Case Presentation: A 69-year-old male with a history of bronchitis, colon polyps, and obstructive sleep apnea was admitted to the hospital for diarrhea and syncope with a low hemoglobin level of 8.4 and a cervical spine fracture. During his hospitalization, the patient noted a “lump” on his superior left tongue that he had first noticed after a dental appointment two months prior along with fatigue, appetite loss, tongue discomfort, and friability with oral intake. On physical exam, an 8 mm x 8 mm x 8 mm papule was noted on the tongue with central beefy red tissue and a circumscribed, light, fibrinous border which was non-tender, firm to the touch, with no active bleeding or notable ulceration. The patient was evaluated by otorhinolaryngology on his sixth day of hospitalization for a differential diagnosis that included neoplasm, pyogenic granuloma, atypical mucocele, or fibroma. The patient underwent a biopsy which showed tumor cells positive for PAX8 and CD10 and negative for p40, S100, p63, and RCC. The features of the biopsy were consistent with metastatic Renal Cell Carcinoma, favoring clear cell type. CT of the chest, abdomen, and pelvis with contrast showed a multilobulated mass in the left kidney without evidence of lymphadenopathy. Additionally, it showed pulmonary nodules in the left upper lobe and right lower lobes concerning for pulmonary metastasis and bilateral adrenal gland mass lesions with the right lesion concerning for metastasis from the kidney. MRI of the brain showed no evidence of intracranial metastasis with possible evidence of metastasis in clivus, C1, and C2 vertebral bodies. The tumor was staged at IV with a goal of palliative care and a recommendation to begin nivolumab (NIVO) plus ipilimumab (IPI) chemotherapy.

Discussion: Renal Cell Carcinoma (RCC) accounts for 3-5% of all cancer diagnoses in adults, with over 50% of RCC cases diagnosed incidentally (3). The classical presentation includes gross hematuria, flank pain, and a palpable abdominal mass (3). Rarely, manifestations of RCC can occur as tongue metastases (6). Although RCC is the third most common tumor to metastasize to the head and neck (1), we are only aware of 51 reported cases of tongue metastasis (2). Of those cases, only 7 include tongue metastasis as an initial presentation (2). To our knowledge, this case represents just the 8th documented incidence of tongue metastasis as an initial presentation of RCC. For patients with stage IV RCC, surgical treatment is not curative and treatment options include combinations of immunotherapy plus VEGFR inhibitors, immunotherapy with NIVO plus IPI, lenvatinib plus pembrolizumab, or NIVO plus cabozantinib (4). New therapies have improved the prognosis for metastatic disease, although the five-year survival rate for stage IV RCC is only 8% (5).

Conclusions: Diagnosis of RCC can be made difficult when the classic symptoms of gross hematuria, flank pain, or palpable abdominal mass are not present. Patients presenting with lesions of the tongue should raise concern for possible primary or metastatic malignancy, with primary malignancy being significantly more common than metastasis (2). This case highlights the necessity to investigate new-onset tongue lesions for underlying malignancy.