Hurthle Cell Carcinoma with Bone Metastasis

Hurthle cell thyroid cancer is usually classified as a type of Follicular thyroid cancer. It comprises about 3-5% of thyroid cancer cases. Hurthle cell thyroid cancers are known for their more aggressive tumor biology; metastases are observed in a minority of cases, and long-term survival can be expected.

Case Description:

A 43-year-old Caucasian male underwent total thyroidectomy for a 4.8 cm left-sided thyroid nodule with a 10-40% risk of malignancy on FNA and was subsequently diagnosed with follicular thyroid cancer with Hurthle cell features. The initial pathology report revealed left lobe follicular carcinoma with Hurthle cell features. Tumor size was 5.9 cm with margins uninvolved and encapsulated angioinvasion. Lymphatic invasion and extrathyroidal extension were not identified. Right lobe pathology revealed noninvasive follicular thyroid neoplasm with papillary-like nuclear features. The size of the tumor was 0.4 cm with margins uninvolved. Lymphatic invasion and extrathyroidal extension were not identified.

Following thyroidectomy, one course of 101 MCI of radioactive iodine therapy was administered and a subsequent whole-body scan showed post-ablative intense radiotracer uptake within the thyroid bed. Thirteen months following surgery, thyroglobulin levels began increasing. PET/CT showed hypermetabolic right sixth rib, L4, sacral, and right pubic lesions. A biopsy of the right sixth rib with pathology yielded results consistent with thyroid cancer. The decision was made to start the patient on Lenvatinib for RAI refractory disease.

Discussion:

Only limited information exists on the pathologic aspects of thyroid carcinomas with bone metastases; most large studies have concentrated mainly on their clinical features.

Radioactive iodine ablation is the first-line treatment in patients with metastatic thyroid cancer. However, we rarely see radioiodine refractory (RAIR) thyroid cancer.

Radioiodine-refractory thyroid cancers lose the ability to efficiently concentrate iodine. The tyrosine kinase inhibitors are standard treatments for patients with radioiodine-refractory thyroid cancer.

Lenvatinib, as compared with placebo, is associated with significant improvements in progression-free survival and the response rate among patients with iodine-131–refractory thyroid cancer.