Irradiation-induced changes in human salivary glands.

Salivary tissue shows inflammatory changes, atrophy, replacement fibrosis, marked pleomorphism and atypia of the acinar epithelium and oncocytic metaplasia in the months following irradiation. The ductular epithelium undergoes squamous changes and within the ductular lumina, secretions become inspissated. The underlying pathogenetic mechanisms for these late irradiation induced changes may be the combination of a direct irradiation effect on acinar epithelium in association with post-obstructive inflammation and ischaemia, secondary to irradiation-induced endarteritis; however, these morphological changes observed may only be the result of an unusual repair phenomenon that salivary tissue is known to go through after any form of noxious stimulation. These histological alterations may lead to a possible misdiagnosis of malignancy in surgical specimens.