Thyroglobulin as a Rapid and Cost-Effective Biomarker for Diagnosis of Thyroid Carcinoma Brain Metastasis: A Case Report of a Patient with Metastatic Hurthle Cell Thyroid Carcinoma

Specialty: Endocrinology Neurosurgery Objective: Unusual clinical course Background: Brain metastasis of papillary thyroid cancer (PTC) is rare. Treatment of these patients is challenging due to the lack of specific guidelines. Early diagnosis is accompanied by immediate treatment and less morbidity. Total resection of brain lesions may be unattainable when they include infiltration of eloquent areas. This report is of an 81-year-old man who had undergone total thyroidectomy for goiter in the past and presented with met-astatic papillary thyroid carcinoma (PTC) to the neck after a gap of 16 years. After two years, the patient de-veloped a solitary cystic brain PTC metastasis associated with raised thyroglobulin (Tg) inside the cystic lesion aspirated during brain surgery. Case Report: An 81-year-old male patient was admitted for a space-occupying brain lesion in the right frontal lobe. The pa-tient's history included metastatic disease of PTC to the neck with cervical lymph node metastasis and local recurrence after surgery and radioactive iodine-131 treatment. The patient underwent craniotomy and remov-al of the lesion. The aspirated fluid was sent for cytological examination and measurement of Tg levels, which were interestingly high. Pathology of the brain lesion revealed infiltration of brain parenchyma from a meta-static lesion characterized by eosinophilic cells with irregular contours forming grooves, resulting in cytoplas-mic pseudo-inclusions, an oncotic variant of PTC. Conclusions: This report has shown that residual tissue may be present following total thyroidectomy and may be the or-igin of PTC with metastasis to the brain. The patient in this study suffered from a brain lesion that could be excised. However, aspiration of cystic compartments could provide a rapid diagnosis in patients with non-re-movable brain lesions.