Endocrine Abstracts

Introduction: Despite having different embriogenic origins, thyroid medullary carcinoma and follicular carcinoma may be seen together as mixed medullary-follicular thyroid carcinoma. We present a rare case of mixed medullary-follicular cell carcinoma of thyroid which has a progressive and aggressive nature.

Case report: A 68-year-old female patient admitted with complaint of a lump in her neck. Ultrasonography of thyroid gland revealed a 37×35 mm solid mass. Fine-needle aspiration biopsy was reported as ‘suspicious for papillary or follicular carcinoma’. Patient underwent total thyroidectomy and right selective neck dissection. Pathology report showed diffuse invasive follicular carcinoma. Tumor diameter was 5 cm and there was capsular and lymphovascular invasion. Patient received radioactive iodine (RAI) treatment. Posttreatment whole body imaging (WBI) revealed only postoperative residual thyroid tissue. Owing to discrepancy between increased thyroglobulin levels and negative WBI results, positron emission computerized tomography scan was obtained. Metastasis was noted between left lower pulmonary lobe and second lumbar vertebral body (L2) Vertebral metastasis was confirmed with magnetic resonance imaging The patient received radiotherapy to L2. However, she had a rapidly growing right cervical mass within 3 months. Neck CT comfirmed a 54×38×29 mm lymph node package. Owing to agressive nature and lack of improvement upon RAI treatment as suggested by lack of iodine uptake by metastatic lesions in WBI, pathologic specimens were re-evaluated. It was reported to be mixed medullary–follicular carcinoma. Tumor cells has been stained positively with carcinoembryogenic antigen, synaptophysin, chromogranin and calcitonin Excisional biopsy result of neck mass was reported as carcinoma infiltration. The patient received radiotherapy to neck mass and is still followed-up under thyroid stimulating hormone suppression.

Conclusions: In the presence of differentiated thyroid carcinomas resistant to RAI treatment and agressive and progressive nature, possibility of a mixed form carcinoma should also be considered.