INTRODUCTION: The diagnosis of metastatic iris tumor is made by a fine-needle aspiration biopsy of part of the solid component of the tumor and tumor cells seeded in the anterior chamber
however, sometimes the diagnosis is not made due to insufficient sample volumes. We report a case of metastatic iris tumor in which measurement of tumor marker levels in the aqueous humor together with fine needle aspiration cytology contributed to the diagnosis. CASE REPORT: An 80-year-old Japanese woman was referred to our hospital because of an iris mass. Six months before the initial visit, the patient was diagnosed with adenocarcinoma of the cecum. Slit-lamp microscopy revealed an elevated iris mass. Fine-needle aspiration cytology suggested adenocarcinoma. The carcinoembryonic antigen (CEA) level in the anterior chamber was 5,716.1 ng/mL, and serum CEA level measured on the same day were 678.5 ng/mL. These data indicated CEA levels synchronously elevated in both anterior chamber and serum. Based on aspiration cytology and high CEA levels of anterior chamber, she was diagnosed with metastatic iris tumor derived from adenocarcinoma of the cecum. One month after the initial visit, right eye irradiation was performed for metastatic iris tumor. CONCLUSIONS: Measurement of tumor marker levels in the aqueous humor, together with fine needle aspiration cytology of the tumor, contributes to the diagnosis of metastatic iris tumors.