Orbitotemporal Bone Cyst of Metastatic Breast Cancer: Case Report and Literature Review

Metastatic breast cancer in the bone rarely has a cystic appearance, and while it is common in the orbit, its metastasis to the orbitotemporal skull is rare. Consequently, it is difficult to diagnose it. We report and discuss a rare case of metastatic breast cancer with simple cyst appearance in the orbitotemporal region of the skull. A 63-year-old woman presented with mild double vision only on left gaze that lasted for 2 months. Ten and a half years ago, the patient underwent surgery for tumor resection of a stage 3 breast adenocarcinoma, followed by radiotherapy and administration of anticancer therapy. Thereafter, she continued hormonal therapy with antiestrogen drugs, which was discontinued a half year ago because there was no recurrence during treatment. On admission, magnetic resonance imaging (MRI) showed a single and simple cystic lesion in the orbitotemporal region of the skull. The cyst was filled with fluid of different intensity, indicative of a hemorrhagic component. Additional gadolinium-contrasted MRI showed no enhancing effects in the lesion. The cyst was totally removed by surgery, and the histologic examination confirmed the diagnosis of breast adenocarcinoma. Intensity-modulated radiotherapy was then administered, and the patient started follow-up hormonal therapy with antiestrogen agents. No recurrence in the orbitotemporal region of the skull occurred during 6 months after the surgery. Metastatic breast cancer should be considered in the differential diagnosis even if it appears as a simple cyst in the orbitotemporal bone after long-term remission.