A Case of a Metastatic Tumor to the Extraocular Muscles from Endometrial Carcinoma.

Orbital metastasis from endometrial cancer is rare. In particular, metastasis to the extraocular muscles has not been reported. Herein, we present a case of endometrial metastasis to the extraocular muscles. A 70-year-old woman presented with a history of endometrial cancer, with complaints of pain, proptosis, and swelling in her left eyelid. Since magnetic resonance imaging revealed a left orbital tumor, she was referred to our hospital. The tumor was 25 mm in size and was located in the inferior medial extraocular muscle. As the tumor had ring enhancement, and the patient was undergoing treatment for endometrial cancer, orbital metastasis was suspected. We performed tumor resection and orbital decompression by endoscopic endonasal surgery. The pathology results revealed metastasis from the endometrial cancer. After the surgery, her symptoms improved, and stereotactic radiation therapy was initiated. Although, treatment resulted in the shrinkage of the orbital metastasis tumor, the primary tumor progressed, and she died 4 months after her initial visit to our department. The endoscopic endonasal approach to extraocular muscle metastasis was minimally invasive and was effective in reducing pain. In addition, radiotherapy showed a marked effect on the residual tumor, suggesting that combination of these treatments was beneficial.