SUN-598 Neck Pain as an Initial Presentation of Medullary Thyroid Cancer

Background: Neck pain is common in adults and can be caused by various conditions, most commonly due to musculoskeletal disorder. Thyroid cancer is not usually considered as an etiology for neck pain. We report a patient with an initial presentation of neck pain due to medullary thyroid cancer (MTC). Case Presentation: A 40-year-old female without significant medical history initially presented to her primary care provider with 12 months of left-sided neck pain, point tenderness in the lower neck, and minimal improvement in pain despite multiple courses of physical therapy for presumed musculoskeletal pathology. She noted recent hoarseness, but no esophageal, respiratory, or endocrine symptoms. On physical examination, a discrete left-sided thyroid nodule was palpated. Thyroid ultrasound confirmed a 1.0 x 1.0 x 1.5 cm solid, hypoechoic, taller than wide nodule with irregular borders in the left thyroid lobe. Thyroid function tests including TSH and free T4 were normal. Fine needle aspiration (FNA) of the nodule showed numerous malignant appearing cells with background amyloid suggestive of MTC. Serum calcitonin and CEA were found to be elevated to 206 pg/mL and 8.5 ng/mL, respectively (reference ranges 0-5 pg/mL and 0.2-4.7 ng/mL). Calcium stimulation testing was performed with elevation of calcitonin to 413 pg/mL. Further evaluation disclosed left-sided vocal fold paresis. She was scheduled for total thyroidectomy with central and left lateral neck lymph node dissections and referred for genetic testing. Discussion: Neck pain is an uncommon presentation of thyroid cancer with a reported prevalence of 22% in patients with MTC, 6% with papillary thyroid cancer (1), and 26% in anaplastic thyroid cancer (2). Diagnosis of MTC is usually made by FNA and confirmed with elevated serum calcitonin. In indeterminate cases, calcium stimulation testing can be a useful adjunct to confirm MTC. Given its association with familial tumor syndromes, genetic testing is recommended in all new MTC cases to identify at risk families for early intervention, potentially to include prophylactic thyroidectomy. MTC patients also require serial calcitonin monitoring after surgery to identify recurrences and residual disease. It is important to examine the neck and thyroid gland carefully in patients with neck pain. References: Guerrero MA, et al. Medullary Thyroid Cancer: It is a pain in the neck? Journal of Caner. 20112:200-205. Taccaliti A, Silvetti F, Palmonella G, Boscaro M. Anap