Summary

Papillary thyroid carcinomas (PTCs), particularly microcarcinomas, rarely metastasise to the orbit. We report a case of a 49-year-old woman with a right supraorbital mass and unremarkable physical examination of the thyroid gland region. Orbital CT scan showed an expansile lytic lesion in the orbital plate of the frontal bone with a soft tissue component. An incision biopsy revealed metastatic well-differentiated thyroid carcinoma. Thyroid ultrasound was normal except for a subcentimetre nodule in the right lobe. The patient underwent total thyroidectomy where histopathology showed a subcentimetre follicular variant PTC. She subsequently received radioactive iodine therapy. Post-therapy whole body scan revealed metastatic thyroid tissues in the right orbital and posterior parietal, and left shoulder and hip areas. Although infrequent, metastatic thyroid carcinoma should be considered in patients with orbital metastasis even when neck examination is normal. In rare cases, this may be the initial manifestation of a widely metastatic papillary thyroid microcarcinoma.