A Tale of Three Cases When Thyroid Cancer Does Not Exist but Metastases Do. A Three-Case Series of Metastatic Follicular Thyroid Carcinoma

Background: Follicular and papillary thyroid carcinomas represent the majority of all malignancies of the thyroid gland. However, follicular thyroid carcinoma (FTC) is much more difficult to diagnose and manage than its papillary counterpart. Among other factors this could be explained by changing diagnostic criteria and by FTC potential for remote distant and often unpredictable metastases sites. Clinical Cases: In our high volume major academic referral center we have encountered three intriguing cases of metastatic FTC with negative surgical thyroid pathology. The first patient is a 61-year-old woman, who at age 50 was diagnosed with 5.4x3.5x4.2 cm left thyroid nodule (TN). FNAB reported hyperplastic nodule versus follicular neoplasm, subsequent surgical pathology report after lobectomy showed hyperplastic nodule. At age 58 she developed a pathological fracture of the 5(th) thoracic vertebra and pathology report indicated follicular carcinoma of thyroid origin. TG level at this time was 577 ng/ml. Pathology report from completion thyroidectomy again showed nodular hyperplasia, but reexamination of previously resected lobe demonstrated minimally invasive FTC. The second patient is an 83-year-old woman who at age 68 underwent lobectomy for left sided-goiter, pathology report showed benign follicular adenoma. At age 77 she was found to have right-sided skull mass which was determined to be a follicular carcinoma of thyroid origin. Pathology report from completion thyroidectomy was consistent with nodular hyperplasia. At age 82 the patient was noticed to have increased RAI uptake in thyroid bed, sternum, kidneys, and gastroesophageal junction. TG level at this time was 2214 ng/ml. The third patient is a 56-year-old woman initially diagnosed with a 3.5x2.8x2.2cm right TN at age 53. Lobectomy, performed for diagnostic and therapeutic purposes, showed benign follicular adenoma. At age 56 she developed a pathological fracture of the 3(rd) thoracic vertebra, follicular carcinoma of thyroid origin was shown on pathology report. TG level at this time was 1694 ng/ml. The patient underwent completion thyroidectomy demonstrating multinodular hyperplasia. Conclusion: This case series emphasizes on the pitfalls of follicular neoplasms diagnosis and management. We suggest prolonged clinical and biochemical surveillance of the patients with what appears to be follicular adenoma after lobectomy. Following serum thyroglobulin perhaps represents the most cost-effective surveillance approach of those patients.