A Case of Sigmoid Colon and Liver Metastases 14 Years after Surgery for Choroidal Malignant Melanoma

Abstract

A 64-year-old male patient underwent right eyeball enucleation for right choroidal malignant melanoma in 2008. He had no recurrence and the follow-up was already completed, but a pelvic mass was noted on a preoperative CT scan for percutaneous angioplasty for arteriosclerosis obliterans of the left lower extremity in December 2021. The tumor was suspected to be a submucosal tumor of the small intestine or sigmoid colon, and since it was less than 3 cm in diameter, the patient was followed up for observation. A CT scan conducted in April 2022 showed an increasing tendency of the tumor and intratumoral hemorrhage and surgical resection was performed for diagnosis and treatment. The tumor was black and adherent to the sigmoid colon and bladder, and multiple black masses were observed on the liver surface. The colon and bladder were partially resected in combination, and histopathological examination revealed a diagnosis of metastatic malignant melanoma of the sigmoid colon. The liver mass was later diagnosed as hepatic metastasis of malignant melanoma by EOB-MRI.

We report this case because choroidal malignant melanoma itself is a rare disease, and this is a rare case of metastasis after the completion of follow-up after surgery of the primary tumor.