Metastatic Renal Cell Carcinoma Presenting a Maxillary Mucosal Lesion as a First Visible Sign of Disease: A Case Report and Review of Literature

<b>Background and Clinical Significance:</b> Renal cell carcinoma (RCC) is the third most common cancer that metastasizes to the oral and maxillofacial region following breast and lung cancers. Metastatic involvement in the oral cavity is rare and can present as a diagnostic challenge due to non-specific clinical features that mimic other benign or malignant conditions. The limited information available regarding oral metastasis of RCC highlights the importance of recognizing this uncommon presentation. <b>Case Presentation:</b> A 50-year-old female presented with a painful swelling in the buccal and palatal mucosa of the right maxilla that progressively enlarged over several months. Initially, this lesion was diagnosed clinically as a pyogenic granuloma. However, given the lesion's continued growth and unusual presentation, a biopsy was performed. Histopathological examination confirmed the lesion as metastatic renal clear-cell carcinoma (ccRCC), with immunohistochemical analysis verifying the renal origin. Further diagnostic tests, including a computed tomography (CT) urogram, chest CT, and bone scintigraphy, revealed additional metastases in the left adrenal gland, lungs, and bone. <b>Conclusions:</b> This case is notable because the oral lesion was the first visible sign of RCC, making it a rare presentation of metastatic RCC. This underscores the importance of thorough history taking, detailed clinical evaluations, and considering rare metastatic conditions in the differential diagnosis of oral swellings. Additionally, this case reinforces the significance of routine cancer screenings for early detection of undiagnosed cancer. We also updated a previous literature review of metastatic RCC to the head and neck region, covering cases until 2023.