Mixed papillary and medullary thyroid carcinoma

Mixed Papillary and Medullary Thyroid Carcinoma: A Case Report Mixed medullarypapillary thyroid carcinomas are rare tumors. On routine examination, a 50- year- old woman was found to have a thyroid nodule. Ultrasound (US) reveald a bilobate gland of normal size, with a nodule 10 mm in greatest diameter in the lower part of the right lobe. Hormone analysis showed euthyroidism. The routine percutaneous US- guided fine-needle aspiration (FNA) was performed using 22- gauge needle. The aspirate was smeared and stained routinely. The FNA showed abundant cellularity with follicular and papillary structures. In addition, other population of tumor cells were pleomorphic, large, with occasional binucleation and multinucleation, coarse chromatin and prominent nucleoli in clusters and singly. The intranuclear cytoplasmic invaginations were found in some cells. The cytological diagnosis of the dedifferentiated carcinoma was made and surgical treatment was recommended. The hystological diagnosis was mixed papillary and medullary carcinoma based on immunohystochemical analysis. The pleomorphic cells were calcitonin, TTF – 1, CEA, chromogranin synaptophisin and Ca 19, 9 positive. The cells with INCI („ ground glass“ nuclei) were thyreoglobulin positive. The presence of both medullary and papillary components is rare and may suggest that the tumor had arisen from a common stem cell. A case of mixed medullary, papillary, follicular and undifferentiated pattern of thyroid carcinoma also has been reported.