Cardiac Metastasis From Anaplastic Thyroid Carcinoma

Background: Anaplastic thyroid carcinoma represents 2% of all thyroid carcinomas. The most common metastatic sites are lung and neck lymph nodes. Cardiac metastasis is extremely rare. Autopsy studies of patients with thyroid cancer have documented a frequency of metastatic cardiac involvement of 0%–2%. Clinical Case: A 57- year- old woman was admitted to the emergency room with a rapidly expanding neck mass of 3 months duration. She complained of pain in the anterior neck, dysphagia, dyspnea, palpitations and hemoptoic sputum. She further reported history of weight loss. She denied medical history of cancer in the family. Prior medical history was described as non- significant. On clinical examination, vital signs were normal. General swelling around the thyroid region was noted. A hard, tender, immobile mass was palpated. A superficial lymph node of about 5 cm in diameter was palpated in level II A and IIB. The patient was admitted to the hospital for further workup. Laboratory work up revealed, hemoglobin 7.6 g/dL, hematocrit 22.5%, white blood cells 15,000/mm(3), fasting plasma glucose 135 mg/dL and urea 59 mg/dL. Thyroid function tests revealed TSH 2.46 mUI/ml (normal range: 0.38-5.33 mUI/ ml), fT3 1.69 pg/ml (normal range: 2.39-6.79 pg/ml), fT4 0.57 ng/dl (normal range: 0.58-1.64 ng/dl). A fine needle aspiration cytology from the thyroid lesion described a poorly differentiated thyroid carcinoma. CT scan of the neck and chest revealed a large heterogeneous mass with hypointense areas involving the thyroid gland of 9 x 8 x 7 cm that surrounded the vertebral bodies and displaced and infiltrated the neck vessels, trachea and esophagus. In the right atrium and right ventricle three well- circumscribed ovoid masses were observed, the largest one measured approximately 21 x 17 mm, suggestive of cardiac metastases. Bilateral adrenal masses were also observed the largest one measuring 69 x 51 mm. Diagnosis of anaplastic thyroid cancer stage IVC was established with a large thyroid mass, widespread metastasis and poorly differentiated metastatic carcinoma on fine needle aspiration biopsy. During her hospitalization she presented both atrial tachycardia and atrial fibrillation and was started on amiodarone. A week later, the patient′s condition deteriorated and she died of respiratory arrest without having any further treatment for the tumor. Conclusion: In patients with established thyroid malignancy who develop cardiac arrhythmias, cardiac metastasis should be considered.