subsequently level 5A. Neck dissection is done for high histology grade tumors and
T3/4 lesions. Lesions with positive margins or high grade lesions receive post operative
radiotherapy. Salivary gland tumors have a high propensity for perineural spread
particulary adenoid cystic carcinomas. Spread may occur along mandibular division of
Vth nerve via the auriculotemporal nerve or VII nerve to the skull base. Perineurial
spread is visualised as widening of the neural foramen, thickening of the nerve,
enhancement of the nerve. The involvement may be contigous or have skip areas.
Distant metastases occur to the lungs, bones and liver. Adenoid cystic carcinoma has a
propensity for distant metastases similar to its propensity for perineural spread. Large
tumor size, high grade tumors, nodal disease, extraparenchymal extension are
predictors for distant metastatic disease.
There is a significant overlap between the imaging findings of benign and malignant
parotid lesions as a result FNAC is recommended preoperatively. This helps to
determine whether lesion is infective or neoplastic. Infective lesions can be treated
medically. Neoplastic lesions require surgery. Histopathology will help determine if
lesion is benign or malignant, this helps determine the extent of planned surgery,
based on this the patient can be counselled also re facial nerve involvement and
possible post operative complications. Also whether total gland removal is required
and the need for neck dissection.

Parotid Space

Post operatively patients are imaged to evaluate for any recurrent disease. Care must
be taken not to interpret post operative changes as recurrent neoplasm. These may
appear as illdefined areas of T2 hyper intensity and enhancement in the post operative
bed. There may be sialoceles post operative representing collections of saliva within
the gland following obstruction of the parotid ducts.

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