Case report: Tongue metastasis as an initial sign of clear cell renal cell carcinoma and its prognosis

Abstract

Clear cell renal cell carcinoma (ccRCC) is the most prevalent and lethal subtype of renal cell carcinoma (RCC), characterized by a poor prognosis and a high likelihood of distant metastasis. Nonetheless, metastasis of ccRCC to the tongue remains rare. Diagnosing and planning treatment for patients who initially present with tongue metastasis can be particularly challenging, as few cases have been reported in the literature. We present a case of a 62-year-old man who presented with a painful lump on the right anterior border of his tongue. Histological examination revealed lobulated and nested epithelial cell clusters with moderate dysplasia and frequent mitotic figures within the lamina propria. Immunohistochemistry showed positivity for vimentin, CD10, PAX-8, and epithelial membrane antigen (EMA), but negativity for PAX-2, calponin, S-100 protein, periodic acid-Schiff with diastase (PAS-D), P63, P40, and CK7, confirming the diagnosis of ccRCC metastasis to the tongue. After comprehensive evaluation and multidisciplinary team consultation, the patient underwent cytoreductive nephrectomy (CN), metastasectomy, and targeted therapy. According to the Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1, the patient maintained stable disease (SD) during systemic treatment. Unfortunately, treatment was discontinued due to adverse drug reactions, and the patient was transitioned to palliative care. His disease progressed to progressive disease (PD), and he ultimately succumbed to systemic infection, with a progression-free survival (PFS) of approximately 15 months. This case highlights the urgent need for improved therapeutic strategies to manage symptoms and prolong survival in patients with this rare metastatic presentation.

Keywords: clear cell renal cell carcinoma; cytoreductive nephrectomy; immunotherapy; metastasectomy; metastasis; targeted therapy; tongue.

Figure 1

A protruding bright red mass (red arrow) on the right front border of the tongue.

Figure 2

Hematoxylin and eosin staining of the tongue lesion reveals: (A) clusters of tumor cells located within the mucous membrane (red box) and submucosal layer, adjacent to the squamous epithelial tissue of the tongue (× 100); (B) tumor cells organized in clusters, supported by a dense capillary network (× 100); (C) tumor cells with large, hyperchromatic nucleoli (× 200); and (D) tumor cells exhibiting clear cytoplasm and pathological mitotic figures (red arrow) (× 400). Immunohistochemical staining results: positive staining for (E) vimentin, (F) EMA, (G) CD10, and (H) PAX-8, with negative staining for (I) PAX-2 (immunohistochemistry; E–I, × 400).

Figure 3

(A) Contrast-enhanced head and neck CT scan showing an unevenly enhanced lesion (red arrow) on the patient’s tongue. (B) Chest CT scan demonstrating spiculated nodules (red arrow) of varying sizes in both lungs. (C) Abdominal contrast-enhanced CT scan illustrating an irregular mass (red arrow) in the left kidney. (D) Size of target lesions (red arrow) in the lungs prior to treatment. (E) Size of target lesions (red arrow) in the lungs after 7 months of treatment, evaluated as stable disease (SD). (F) Following discontinuation of treatment, a new metastatic lesion (red arrow) appeared, and target lesions were evaluated as progressive disease (PD).

Figure 4

Whole-body PET/CT scan findings: (A) Soft tissue mass with ¹⁸F-FDG hypermetabolism in the left kidney (red arrow). (B) Soft tissue density lesion with ¹⁸F-FDG hypermetabolism at the right anterior border of the tongue (red arrow). (C) Multiple ¹⁸F-FDG hypermetabolic nodules and masses in the right lung (red arrow). (D) ¹⁸F-FDG hypermetabolic nodule in the left lung (red arrow).