Papillary cystadenocarcinoma: report of a case of high-grade histopathologic malignancy.

Papillary cystadenocarcinoma is an extremely rare malignant tumor of the salivary gland which is cytologically considered to be of low-grade malignancy, showing an indolent biological behavior. Histologically, the tumor is characterized by cysts and papillary endocystic projections. This tumor most commonly arises in the major salivary glands, mainly the parotid gland. We report here a case of papillary cystadenocarcinoma originating from the minor salivary gland, which showed marked growth over a short period of time. Histologically, the tumor was characterized by intense cellular and nuclear pleomorphism and numerous mitotic figures. These findings indicate a tumor of high-grade malignancy.