Cystadenoma of the palate: immunohistochemistry of mucins.

Cystadenoma is a relatively rare benign epithelial tumor of the salivary glands, and described herein is an additional case. A 51-year-old Japanese man had noticed a mass of the left hard palate 25 years previously. Macroscopically, the resected specimen was a multicystic lesion. Histologically, the tumor was composed of bilayered columnar epithelium with cystic change and partial solid growth of glandular structures with clear cells. The tumor cells had mild cellular atypia, but the tumor lacked papillary growth and a fibrous capsule. Immunohistochemistry was positive for cytokeratins, epithelial membrane antigen, MUC1, MUC4 and MUC6, but negative for myoepithelial markers, MUC2, MUC5AC and MUC5B. Such MUC expression patterns suggested that cystadenoma occurs from excretory ducts.