Molecular profiling of renal cell carcinoma presenting as iris metastasis

PURPOSE: To describe a case of iris metastasis as the initial presentation of clear cell renal cell carcinoma, and to discuss molecular profiling of both the metastasis and primary kidney tumor. OBSERVATIONS: We report a patient with blurred vision who underwent ophthalmic examination and was found to have an iris mass, which was excised and diagnosed as a metastatic clear cell renal cell carcinoma by morphology and immunohistochemical analysis. As a result of the pathology findings, computed tomography imaging was performed, revealing a right kidney mass, which was also resected and shown to represent a high-grade carcinoma confined within the renal fascia without lymphovascular invasion. Molecular testing of the primary and metastatic tumors using a custom next-generation sequencing panel revealed similar mutational profiles but disclosed a TERT promoter mutation in the primary neoplasm, not present in the metastasis, suggesting seeding of an early lower grade neoplastic cell clone within the iris. CONCLUSIONS AND IMPORTANCE: This report illustrates how pathological examination of a small iris lesion led to the discovery of a previously unknown systemic malignancy at a resectable stage. Molecular genetic profiling revealed that even lower grade clones within a high-grade neoplasm have metastatic potential.