Primary clear cell carcinoma of parotid gland: Case report and review of literature
A female 88-year-old, presented with a gradual painless mass of 2 months duration in the right parotid region. There was no history of tumor elsewhere and her medical history was non-contributory. On palpation, a painful non-tender mass of about 3 cm was found. It was adherent to the skin and deep tissues. The facial nerve was not involved.\nA fine-needle aspiration was performed. Cytology revealed evidence of malignancy, with ductal and acinic cells suggestive of CCC. The analysis showed hypercellularity with large cells having enlarged nucleus and also multinuclear cells with a prominent and large nucleolus.\nComputed tomography (CT) scan showed a 2.8 × 1.7 cm solid poorly defined mass in the superficial lobe of the right parotid gland that hinted in the deep lobe []. Moreover, the mass was intensely and homogeneously enhanced with contrast and the structural appearance was that of a solid lesion of parenchymatose consistency with colliquative necrosis in the central areas. The cervical CT also revealed the presence of one metastatic cervical node with deep soft tissue and skin extension.\nOn the suspicion of a CCC, a full body CT was performed to rule out a renal tumor or metastasis, but it failed to show pathological results []. A diagnosis of primary CCC was thus made.\nModified functional neck dissection and radical parotidectomy with resection of the facial nerve was performed [Figure and ]. The facial nerve couldn’t be preserved because it was included in the tumor. The neck dissection included sternocleidomastoid muscle, spinal nerve and internal jugular vein, because they all were affected by the mass.\nHistology disclosed a non-encapsulated well defined tumor, though it had some infiltrating areas [Figure and ]. The mass was totally composed of cells with round central nucleus and abundant clear cytoplasm []. Pleomorphism was limited. No mitoses were found. Areas without clear cells were not observed. Additionally, one of the 34 isolated neck nodes was positive.\nTumor cells were negative for glycogen and mucin []. Immunohistochemical stains revealed that the tumor cells were positive for high-molecular-weight cytokeratins, carcinoembryonic antigen (CEA) [] and epithelial membrane antigen (EMA) and were negative for low-molecular-weight cytokeratins (CAM 5.2 and AE3), vimentin, S-100 protein, CK (cytokeratin) 7 and CK20. A posterior immunohistochemical study revealed that the tumor cells were positive for CD 10 (cluster of differentiation) [], which suggested the possibility of metastasis of renal clear cell adenocarcinoma.\nThe patient underwent postoperative radiotherapy and she was free from local or distant disease during 4 years of follow-up. Unfortunately, in 2011, an abdominal CT disclosed metastatic disease in the right lung, however no additional treatment was performed due to old age and poor health. The patient died a few months after that finding.