SUN-606 Thyroid Cancer Presenting As Acute Limb Ischemia

Abstract

Abstract INTRODUCTION: Cardiac metastases are present in up to 20% of patients with extra-cardiac malignancies and are 40 times more common than primary cardiac tumors. However, thyroid\xa0cancer metastatic\xa0to the\xa0heart\xa0is rare. We report a case of mixed follicular and papillary thyroid carcinoma with the presence of anaplastic features presenting with cardiac metastasis. CASE: A 52-year old\xa0female\xa0non-smoker was admitted with right arm ischemia. Two years earlier, she had been diagnosed with thyroid cancer and underwent total thyroidectomy. Surgical pathology at the time revealed multifocal follicular and papillary thyroid cancer with focal anaplastic changes and positive central lymph nodes. She was treated with 150mCi RAI for remnant ablation, with the post treatment whole-body scan revealing radiotracer activity in the neck but no scintigraphic evidence of distant metastases. She was subsequently lost to follow-up. At the time of admission, she was found to have acute limb ischemia due to axillary artery thrombosis and underwent fasciotomy and embolectomy. Chest CT revealed multiple cavitary lung lesions and a left ventricular mass with adherent thrombus. Biopsy of the lung lesions confirmed metastatic poorly differentiated thyroid cancer (immunohistochemical staining positive for Pax8, TTF-1 and P40, but negative for thyroglobulin). PET scan showed multiple hypermetabolic lesions, including bilateral pulmonary nodules, right hilar adenopathy, a left ventricular mass, and right hepatic lobe lesion. Mutational analysis showed BRAF V600E mutation. The patient is receiving salvage chemotherapy with dabrafenib/ trametinib. DISCUSSION: While rare, follicular carcinoma is the most common thyroid cancer with cardiac metastasis, mostly involving the central veins and right atrium. Papillary thyroid cancer tends to metastasize through the lymphatic system and involve the right side of the heart. The aggressive behavior of our patient’s tumor, with involvement of the left heart suggestive of vascular metastasis, is likely due to the concurrent presence of anaplastic de-differentiation. Anaplastic carcinomas are highly aggressive neoplasms and 71% are said to occur simultaneously with a well-differentiated thyroid cancer. About 50% of patients diagnosed with anaplastic thyroid cancer have metastatic disease at the time of diagnosis and another 25% develop metastasis during the course of disease. The prognosis is very poor with median survival ranging from 4-12 months.