Unexpected Cervical Lymph Node Metastasis Revealing TFE3-Rearranged Renal Cell Carcinoma: Intraoperative Cytologic Clues to an Occult Renal Primary.

TFE3-rearranged renal cell carcinoma (TFE3-rRCC) is a rare subtype of renal carcinoma that may present diagnostic challenges in cytologic specimens, particularly when metastatic disease represents the initial clinical manifestation. We report the case of a 72-year-old man presenting with bulky cervical lymphadenopathy clinically suspicious for lymphoma. Intraoperative touch imprint cytology from a level V lymph node demonstrated numerous discohesive and clustered epithelioid cells with abundant clear to granular cytoplasm, prompting reconsideration of a lymphoid process and appropriate tissue triage for histologic evaluation. Subsequent immunohistochemistry showed strong nuclear TFE3 expression with positivity for renal lineage markers, and RNA-based next-generation sequencing confirmed an SFPQ::TFE3 gene fusion. Imaging performed after pathologic diagnosis revealed an unsuspected renal mass. This case highlights the importance of recognizing cytomorphologic features suggestive of metastatic renal cell carcinoma during intraoperative consultation and underscores the role of cytologic evaluation in guiding diagnostic workup and tissue management in patients presenting with cervical lymphadenopathy of unknown origin.