Salivary gland hyperplasia.

Thirteen cases of adenomatous ductal hyperplasia (ADH) of the major salivary glands coexisting with salivary gland tumors or chronic parotitis are reported. The proliferating ducts have the morphology and immunohistochemistry similar to intercalated duct epithelium. Adenomatous ductal hyperplasia is compared to adenomatoid acinar hyperplasia (AAH), a lesion found predominantly in intraoral salivary glands and histologically composed of hyperplastic acinar cells. The exact nature of both lesions is not clear. However, ADH may be a precursor lesion of salivary gland tumors (especially epithelial-myoepithelial carcinomas), whereas AAH may represent a reactive process of idiopathic nature.