Low-grade cribriform cystadenocarcinoma of the parotid gland: a case report.

Low-grade cribriform cystadenocarcinoma is a rare tumor that is recognized as a variant of cystadenocarcinoma by the 2005 WHO classification. We report a case of low-grade cribriform cystadenocarcinoma. The patient was a 32-year-old woman who presented with a mass in the right parotid region. Computed tomography and magnetic resonance imaging revealed a polycystic mass in the right parotid gland. The preoperative fine needle aspiration biopsy showed no malignancy, however the frozen section during surgery showed carcinoma. The patient subsequently underwent total parotidectomy with preservation of the facial nerve. Microscopically, the tumor had a typical feature of intraductal proliferation. There was a golden brown pigment and PAS-positive/diastase-resistant cytoplasmic granules in the epithelium of the cysts. Immunohistochemically, smooth muscle actin highlighted the cells rimming the cystic spaces. The tumor cells were negative for S-100 protein. The patient has no recurrence and no facial palsy after the treatment.