Follicular carcinoma of the thyroid is a well differentiated thyroid malignancy. It is usually slow growing and often tends to metastasize to distant organs by the hematogenous route. Bone and Lung are the most common sites of metastasis. Bone metastases are more often to the long bones. Metastasis to the skull is extremely rare, accounting for 2.5% of all bone metastases.
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We report the case of a 72-year-old female who presented to our neurosurgery service with only headache, nausea and gradually increasing scalp swelling over the past nine months. This large right sided fungating lesion was approximately 5 to 6 cm in length and was painless. It extended through the temporo -parietal bone with a contiguous large extra-axial intracranial component. The intracranial component had a mass effect on the subjacent temporal and parietal lobes. The patient was clinically euthyroid with normal general physical, systemic, and neurological examination. Neuroimaging findings strongly favored a diagnosis of meningioma. Craniotomy was performed and the tumor was debulked. Histopathological examination of the tumor showed it to be a metastatic follicular thyroid carcinoma. Ultrasound study of neck performed later revealed multiple sub centimeter cystic nodules with peripheral rim calcification in the right lobe of thyroid and a solid nodule approximately 1.5 cm in greatest dimension, with Grade III vascularity in the left lobe of thyroid. The patient was advised to undergo a total thyroidectomy followed by diagnostic and therapeutic I-131 whole body radioiodine scans. She elected to do so at another hospital closer to home.
This is a very rare presentation for such a large size metastasis. In previously reported cases of follicular thyroid carcinoma metastasizing to the skull, metastases predominantly occurred after diagnosis and treatment for primary cancer. Isolated skull metastasis from a well differentiated follicular thyroid carcinoma as the presenting feature is a rare manifestation and very few cases have been reported.
Westchester Medical Center
New Rochelle, New York
Current Endocrinology Fellow at Westchester Medical Center