Metastatic renal cell carcinoma, clear cell type, of the parotid gland: a case report, review of literature, and proposed algorithmic approach to salivary gland clear cell neoplasms in fine-needle aspiration biopsies.

摘要

Renal cell carcinoma (RCC), clear cell type, is a commonly encountered metastatic tumor that can present at unusual anatomic sites many years after the primary tumor resection. Noncutaneous metastasis to the parotid gland is unusual; however, a number of cases of parotid RCC metastasis have been reported. Fine-needle aspiration biopsy (FNAB) is regularly utilized during the evaluation of salivary gland lesions, where it has a high sensitivity, specificity, and accuracy; however, the identification and definitive diagnosis of primary and metastatic clear cell neoplasms is a potential diagnostic pitfall for salivary gland FNAB. Here, we describe a case of RCC, clear cell type, metastatic to the parotid gland that was diagnosed entirely from FNAB cell block material, which is the first such reported case to our knowledge. We review the literature for cases of parotid RCC metastasis and focus on the utility of FNAB for synchronous versus metachronous presentations. Finally, we evaluate the differential diagnosis of clear cell parotid lesions, including ancillary histologic studies, and propose an algorithmic approach to clear cell neoplasms of the salivary gland.