Thyroid Cancer

Posted by Graham McMahon • December 17th, 2010

In the latest Case Record of the Massachusetts General Hospital,  a 13-year-old girl was seen in the pediatric endocrinology clinic because of an enlarging neck mass. The thyroid gland was diffusely enlarged; levels of thyrotropin and antithyroglobulin antibodies were elevated. Ultrasonography revealed diffusely abnormal parenchyma with calcifications.

Approximately 5% of thyroid nodules in adults are malignant, whereas approximately 20% of thyroid nodules in pediatric patients are cancers (reported range, 2 to 40%).

Clinical Pearls

What is the most common cause of thyroid cancer in children?

Papillary thyroid cancers are the most common type of thyroid cancer in children, followed by follicular and medullary thyroid cancers. Anaplastic cancers, primary thyroid lymphomas, and metastatic cancer are typically seen in older adults and rarely in children.

What are the operative risks during thyroidectomy?

Permanent injury to one recurrent laryngeal nerve occurs in 1 to 2% of patients who undergo thyroid surgery with an experienced surgeon but can occur in up to 7% of patients whose surgeons are inexperienced. Bilateral nerve injury is very rare. Permanent hypoparathyroidism, which occurs when none of the four parathyroid glands retain function after thyroid surgery, is seen in 2% of patients; temporary hypoparathyroidism occurs in up to 20% of patients.

Table 1. Differential Diagnosis of Goiter in an Adolescent with Mild Hypothyroidism or Euthyroidism.

Morning Report Questions

Q: How should levothyroxine therapy be managed following thyroidectomy for a thyroid cancer?

A: Slightly supraphysiologic doses of thyroid hormone are administered to suppress serum thyrotropin levels, since thyrotropin is a growth factor for persistent disease. The suppression of thyrotropin levels is associated with better outcomes in young patients.

Q: What is the most sensitive imaging modality to detect recurrence of thyroid cancer?

A: Ultrasonography is the most sensitive imaging technique for detecting the recurrence of thyroid cancer in the anterior neck; it is also the primary imaging technique for long-term follow-up.

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