Endocrine Abstracts

Background: Papillary thyroid cancer is a well-differentiated neoplasm and is the most common, accounting for 65–85% of all thyroid cancer. On the other hand, medullary carcinoma represents only 3–12%. The concurrence of distinct medullary and papillary carcinoma within the same thyroid has been sporadically described.

Case presentation: We report a rare case of simultaneous sporadic both multicentric medullary and papillary thyroid cancer with lymph node metastases in a 65 years old man patient. He presented with a one-month history of solitary right lobe thyroid node and watery diarrhea. He was biochemically euthyroid. Basal serum calcitonin levels was high. Diagnosis of medullary carcinoma was confirmed by positive aspirate immunohistochemical staining for calcitonin and negative thyroglobulin staining. Pheochromocytoma was excluded before operation. Patient was screened for the presence of the specific ret mutations. After total thyroidectomy and dissection of central lymph nodes, histopathological definitive examination of the speciment revealed medullary carcinoma in right lobe (4 cm), two distinct nodules of medullary (0.4 cm) and papillary (0.5 cm, with follicular components) carcinoma in the isthmus, papillary microcarcinoma (0.5 cm) in the left lobe and lymph node metastases of medullary cancer. All tumors were clearly separated from each other, representing the pure entity of each type. The postoperative course was uneventfull. Six months after operation he has no signs of progression of the tumour.

Conclusion: Medullary carcinoma derives from parafollicular cells or C cells of the thyroid. C cells have a neuroendocrine origin, being derived from ectodermal neural crest precursors. Papillary carcinoma derives from the follicular cells. This patient developed distinct histologic type tumors in separate lobes of the thyroid. This is the first report in which different synchronous both multicentric tumors type have been identified in one case. Although the simultaneous occurrence of papillary and medullary carcinoma may have been a simple coincidence, a common oncogenic stimulus may have been involved.