Endocrine Abstracts

Primary Paraganglioma of Thyroid Gland is an extremely rare neuroendocrine tumor. Less than 50 cases have been reported up to date and its rarity is the reason why it’s often mistaken for thyroid nodule or other thyroid neoplasms. In this case we describe the misleading results of ultrasonography followed by FNA-biopsy, which led to a total delay of two years until final diagnosis. A 60 year old female presented with a 38 mm right-sided thyroid module. An ultrasound guided FNA-biopsy was performed and the cytology report was suggestive of a follicular adenoma. A total thyroidectomy was suggested because of the large size and hyper vascularity of the nodule, which was performed two years after initial examination. The results of histological examination revealed a neoplasm morphologically following a nesting pattern (zellballen) with rich capillary network. Immunohistochemical staining of the neoplasm was positive for chromogranin, synaptophysin and CD56. Sustentacular cells were positive for S-100 and Ki-67 was lower than 1%. Staining was negative for thyroglobulin and calcitonin. Neck-adrenal MRI as well as chest CT were normal. She underwent blood tests for gastrin, chromogranin A, calcitonin, tumor markers and 24 h catecholamine urine test (CATU) along with 5HIAA and VMA, all of which were also normal except from chromogranin A: 487 ng/ml (normal values: <120 ng/ml). We have no evidence of recurrence up to date and we suggested to the patient to undergo molecular analysis for germline mutations of the genes encoding succinate dehydrogenase subunits, SDHD, SDHAF2, SDHC, SDHB and SDHA. Diagnosis of TP is always confirmed postoperatively and differential diagnosis also includes medullary thyroid carcinoma and hyalinizing trabecular adenoma. These three conditions need completely different surgical approach and a close post-operative follow-up testing. Despite its rare frequency thyroid paraganglioma should always be included in the differential diagnosis of hypervascular thyroidal lesions especially those with indeterminate or undefined cytological results.