Sclerosing Polycystic Adenosis of the Parotid Gland: Report of A Case with Multifocality

Sclerosing polycystic adenosis (SPA) is a rare tumor-like lesion of the salivary gland that bears a histomorphological resemblance to fibrocystic disease and sclerosing adenosis of the breast. The lesion is widely considered to be a pseudoneoplastic inflammatory process. However, foci of epithelial dysplasia and carcinoma in situ can occur in the lesion. We report a case of 16-year-old Thai female with multifocality of SPA arising in the right parotid gland. Grossly, the masses were well-circumscribed, firm, and whitish yellow discoloration with scattered small cysts. Microscopic examination revealed partially encapsulated masses composed of multiple irregular lobules containing cystically dilated ducts and foci of ductal and acinar proliferation embedded in sclerotic collagenous stroma. There were multiple foci of intraductal epithelial hyperplasia with focal cytological atypia. Immunohistochemical staining for calponin and smooth muscle actin demonstrated intact myoepithelial layer around each ducts and acini, which was an important clue in diagnosis this lesion.