Oncocytic carcinoma is a rare, predominantly oncocytic neoplasm whose malignant nature is reflected both by its abnormal morphologic features and infiltrative growth. Bauer and Bauer reported the first case in 1953. Although focal oncocytic features are seen in a wide variety of salivary neoplasms, both benign and malignant oncocytic neoplasms are extremely rare.
Clinical Features.
Oncocytic carcinoma may be considered to be a high-grade carcinoma. Most cases occur in the parotid gland but recent reports have described tumors that involved the submandibular gland and minor glands of the palate, nasal cavity, and ethmoid and maxillary sinuses. The average age of patients in one series was 63 years. Patients usually develop parotid masses that cause pain or paralysis. The skin overlying the gland is occasionally discolored or wrinkled.
Histologic Features.
All types of benign or malignant salivary gland tumors may have foci of oncocytic cells, but the oncocytic component usually contains such a small portion that it is unlikely to be confused with oncocytic carcinoma. Tumors with a significant oncocytic component include Warthin’s tumor, oncocytoma, and oncocytic carcinoma. They are characterized by oncocytes with marked cellular atypia, frequent mitoses, destruction of adjacent structures, perineural or vascular invasion, and distant or regional lymph node metastasis.
Histochemical or electron microscopic confirmation of the oncocytic (mitochondrial) nature of the cytoplasm is necessary because cytoplasmic accumulation of smooth endoplasmic reticulum, lysosomes, or secretory granules may have a similar appearance.
Treatment and Prognosis.
Oncocytic carcinoma is considered to be a high grade neoplasm and aggressive initial surgery seems to have a significantly better overall prognosis. Radiation does not appear to favorably alter the biologic behavior of this tumor. Prophylactic neck dissection may be indicated for tumors that are larger than 2 cm in diameter.