Rare metastasis in a patient with BRAF-mutated rectal cancer: choroidal metastasis - case report and literature review.

Purpose: Colorectal cancers are common and have high mortality, and metastasis is common in follow up. Choroidal metastasis is encountered rarely in rectum cancers, and there is no previous case reported from Turkey. We present our patient who developed choroidal metastasis in his cancer follow-up.

Case report: A 74-year-old male patient had undergone operation due to the diagnosis of rectum cancer two years ago, and lung (L) metastasis developed in the 4^th month after the adjuvant therapy, but he refused to receive treatment and remained out of follow-up. The patient presented with complaints of decreased vision and light flashes in his eye 21 months after the diagnosis.

Management and outcome: Ocular examination revealed a choroidal mass and radiologically choroidal and multiple brain metastases were detected. In our case, whole-brain radiotherapy was administered in the treatment since there were also multiple brain metastases. However, as the ECOG (Eastern Cooperative Oncology Group) performance status of the patient was 3-4 after radiotherapy, systemic treatment was not considered appropriate, and the best supportive care was given. The patient died 2 months after the diagnosis of choroidal metastasis.

Conclusion: Currently, there are few suggestions in case reports regarding appropriate treatment approaches for the treatment of rectal cancerchoroidal metastases. Multidisciplinary approaches may be effective for local and systemic treatment. Our case highlights a pathological entity with poor prognosis, which is rarely encountered during the course of rectal adenocarcinomas, and it is the first case of choroidal metastasis reported from our country. However, we believe that it will be important to draw attention to the fact that it is the first reported case of choroid metastasis in a rectal cancer patient with a BRAF V600 E mutation, and patients with BRAF V600 E mutation may develop metastasis to atypical areas due to their aggressive biology.