Endocrine Abstracts

Introduction: Medullary thyroid cancer is a rare neoplasm, accounting for approximately 4% of all cases of thyroid cancer. Exceptionally, it can be associated with the hormonal production of ACTH or CRH, causing ectopic Cushing’s syndrome.

Clinical Case: We present the case of a 43-year-old man who, as a history of interest, presented a T6-T8 vertebral body fracture 2 years ago and a right hip fracture 1 year ago. Bone densitometry is compatible with osteoporosis. He began daily treatment with Teriparatide 20 mg subcutaneously, calcium carbonate 2.5 g and Cholecalciferol 800 IU. He was admitted to the hospital due to worsening pain. On examination he presented facial plethora, abdominal obesity, and muscular atrophy. Given the suspicion of Cushing, a blood test was performed, highlighting ACTH 114 pg/ml, Cortisol 43.2 μg/dl, Urinary free Cortisol in 24 h 516 mg, and 1 mg Dexametasone supression test 17 μg/dl. An MRI of the spine was performed and showed multiple medullary bone infiltration of the vertebrae and posterior costal arches. A CT scan of the chest showed pathological adenopathies in the upper mediastinum and an increase in the size of the thyroid with a nodular image in the right lobe. Abdominal CT showed both enlarged adrenal glands without observing nodulations. The study was completed with cervical ultrasound, where a 4 cm nodule in the right lobe with lobulated edges, heterogeneous echogenicity, and multiple adenopathies with a pathological appearance were observed. Fine needle aspiration was performed and confirmed the result of medullary carcinoma (Bethesda V). Blood tests showed Calcitonin levels of 8202 pg/ml and urinary Metanephrines were negative. Surgical intervention was performed by means of total thyroidectomy and central and lateral lymph node dissection, with the result in the biopsy of medullary thyroid carcinoma with lymph node involvement and positive immunohistochemistry for ACTH. We arrived at the diagnosis of medullary thyroid carcinoma with bone metastases, ectopic Cushing’s due to ACTH production originated in the medullary thyroid carcinoma. Treatment was started with daily Levothyroxine 150 mg on an empty stomach and Vandetanib 300 mg.

Conclusions: Medullary thyroid carcinoma is an uncommon cause of Cushing’s syndrome, but it is associated with high morbidity, as described in our patient. Those affected generally have a poor prognosis due to the presence of metastatic disease at the time of diagnosis, and on many occasions they have a large primary tumor mass with little probability of successful resection.