Sclerosing polycystic adenosis

Sclerosing polycystic adenosis (also abbreviated SPA) is a rare salivary gland tumor first described in 1996 by Dr. Brion Smith.^[1] The major salivary glands, specifically the parotid gland (about 70% of cases) and the submandibular gland, are affected most commonly.^[2][3] Patients usually come to clinical attention with a mass or swelling in their salivary glands in the 5th decade of life, with females affected much more commonly than males.^[1][2] Nearly all of the cases reported so far have a benign behavior (no recurrence and no metastasis), although there is a single case that has had an associated malignant transformation (becoming an invasive cancer).^[4]

When reviewed by a pathologist, the findings are quite similar to fibrocystic changes of the breast, although they are different enough, that it is now recognized to actually represent a true neoplasm (clonal proliferation) through various studies.^[5] Specifically, the lesions are usually well-circumscribed, containing lobules of haphazardly arranged ducts, myoepithelial cells, and acini that have abundant sclerosing or hyalinized fibrosis. Apocrine change is quite common in the ductal cells.^[6] The ducts range from small ductules to cystically dilated spaces (more than 4 striated duct-widths across), often containing products of secretion or reactive histiocytes. A very curious and characteristic finding in all of the lesions is the presence of bright pink (eosinophilic) acinar granules (which are altered zymogen).