ODP466 Case of Sporadic Medullary Thyroid Cancer Detected by Serum Calcitonin Measurement

INTRODUCTION: Thyroid nodules are common and their prevalence has increased with more widespread neck sonography. While most thyroid nodules are benign their evaluation and surveillance is centered around identifying nodules that harbor malignant growths. While secular trends suggest progressively increasing prevalence of thyroid cancer, it is largely an indolent generally curable disease. Medullary thyroid cancer (MTC) is comparatively rare (3-5% of all thyroid cancer) and significantly more virulent than the common papillary thyroid cancer. Guidelines regarding screening for potential MTC remain controversial. We describe the case of a patient with sporadic MTC detected by routine serum calcitonin measurement. Clinical case; The patient is a 52 yr old Caucasian man referred after a serendipitous finding of thyroid calcifications found on Neck and Chest CT done for radiculopathy evaluation. He had no neck symptoms and no anomalies on clinical neck examination nor history of radiation exposure nor relevant family neoplastic history. The neck ultrasound showed a multinodular goiter with a dominant hypoechoic 1.4 cm nodule in the right hemi-thyroid with microcalcifications (TIRADS 5). The nodule biopsy showed pauci-cellular specimen with abundant colloid and the patient had opted for repeat serial sonography rather repeat biopsy because of his unpleasant experience with the first biopsy. Routine initial endocrine evaluation included thyroid function tests (normal) and a random serum calcitonin; 267 (n; <15pg/ml). This degree of elevation was confirmed on repeated measures. A calcitonin stimulation test with calcium gluconate showed a peak stimulated calcitonin of 786 pg/ml. Total thyroidectomy and central neck dissection, confirmed a diagnosis of MTC (T1a N1a Mx). Only one of six sampled neck lymph nodes showed metastatic disease. RET mutation testing was -ve and 4 months post surgery his calcitonin is 97pg/ml with no radiologic evidence of any residual or recurrent disease. DISCUSSION: The patient's clinical presentation is typical of sporadic MTC (found serendipitously) which while uncommon is more prevalent than familial MTC and has a significantly more virulent clinical course than the much more prevalent classic papillary thyroid cancer. It also has significantly less cure potential and greater morbidity and mortality risk making early detection and aggressive management even more vital. Despite not being included in many guidelines for standard evaluation of thyroid nodules the random calcitonin obtained in the patient was central to the prompt and correct diagnosis of the patient. CONCLUSIONS: Despite the limitations and caveats to its interpretation, our case highlights the potential utility of routine serum calcitonin measurement as part of the routine screening work up of thyroid nodules even in so called "low risk" clinical presentations with no clinical flags suggestive of possible familial MTC or MEN 2. Presentation: No date and time listed