Background: Differentiated thyroid cancer (DTC) carries very high overall 10-year survival rates, 93% for papillary carcinoma and 85% for follicular carcinoma.1 The presentation of distant metastases drastically reduces these rates but distant metastases at diagnosis is uncommon.2 Furthermore, DTC presenting initially with distant metastasis is even more uncommon, accounting for only 2% of thyroid cancer cases.3
Case Report: An independent 89-year-old female from home alone presented with lower limb weakness and left foot drop. She described progressive gait disturbance over 4 months and development of urinary urge incontinence. Examination revealed bilateral lower limb weakness and reduced ankle and knee jerk reflexes bilaterally. MRI spine showed a large mass involving the posterior elements of T10 resulting in compression of the thoracic cord and cord oedema. She was commenced on high dose steroids. She underwent excision of the large extradural tumour, partial T10 vertebrectomy and T9-11 laminectomy and fusion. The tumour histopathology was metastatic follicular thyroid carcinoma. Further investigation with thyroid ultrasound revealed a multinodular goitre including a left lower pole 22mm nodule, TIRADS 4. There was no neck lymphadenopathy. On FDG-PET this thyroid nodule was mildly FDG avid, SUV max 3.3. Nil other metastatic disease was identified. FNAB of the nodule confirmed thyroid carcinoma. Further treatment including total thyroidectomy followed by radioactive iodine was discussed. Due to the patient’s age and functional decline she opted for no further treatment.
Discussion: The presence of distance metastases drastically reduces the 5 year survival rates of DTC to 77.6% for single organ metastasis, and 15.3% for patients with multi-organ metastases.[2] Our case demonstrates a rare presentation of spinal cord compression as the initial presentation of DTC. The best management approach of such patients is not clear given the rarity of these cases, but thyroidectomy to facilitate radioactive iodine therapy is usually recommended.4