Oncocytic carcinoma of the parotid gland: case report and review of the literature.

Abstract

To date 70 cases of oncocytic carcinomas (OCs) have been described in 55 reports. We describe an OC of the parotid gland in a 56-year-old man with simultaneous breast cancer.
In June 2006, a 56-year-old man was referred to the Otorhinolaryngology Division for a painless right preauricolar mass. The facial nerve was functionally normal. Total parotidectomy with facial nerve preservation was performed. In January 2007, the patient was referred to the Surgical Division for a left mammary nodule. Total mastectomy with axillary lymphoadenectomy was performed.
The mass of the parotid gland measured 3.5 x 3 cm. Histology showed sheets, islands and nests composed of large, round to polyhedral cells with fine, granular, eosinophilic cytoplasm and round vesicular nuclei, with prominent nucleoli. The tumour cells were positive for immunohistochemical staining with antimitochondria antibodies. Histological examination of the mammary tumour showed invasive ductal carcinoma Grade III (Nottingham Histologic Score) with metastasis in 12 axillary lymph nodes. Chemotherapy was performed. At present, the patient is free of recurrences or metastases.
Histologically, there is a spectrum of malignant parotid gland neoplasms that have prominent eosinophilic granular cytoplasm due to increased number of mitochondria. OCs have cytoplasm packed with mitochondria, while the term "oncocytoid" should be employed for tumours that have abundant eosinophilic granular cytoplasm, but ultrastructurally do not possess marked mitochondrial hyperplasia. All reported cases of OC should be defined "oncocytic-like carcinoma" when only haematoxylin and eosin staining is performed.