Concurrent Papillary and Follicular Thyroid Cancer Presenting as Shoulder Pain

Differentiated thyroid cancer arises from thyroid follicular epithelial cells. It accounts for more than 90% of thyroid cancers. In areas of sufficient iodine nutrition, about 85% of differentiated thyroid cancers are papillary, 10% are follicular and 3% are Hurthle cell carcinomas. The coexistence of different types of thyroid cancer in a single patient is a rare condition. This is the case of a 56 year-old man with medical history of arterial hypertension who presented to clinics with right shoulder pain. Imaging of the right shoulder showed a osteolytic lesion involving the right humerus with associated cortical disruption consistent with pathological fracture secondary to metastatic disease. Bone biopsy showed papillary thyroid carcinoma. Subsequently, ultrasound-guided fine needle aspiration biopsy to a right lobe nodule was performed, which confirmed the presence of papillary thyroid carcinoma. There was also evidence of cervical lymph node involvement. Patient proceeded to total thyroidectomy with neck dissection, and surgical pathology revealed the presence of 2.5 cm right lobe papillary carcinoma and 1.5 cm left lobe follicular carcinoma. Postoperatively, he was found with persistent elevated thyroid-stimulating hormone (TSH) and elevated quantitative thyroglobulin with elevated thyroglobulin antibodies. Patient received therapeutic radioiodine (I-131) for ablation of thyroid cancer. Whole body iodine scan demonstrated residual functioning thyroid tissue within post-thyroidectomy bed, with or without residual carcinoma, and large expansile uptake lesion involving the right humeral head and neck. Therefore, patient will receive a second dose of radioactive iodine. He has been started on thyroid hormone replacement with a goal of TSH <0.1 uIU/mL for high risk American Thyroid Association (ATA) stratification, and has remained clinically euthyroid. Thyroid carcinoma is the most common endocrine malignancy and one of the most rapidly increasing cancers in the United States. This increase in incidence is largely due to incidental detection on diagnostic imaging. Here we present an uncommon case of two distinct thyroid malignancies occurring simultaneously in a patient presenting with a pathological fracture. Synchronous occurrence of two types of differentiated thyroid cancer is a rare event, and has only been reported in case series. Bone metastasis from differentiated thyroid cancer can occur in 2-13% of patients. Despite the therapy for papillary thyroid carcinoma and follicular thyroid carcinoma remain the same, proper identification will lead to prompt therapy and increased survival. Physicians should be aware of this variety.