Case Report of a Primary Sinonasal Renal Cell-Like Adenocarcinoma With EWSR1 Gene Rearrangement in a 13-Year-Old Male

Background: Sinonasal renal cell-like adenocarcinoma (SNRCLA) is a rare, low-grade malignant neoplasm originating in the nasal cavity and paranasal sinuses. This report provides a detailed account of the clinical and pathological characteristics of a single case of SNRCLA, highlights its differential diagnosis, and includes a review of relevant literature.Case description: A 13-year-old male presented with a mass in the right nasal cavity. Histopathological analysis demonstrated tumor morphology analogous to clear cell renal cell carcinoma, characterized by abundant clear cytoplasm, acinar formations, and a prominent capillary-rich stroma. Immunohistochemical analysis revealed positive staining for cytokeratin pan, cytokeratin 7, vimentin, carbonic anhydrase IX, and SRY-box 10, with partial positivity for S-100. Markers such as paired box 8, atriopeptidase, renal cell carcinoma marker, melanosome, thyroglobulin, and thyroid transcription factor-1were negative. Fluorescence in situ hybridization analysis identified the presence of an EWSR1 gene rearrangement. The patient underwent surgical resection followed by adjuvant radiotherapy. Follow-up evaluations conducted as of November 2024 revealed no evidence of tumor recurrence, and the patient remained in good general health.Conclusion: SNRCLA is a rare neoplasm characterized by its low incidence rate and the necessity for exclusion-based diagnosis, requiring differentiation from other clear cell tumors. Immunohistochemistry plays a key role in establishing the diagnosis and distinguishing SNRCLA from histologically-similar entities. This case represents the first documentation of EWSR1 gene rearrangement in SNRCLA, thereby contributing novel insights into its molecular profile.