Primary Paraganglioma of the Thyroid Gland: Clinical and Immunohistological Analysis with a Literature Review

Primary paraganglioma of the thyroid is a rare neuroendocrine tumour, often mistaken for other thyroid neoplasms. Here, we describe a case of initially misdiagnosed primary paraganglioma of the thyroid and study its clinical presentation, management, investigation, and immunohistological findings.

A 72-year-old male presented with a left-sided solitary thyroid lobe and isthmus nodule. Ultrasound, fine needle aspiration, and computed tomography did not provide a clear diagnosis and subsequently, a left lobectomy and isthmusectomy were performed. The initial histopathological findings of the tumour revealed positivity to chromogranin and calcitonin, suggesting a medullary carcinoma replacing the left lobe of the thyroid. In a second histopathological review at an external laboratory, the tumour cells showed positive focal staining for chromogranin, but were negative for both calcitonin and monoclonal carcinoembryonic antigen, suggesting thyroid paraganglioma. This case highlights the importance of accurate histopathological diagnosis and the need to be aware of the possibility of thyroid paraganglioma initially presenting as a thyroid nodule.