Background: Intramedullary spinal cord metastases (IMSCM) are typically drop lesions from intracranial metastases and are a rare manifestation of systemic malignancy (8.5% of central nervous system metastases). They arise from primaries such as the lungs, breast, kidney, melanoma, or lymphoma. On the other hand, they arise very rarely from papillary thyroid carcinoma (PTC), even though it is the most common type of primary thyroid malignancy.
Case description: A 54-year-old male presented with pain in the lower back along with tingling, numbness, and weakness in the bilateral lower limbs. This was associated with urine incontinence for 1½ months. In the previous month, he developed a left-sided solitary thyroid nodule. Fine needle aspiration cytology and ultrasonography were suggestive of metastasis. Furthermore, the thoracolumbar magnetic resonance imaging showed T1-hypo and T2-hyper-intense D11-D12 level intramedullary lesion, with intense enhancement, which was consistent with an intramedullary lesion involving the conus. At surgery, a firm, brownish yellow, friable, vascular tumour was removed en toto. Upon discharge, the patient was neurologically intact except for residual bladder incontinence.
Conclusion: In an extensive literature review (pubmed), IMSCM metastasis from PTC primary is confirmed as a rarity and this may be the fourth documented case. Moreover, this may be the first report of a case of PTC metastatic neurological deterioration "even before the treatment of the primary was undertaken." Early diagnosis and microsurgical resection can result in improvement of neurological deficits and in the quality of life of patients with IMSCM.
Keywords: Intramedullary spinal cord metastasis; laminectomy; papillary thyroid carcinoma; spinal metastasis; thyroid cancer.