Endocrine Abstracts

Introduction: Medullary thyroid cancer (MTC) is a rare thyroid malignacy whоsе prognosis is highly dependent on the early diagnosis as well as on the available treatment options. Serum calcitonin represents the most sensitive test for the detection of MTC thus its measurement is strongly recommended in patients with known genetic or hereditary conditions associated with high risk of medullary hyperplasia or cancer. However, its diagnostic utility and routine clinical application in all patients with thyroid nodules are highly controversial especially in nodules less than 1 cm.

Case Description: Case 1: A 49-year-old woman was referred for further evaluation after finding increased levels of serum calcitonin on routine laboratory tests. Medical history and physical examination were unremarkable, the elevated levels of serum calcitonin were confirmed – 136.3 pg/ml. Neck ultrasound scan showed a solid hypoechoic lesion in the dorsal part of the right lobe measuring 7.6/4 mm in size with type 3 vascularization, no suspicious lymph nodes were detected. FNAB and calcitonin wash-out measurement were performed. Cytological report fell in BETHESDA III category, but calcitonin levels from the wash-out were > 5000 pg/ml, suggesting the lesion was medullary cancer. The patient was referred for surgery, histology and immunehistochemical analysis confirmed the diagnosis of a micromedullary cancer.

Case 2: The second patient is a 49-year-old woman in whom slightly elevated levels of calcitonin were found on occasion. She did not have any significant medical conditions, family history or medication intake. On neck ultrasound examination a 4.8/4 mm solid hypoechoic nodule in the ventral part of the right lobe was seen without any other abnormal neck findings. The cytological report from the FNAB was inconslusive but calcitonin wash-out measurement was >5000 pg/ml. Very small focus of medullary cancer was confirmed on histological and immunohistochemistry tests following surgery. Postoperative calcitonin measurement was negative, no abnormal neck lymph nodes were detected during follow-up.

Conclusions: MicroMTC is generally defined as a medullary cancer ≤ 1 cm in the greatest dimension and represents a rare entity with increasing incidence over the past decade. Calcitonin wash-out measurement can be a useful tool in the comprehensive evaluation of micronodular thyroid lesions. Early detection of medullary thyroid cancer significantly reduces the risk for local and distant metastasis and increases the rate of disease-free survival of the patients with this potentially lethal neuroendocrine malignancy.