SUN-616 A Rapidly Enlarging Neck Mass in a 59-Year-Old Woman

Background: Anaplastic thyroid cancers (ATC) are extremely aggressive and rapidly fatal. We report a case of ATC presenting as a rapidly enlarging, painful neck mass. Case Presentation: A 59 year old female presented with 2 month history of a right-sided, painful neck mass and inability to project her voice. Review of systems was positive for dyspnea when supine, intermittent headaches, and difficulty swallowing. Exam revealed a palpable 3.0 cm hard, tender thyroid mass. Cranial nerves were grossly intact. Initial laboratory results showed TSH 1.1 mcIU/mL, calcitonin <2.0 pg/mL. Fine needle aspiration of thyroid mass revealed large cells with abundant eosinophilic cytoplasm, nuclear pleomorphism, and abundant necrosis. Thyroid u/s revealed a 3.5 cm irregular right thyroid mass with cystic areas, abutting the trachea and multiple nodules with irregular margins in the left thyroid lobe. Neck CT described a 3.8 cm mass with variegated enhancement abutting the trachea without luminal invasion. Brain MRI noted a 2.1 cm dural mass over the left occipital lobe with histology confirming metastatic ATC. Discussion Patient’s thyroid biopsy revealed de-differentiated (anaplastic) thyroid cancer given the abundant necrosis and negative TTF-1 mRNA. Distant metastatic disease was found on PET scan to include brain and lungs. This is a rare (1-2 cases per million), aggressive and often lethal malignancy (1). The mean age at diagnosis is 65 years with 60-70% of tumors occurring in women. Mean survival time is usually less than 6 months with 90% presenting with metastatic disease (2). An enlarging hard and often tender neck mass and cervical lymphadenopathy are typical at presentation. On cytopathology, morphologic patterns include spindle cell, pleomorphic giant cell +/- squamoid with extensive necrosis is typical as seen in our patient. There is no effective therapy for metastatic anaplastic thyroid cancer with few randomized control trials evaluating different strategies. Our patient underwent total thyroidectomy with tracheostomy tube placement to protect her airway. Resection of the dural-based mass revealed metastatic ATC. In addition to surgery, chemotherapy and radiation have been used as well as mutation directed (BRAF and p53 are common in anaplastic) therapy but studies have been small and only showing a 29% response rate (3). Radiation and chemotherapy were planned but ultimately, the patient chose to forgo further therapy and return to her native country of Kenya. References: 1) Akslen LA, et al. Incidence of thyroid cancer in Norway 1970-1985. Population review on time trend, sex, age, histological type and tumour stage in 2625 cases. APMIS.1990;98:549. 2) Nagaiah G, et al. Anaplastic Thyroid Cancer: a review of epidemiology, pathogenesis, and treatment. J Oncol 2011; 2011: 542358. 3) Hyman DM, et al. Vemurafenib in Multiple Nonmelanoma Cancers with BRAF V600 Mutations. NEJM. 2015;373:726.