Meta-synthetic study on clear cell renal cell carcinoma (ccRCC) metastasis in the parotid gland and a case report of metastasis to parotid gland as a first sign of renal cell carcinoma

<ns3:p>Introduction: Renal cell carcinoma (RCC) ranks 14th among cancers developing worldwide. RCC is the most common solid lesion of the kidney and accounts for approximately 90% of all malignant kidney tumors. Metastases from RCC to the salivary glands are exceedingly rare, representing less than 0.1% of metastatic tumors in these glands. Distant metastases to the salivary glands are extremely rare. To date, there have been few papers analysing exclusively metastases of RCC to the salivary glands. A meta-analysis of the collected data was conducted, along with case presentation of a 68-year-old patient in whom the fine needle aspiration biopsy (FNAB) suggested a benign lesion. However, after a partial parotidectomy, the parotid gland tumor was identified as the first manifestation of advanced metastasis of clear cell renal cell carcinoma (ccRCC).Aim: The aim of this study was to analyse published cases of RCC metastasis to the parotid gland in the literature and to find out their characteristics.Material and methods: PubMed, Google Scholar databases were analysed using the words: ,,clear cell carcinoma‘ or ,,renal cell carcinoma’ or ,,renal cell carcinoma‘ and ,,metastasis’ or ,,metastasis’ and ,,parotid gland. The study was conducted according to PRISMA guidelines. A total of 356 articles were analysed, yielding 57 articles (1965-2023) meeting the inclusion criteria describing 69 patients with RCC metastasis to the parotid gland. Additionally, we presented a case of a patient treated at our clinic.Results: A meta-analysis of the collected data was performed. In all cases analyzed, the most common metastatic tumor to the parotid gland was clear cell renal cell carcinoma (ccRCC).Conclusions: Males are more frequently affected, with the lesion typically being painless and unilaterally located. Surprisingly, facial nerve paralysis at the time of tumor diagnosis is a rare symptom. Use for superficially located lesions, has a very low sensitivity in these cases. Therefore, FNAB in this context is non-diagnostic and carries a significant risk of false-negative results.</ns3:p>