Paraganglioma of the thyroid gland: cytologists' enigma.

Paraganglioma is a neuroendocrine tumour derived from extra-adrenal cells of the neural crest paraganglia of the autonomic nervous system. These rare neoplasms comprise of around 0.012% of head and neck tumours. Paraganglioma arising in the thyroid gland is exceptionally uncommon and can present as a diagnostic challenge on fine-needle aspiration cytology (FNAC). We report a case of primary thyroid paraganglioma in a 19-year-old woman who presented with a solitary thyroid nodule without palpable cervical lymphadenopathy. FNAC from the lesion caused diagnostic dilemma by mimicking follicular neoplasm and C-cell-derived thyroid tumours; final diagnosis was established by histopathology and immunohistochemistry. The main purpose of this case report is to discuss the differential diagnosis and emphasise on the need of immune markers in the diagnosis of thyroid paraganglioma. In view of the uncertain malignant potential of these tumours, a long-term follow-up is recommended.