SYNCHRONOUS ONCOCYTIC CARCINOMA, MEDULLARY CARCINOMA AND PAPILLARY MICROCARCINOMA OF THYROID.

Thyroid tumors are the most frequently reported endocrine malignancies. However thyroid collision tumors are rare pathological findings, representing less than 1% of thyroid cancers. In our case, a 50-year-old female patient presented with a complaint of neck swelling. During the exams, nodules were identified in both thyroid lobes. Pathologic analysis of a fine-needle aspiration biopsy(FNA) has been obtained from a 60×50 mm hypoechoic nodule raised suspicion of oncocytic carcinoma(OC). Another FNA was performed on a 17×11 mm hypoechoic solid nodule, revealing features of medullary thyroid carcinoma (MTC). Preoperative whole-body scans indicated no evidence of metastases. The patient subsequently underwent total thyroidectomy and central lymph node dissection. Pathological examination revealed OC, MTC, papillary microcarcinoma (PTMC), simultaneous metastasis of MTC and papillary thyroid carcinoma (PTC) to the same lymph node. The patient's calcitonin level was normalized postoperatively and I-131 ablation therapy was administered to the patient in the ATA high risk category. The patient was monitored under levothyroxine suppression. The simultaneous occurrence of OC, MTC and PTMC of the thyroid gland along with metastases of PTC and MTC in the same lymph node are reported in this case. To the best of our knowledge, this association had not been previously reported in the literature.