Oncocytic papillary cystadenoma of the parotid gland: characteristic multiparametric MRI signature

Oncocytic papillary cystadenoma is a rare benign epithelial neoplasm of the salivary glands, infrequently arising in the parotid gland. Its preoperative imaging characteristics are poorly described, and the diagnosis is often established only after surgical excision and histopathologic examination. We report two female patients (62 and 77 years old) who presented with parotid masses. Multiparametric MRI demonstrated multiloculated cystic lesions with distinctive features: (1) markedly low signal intensity (“signal void”) on T2-weighted and diffusion-weighted images with corresponding low apparent diffusion coefficient (ADC) values; (2) hyperintense signal on fat-suppressed T1-weighted sequences; and (3) minimal or absent enhancement of cystic components on post-contrast T1-weighted images, with enhancement confined to papillary projections. Facial nerve displacement without invasion was observed. Both patients underwent subtotal conservative parotidectomy with nerve preservation. Histopathologic analysis confirmed oncocytic papillary cystadenoma, and postoperative recovery was uneventful. The combination of T2/DWI signal void, fat-suppressed T1 hyperintensity, and post-contrast “vanishing” appearance is uncommon among parotid tumors and may represent a potential and previously underrecognized imaging feature of oncocytic papillary cystadenoma. Multiparametric MRI may reveal a potentially reproducible imaging pattern in oncocytic papillary cystadenoma, which, when interpreted in the appropriate clinical context, may assist in preoperative assessment and support nerve-sparing surgical planning; however, these observations are based on a limited number of cases and require validation in larger series.