Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) are two distinct neoplasms originating from follicular and parafolicular-C cells, respectively. These pathologies have always been considered different from each other in terms of their incidence, their cell origin and their histopathological features. Concurrent occurrence of MTC and PTC in the same patient is an unusual event and its occurrence as true mixed medullary-follicular-derived carcinomas is extremely rare.

Case report: We are presenting a case of 60-year-old man, with history of atrial fibrillation who was referred to an endocrinology consultation after diagnosis of thyroid nodules on cervical ultrasound. At neck examination, thyroid was palpable, without palpable thyroid nodules or cervical adenopathy. Ultrasonographically, a solid nodule with 22 mm (the largest dimension) located in the left lobe (in a multinodular thyroid gland) with irregular margins and microcalcifications; supraclavicular suspicious adenopathy was also noticed. The fine-needle aspiration (FNA) of the thyroid nodule suggested the possibility of medullary carcinoma. FNA of the supraclavicular adenopathy was compatible with medullary carcinoma metastasis. The serum calcitonin thus performed was elevated (428.5 pg/ml; NL: < 14.3), with normal urinary normetanephrines and metanephrines. Patient underwent total thyroidectomy with regional cervical lymph node excision. Histopathologically, the diagnosis of mixed medullary-papillary carcinoma of the thyroid was made, with papillary and medullary component metastases in 12 of the 38 isolated lymph nodes in left region and 8 of the 10 isolated lymph nodes at central region. He underwent ablative treatment with I131 and awaits Genetic consultation.

Conclusion: Mixed medullary-follicular-derived carcinomas are a very rare event in clinical practice, and there is a constant debate whether this event should be considered coincidental or rather the result of a common genetic alteration. It is of extremely importance to make the correct diagnosis due to its prognostic and treatment implications. For papillary thyroid carcinoma, radioactive iodine therapy and TSH suppression therapy may be recommended; the treatment of medullary thyroid carcinoma is essentially based on a radical surgical approach, requiring only levothyroxine replacement therapy. The genetic study of these patients is also pertinent to exclude multiple endocrine neoplasia type 2.