Asian Oncology Research Journal

Introduction: Metastasis of renal cell carcinoma (RCC) to the oral cavity is uncommon but clinically significant and often presents with non-specific features resembling benign or reactive oral lesions. In some patients, the oral lesion may be the first clinical manifestation of an undiagnosed primary renal malignancy, making early recognition essential.

Objective: To systematically evaluate the demographic characteristics, clinical presentation, anatomical distribution, histopathological findings, diagnostic methods, treatment modalities, and outcomes of renal cell carcinoma metastasis to the oral cavity.

Methods: This qualitative systematic review synthesised evidence from published case reports and case series without meta-analysis. A comprehensive literature search was conducted in PubMed, Google Scholar, and ScienceDirect for English-language studies published between 2010 and 2025 using Medical Subject Headings (MeSH) and free-text search terms. Titles, abstracts, and full-text articles were screened according to predefined eligibility criteria. Data were extracted using a standardised form, and methodological quality was assessed using the Joanna Briggs Institute (JBI) critical appraisal tools.

Results: A total of 18 studies comprising 20 patients met the inclusion criteria. Most patients were male and were in the fifth to seventh decades of life. The tongue was the most frequently affected site, followed by the gingiva and jawbones. Lesions commonly presented as rapidly enlarging, highly vascular, ulcerated masses, often mimicking pyogenic granuloma and other benign oral lesions. Histopathological examination most frequently demonstrated the clear cell subtype, characterised by nests of clear cells within a rich vascular stroma. Immunohistochemical expression of paired box gene 8 (PAX8), cluster of differentiation 10 (CD10), and vimentin supported diagnostic confirmation. Surgical excision was the most commonly employed treatment, although the overall prognosis remained variable.

Conclusion: Renal cell carcinoma metastasis to the oral cavity should be considered in the differential diagnosis of unusual oral lesions. Histopathological examination combined with immunohistochemistry is essential for accurate diagnosis and prompt identification of the primary malignancy. Because the findings are derived from published case reports and case series, they should be interpreted in light of the inherent limitations of this level of evidence.