Co-existence of Papillary and Medullary Thyroid Carcinoma: Reports of Three Cases.

Medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) are two different types of thyroid carcinoma. They have different features in terms of cellular origin, histopathology, clinical features, prevalence, and prognosis. PTC originates from follicular cells, while MTC from parafollicular cells. MTC and PTC co-existence is a rare phenomenon and occurs in less than 1% of all thyroid tumors. We report three cases with coexistent MTC and PTC in the same thyroid. The papillary component was dominant in two cases and the medullary in one case. While the first case was given radioactive iodine therapy, the third was treated with vandetanib. The second case was followed up postoperatively and did not receive treatment other than levothyroxine replacement. The co-existence of these tumors requires a different clinical approach in treatment and follow-up, depending on which type is dominant. Key Words: Mixed thyroid carcinoma, Papillary thyroid carcinoma, Medullary thyroid carcinoma.

Control of Refractory Hypercalcemia with Denosumab in a Case of Metastatic Parathyroid Carcinoma.

Parathyroid carcinoma is a rare cause of hyperparathyroidism and leads to severe hypercalcemia. The etiology is not fully known. Parathyroid cancer should be considered in the differential diagnosis, if serum calcium and parathyroid hormone levels increase, and parathyroid gland is palpable. Severe hypercalcemia is the most common cause of death in patients diagnosed with parathyroid carcinoma. Fluid replacement, diuretic therapy, bisphosphonates, and calcimimetic agents are the main treatment steps in the control of life-threatening hypercalcemia. Surgery is the primary treatment option, while denosumab is a treatment option for refractory hypercalcemia caused by parathyroid carcinoma, or for patients who are not eligible for surgery. There are few case reports in literature about denosumab treatment for parathyroid carcinoma. Herein, we report a case of a patient who presented with the complaint of leg pain and was diagnosed with parathyroid carcinoma. The elevated calcium level of the patient was controlled with denosumab. Key Words: Parathyroid carcinoma, Denosumab, Hypercalcemia, Hyperparathyroidism.