Diagnosis of Medullary Thyroid Cancer During COVID-19 Pandemic, the Benefit of Using a Standardized Protocol

Abstract

Abstract Introduction: The reported prevalence of malignancy in thyroid nodules ranges from 4% to approximately 10%, with a small percentage (~2-8%) being medullary thyroid cancer (MTC). During the COVID-19 pandemic, elective thyroid FNA was temporarily halted at our institution. In response to this, our institution has devised a new protocol to aid in the detection of MTC, which includes serum calcitonin measurement as a surrogate marker for potential MTC. A severely elevated calcitonin (>100 pg/mL) is considered for surgery even without FNA diagnosis. We present a case of MTC that was detected due to the adopting of this protocol during COVID-19 pandemic at the Phoenix VAMC. Case Presentation: 71 year old male with an incidentally noted 3.0 cm solid, hypoechoic nodule with internal calcification, TI-RADS category 5. TSH level was normal at 3.309 mIU/mL. The patient denied any personal or family history of thyroid cancer, MEN syndrome, radiation exposure, or compressive symptoms. Following established protocol published by our institution in clinical thyroidology we performed a serum calcitonin that came back elevated at 1515 pg/mL (normal < 10 pg/mL). Given the marked elevation in serum calcitonin levels and highly suspicious radiographic appearance of the thyroid nodule, we strongly suspected medullary thyroid cancer and elected to send him directly for total thyroidectomy without performing FNA. The patient underwent total thyroidectomy with central neck dissection. Pathology showed a 3.2 cm medullary thyroid carcinoma without extrathyroidal extension or perineural invasion. Lymphovascular invasion was present. 6/10 central comparement lymph nodes were positive for metastatic disease. Postoperative calcitonin level was 2 pg/mL. Discussion: Our patient had markedly elevated serum calcitonin levels in addition to a high-risk ultrasonographic features, which was highly suspicious for MTC. Per our COVID-19 protocol, we measured the serum calcitonin level to screen for MTC and then referred him directly to surgery without FNA given the high suspicion for MTC. By using this protocol, we were able to diagnose and treat MTC expeditiously. The measurement of serum calcitonin is still controversial in the U.S, with the ATA remaining equivocal on this method. We believe that our case can serve as a practical example that validates our institution’s use of calcitonin screening of thyroid nodules in diagnosing MTC during the COVID-19 pandemic.