Gallego et al. Journal of Medical Case Reports 2011, 5:11 http://www.jmedicalcasereports.com/content/5/1/11 Page 2 of 4 Figure 1 A) Computed tomography image revealing a well demarcated mass in the anterior portion of the left parotid gland resembling a mixed tumor (red arrow). B) Histopathological image showing peri-neural invasion by the tumor and cohesive clusters of neoplastic cells (hematoxylin and eosin stain, original magnification 250×). C) High magnification image demonstrating oncocytic cells with abundant and finely granular cytoplasm and moderately pleomorphic nuclei located centrally or peripherally (hematoxylin and eosin stain, original magnification 400×). A month later, our patient underwent left superficial parotidectomy, including the removal of the mass. Because of clear infiltration of the tumor, the buccal branch of the facial nerve was resected. Macroscopically, the tumor was a well-circumscribed, firm, grey-brown, ovoid nodule measuring 2.5 cm in diameter. Microscopic examination revealed that the neoplasm had replaced a wide area of the parotid gland and peri-neural invasion was found (Figure 1B). The neoplastic elements were large, round or polyhedral cells and were arranged in solid sheets, islands and cords. The cytoplasm was abun- dant, eosinophilic and finely granular, characteristics indicative of oncocytes (Figure 1C). A diagnosis of OC was based on these histopathological findings and in par- ticular on the invasive growth pattern. We preferred a close follow-up to an elective neck dis- section, and reserved the neck dissection for a recur- rence, as there was no lymph node involvement either clinically or radiologically. Our patient was followed up accordingly, and four years after surgery started complaining of swelling and pain in the left cervical area. Physical examination revealed an elastically hard and poorly defined left cervical mass. There were no signs of local recurrence. FNAC showed oncocytes and atypical cells. A CT scan demonstrated several enlarged lymph nodes in the left parotid gland and on the left side of the neck (Figure 2A). Therefore, a complete par- otidectomy and radical neck dissection were performed. A microscopic examination of tissue samples confirmed that three lymph nodes were positive for metastases, as they had the same histopathological features as the pri- mary tumor (Figure 2B). Post-operatively there were no complications and no sign of recurrence after six months follow-up. Discussion OC is an extremely rare malignancy in salivary glands, accounting for just 0.5% of all epithelial salivary gland malignancies and 0.18% of all epithelial salivary gland tumors [5]. Criteria for the diagnosis of malignancy in