Case report reveals atypical immunohistochemical profiles in endolymphatic sac tumors, indicating standard marker panels cannot reliably rule out metastatic renal cell carcinoma.
Key Points
To report atypical immunophenotypes in endolymphatic sac tumors and assess the diagnostic reliability of standard immunohistochemical panels used to distinguish them from metastatic renal cell carcinoma.
Evaluated immunohistochemical expression profiles (including PAX8, CA9, CD10, and RCC) in two patients presenting with endolymphatic sac tumors.
Performed whole exome sequencing on one patient's tumor to assess for von Hippel–Lindau (VHL) gene alterations alongside clinical and radiologic examinations.
Identified one endolymphatic sac tumor positive for PAX8, CA9, and RCC (negative for CD10), and a second tumor positive for PAX8 but negative for CA9.
Detected no VHL mutation on whole exome sequencing in the CA9-negative tumor, and confirmed absence of renal masses on imaging at diagnosis and follow-up in both patients.