Histopathological findings in parotid gland metastases from renal cell carcinoma.

Metastatic tumours involving the parotid gland arising from non-head and neck origin are rare. Immunohistochemistry has improved the differential diagnosis of these lesions. Current immunohistochemical markers allow the distinction between a number of potential primary tumours (e.g., lung, kidney and breast). We present the clinical and histomorphological features of three renal cell carcinoma (RCC) patients presenting with a parotid mass, review the literature of various non-head and neck malignancies metastasizing to the parotid gland, and discuss their differential diagnosis. Two females and one male, aged 58 to 76 years, presented with a parotid tumour of renal cell origin. In one case, the parotid mass was the first clinical manifestation. In the two other cases, a nephrectomy had been performed 5-9 years earlier because of RCC. The cases showed a highly vascular parotid lesion causing difficulty in interpretation of the fine needle aspirate. Two patients underwent a superficial parotidectomy and one patient an open biopsy of the parotid gland tumour. Immunohistochemical stainings for vimentin, CD10 and PNRA were positive suggesting renal cell origin, which was later confirmed. Clinical and radiological evaluations and diagnosis by fine needle aspiration may prove difficult partly due to the vascular nature of parotid metastasis of renal cell carcinoma. Immunohistochemical staining is useful in identifying the primary tumour.