Endocrine Abstracts

Introduction: Medullary thyroid carcinoma (MTC) is defined as a rare neuroendocrine tumor originated from the parafollicular C cells of the thyroid, noted for the ability of secreting calcitonin and other peptides. MTC poses a high risk of mortality if left untreated as the tumoral cells can invade nearby tissues, lymph nodes, lymphatic or blood vessels and, ultimately, other organs. Calcitonin is key in the evaluation and treatment protocol as its basal serum levels tend to be proportional with the tumor size and the extent of metastasis. Thus, targeted surgical treatment holds an important role in the therapeutic management of this disease. We present the case of a patient with low suspicion of MTC but with high suspicion of distant metastatic disease due to increased levels of serum calcitonin.

Clinical case: A 34 years old male patient, with a previous history of a ‘cold’ thyroid nodule in the left thyroid lobe and a serum calcitonin level of 1025 pg/ml with no significant clinical signs discovered during examination. Thyroid ultrasound described a solitary, hypoechoic, irregular macronodule in the left thyroid lobe with no suspicious lymph nodes. The family history was negative for MTC or MEN-related diseases. Fine needle aspiration biopsy confirmed the diagnosis and calcitonin wash-out level was higher than 200000 pg/ml, serum CEA levels of 56.56 ng/ml. Screening for primary hyperparathyroidism, pheochromocytoma and ectopic Cushing’s syndrome was negative. Germline RET mutation is awaited. The high level of calcitonin imposed additional imaging like cervical, thorax and abdominal computed tomography which revealed no evidence of local invasion, secondary lesions. The therapeutic decision was based on calcitonin levels and involved complete removal of the thyroid along with extensive prophylactic bilateral cervical lymph node dissection (central and lateral compartments). The results of the histopathological exam confirmed the diagnosis of CMT in the thyroid nodule but no affected lymph nodes. Seven days after surgery, the patient`s serum calcitonin levels dropped significantly to 4.35 pg/ml, with the CEA levels lowered to 29.13 pmol/l.

Conclusion: An optimistic prognosis of a patient with MTC is usually rare. Although an agreement on the subject of prophylactic lymph node dissections in the absence of secondary lesions does not exist, ultimately, the only chance of increasing the survival rate remains surgery. In this particular case with very high levels of calcitonin of an intrathyroidal CMT, a rapidly declining level of calcitonin after one-week post-surgery offers early evidence of remission.