Thyroid Nodules

Thyroid nodules are relatively uncommon in children. Pediatric thyroid carcinoma comprises 0.5% to 3% of pediatric malignancies. Only 10% of thyroid carcinomas occur in patients younger than 21 years of age, and the majority of those occur between 15 and 19 years of age. The risk of malignancy in a thyroid nodule is greater in a child than in an adult. Fortunately, survival rates exceed 90% in most children. Although the majority of solitary thyroid nodules are benign, malignancy is identified in 10% to 24%. Benign cysts, adenomas, and colloid nodules are the most common benign thyroid masses. The most common carcinomas identified in solitary thyroid nodules are papillary (70% to 80%), follicular (15% to 20%), medullary (3% to 10%), and anaplastic (3%).

Most thyroid nodules present as painless masses near the midline of the lower neck. The time of onset; rate of growth; and presence of pain, hoarseness, and dysphagia as well as systemic symptoms of hypo- and hyperthyroidism are important to identify. Prior radiation exposure significantly increases the likelihood of malignancy. There may be an increased risk of malignancy in certain illnesses, such as iodine deficiency, Hashimoto thyroiditis, and Grave disease. Familial syndromes such as Pendred or Gardner syndromes as well as multiple endocrine neoplasia (MEN) 2A and 2B clearly increase the risk of thyroid carcinoma. (see link: MEN/MEA type I,II,III)  Prophylactic thyroidectomy is recommended for children who have high-risk syndromes.

Physical examination should include assessment for vocal cord mobility and cervical lymphadenopathy as well as for size and characteristics of the thyroid nodule.

Although measurements of thyroid functions, including thyroid-stimulating hormone levels and thyroxin levels, should be obtained, these are rarely abnormal in asymptomatic individuals and do not differentiate benign from malignant lesions. Chest radiography and lateral neck films usually appear normal, but may show radiopaque psammoma bodies  in papillary carcinomas. Thyroid gland scintigraphy (thyroid scan) usually is performed with technetium 99 or iodine  123. The degree of isotope concentration differentiates a cold nodule from a hot nodule. Approximately 40% to 70% of thyroid nodules in children are cold, with 17% to 36% of those being malignant. Hot nodules comprise 5% of thyroid nodules, and most are toxic but rarely malignant.

Ultrasonography can be useful for differentiating a solid from a cystic mass and for evaluating for multiple nodules such as a multinodular goiter. Cystic lesions, however, may be malignant.

Fine-needle aspiration (FNA) biopsy is considered by most authors to be the diagnostic procedure of choice for assessing solitary thyroid nodules. Based on results of FNA, an experienced cytopathologist can segregate nodules accurately into negative, nondiagnostic, or probable malignant categories. The overall diagnostic accuracy of FNA cytology is approximately 90%. Because of this high diagnostic accuracy, thyroid scans and ultrasonography are usually not necessary.

Total thyroidectomy is not recommended unless high-risk malignancy is diagnosed definitively. Hemithyroidectomy occasionally is recommended for biopsy if FNA cytology results are equivocal and usually is recommended for definitive diagnosis of positive FNA cytology.

Summary

Benign

• 1. Clinical features:

  • - multiple nodules and/or diffuse goiter

  • - soft, well-circumscribed nodule

  • - acute pain

• 2. Treatment:

  • - observation for spontaneous remission

  • - may need levo-thyroxine for Hasimoto thyroiditis

  • - cystic lesions may require aspiration

B. Malignant

• 1. Clinical features:

  • - prior history of neck irradiation

  • - single, firm, irregular, painless or only slightly tender nodule

  • - persistent growth of a nodule over a few months

  • - enlarged cervical nodes

• 2. Types

• - papillary cancer

• - follicular cancer

• - medullary thyroid cancer, which may be part of the multiple endocrine neoplasia syndromes:

• MEN 2a: medullary carcinoma, pheochromocytoma, and hyperparathyroidism
• MEN 2b: medullary carcinoma, pheochromocytoma, along with a Marfanoid body habitus, mucosal neuromas of the eyelids and tongue, and gastrointestinal ganglioneuromatosis

Treatment:

• surgical intervention

• post-operative ablation with radioactive iodine

• close follow-up for recurrence

CHLA Board Review

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