Primary thyroid paraganglioma presenting with double thyroid nodule: a case report.

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• Paragangliomas (PGs) are rare neuroendocrine tumors originating from extra-adrenal chromaffin cells.
• Thyroid paragangliomas are exceptionally rare, with limited reported cases, posing diagnostic challenges.
• Differential diagnosis of thyroid PGs, both pre- and postoperatively, is often difficult due to overlapping features with other thyroid malignancies.

Observation:

• A 58-year-old euthyroid woman presented with multinodular goiter, initially suspected as medullary thyroid carcinoma (MTC) based on initial pathology.
• Surgical resection revealed nodules with features mimicking MTC, but immunohistochemistry was negative for MTC markers.
• Immunohistochemistry confirmed positivity for neuroendocrine markers (neuron-specific enolase, chromogranin A, synaptophysin) and S-100 protein, excluding thyroid differentiation.

Findings:

• The final diagnosis was thyroid paraganglioma, confirmed through extensive immunohistochemical analysis.
• Extensive laboratory and imaging workup ruled out metastasis and multiple endocrine neoplasia syndromes.
• This case represents the first reported instance of a thyroid paraganglioma presenting within a multinodular goiter.

Implications:

• Highlights the importance of comprehensive immunohistochemical evaluation for accurate diagnosis of thyroid PGs.
• Emphasizes the need for careful consideration of PGs in the differential diagnosis of thyroid nodules, particularly those resembling MTC.
• Underscores the diagnostic challenge posed by thyroid PGs due to their rarity and mimicry of other thyroid neoplasms.