This disorder results from transplacental passage of maternal TSIs and may be masked for several days until the short-lived effects of transplacental maternal antithyroid medication wear off (assuming the mother was receiving such medication), at which time the effects of TSIs are observed. Irritability, tachycardia (often with signs of cardiac failure simulating cardiomyopathy), polycythemia, craniosynostosis, bone age advancement, poor feeding, and failure to thrive are the clinical hallmarks. This condition may be anticipated if the mother is known to be thyrotoxic in pregnancy. Cure of hyperthyroidism before pregnancy (surgery or radioiodine treatment) limits or curtails T4 production but not the underlying immune disturbance producing TSIs; thus the infant still may be affected, at least transiently.
Treatment for a severely affected neonate includes methimazole and, as needed, a beta blocker to help decrease symptoms. Because the half-life of the immunoglobulin is several weeks, spontaneous resolution of neonatal thyrotoxicosis resulting from transplacental passage of TSIs usually occurs by 2 to 3 months of age. Observation without treatment is indicated in patients who are minimally affected.
About 2% of children develop solitary thyroid nodules, most of which are benign. Evaluation of a nodule includes thyroid function tests, neck ultrasound, and, if needed, fine-needle aspiration (FNA). Ultrasound guidance may be needed for aspiration of small nodules or those not palpable. Nodules found to be benign on FNA may be monitored through clinical exam and ultrasound.
Carcinoma of the thyroid is rare in children (1% of all pediatric cancers in the 5to 9-year-old age group and up to 7% of cancers in the 15to 19-year-old age group). Papillary and follicular carcinomas represent 90% of childhood thyroid cancers. A history of therapeutic head or neck irradiation or radiation exposure from nuclear accidents predisposes a child to thyroid cancer. Carcinoma usually presents as a firm to hard, painless nonfunctional solitary nodule and may spread to adjacent lymph nodes. Rapid growth, hoarseness (recurrent laryngeal nerve involvement), and lung metastasis may be present. If the nodule is solid on ultrasound, is cold on radioiodine scanning, and feels hard, the likelihood of a carcinoma is high. Excisional biopsy usually is performed, but FNA biopsy also may be diagnostic.
Treatment includes total thyroidectomy, selective regional node dissection, and radioablation with 131I for residual or recurrent disease. The prognosis is usually good if the disease is diagnosed early.
Medullary carcinoma of the thyroid may be asymptomatic except for a mass. Diagnosis is based on the presenceof elevated calcitonin levels, either in the basal state or after pentagastrin stimulation (difficult to obtain) and histologicexamination. This tumor most often occurs with multipleendocrine neoplasia 2a or 2b (MEN), possibly in a familial pattern. In some families, the presence of mutations ofthe RET proto-oncogene is predictive of the development of medullary carcinoma of the thyroid. The location of the mutation can help determine when removal of the thyroid iswarranted. Genetic screening of other members of the family is indicated after a proband is recognized. Prophylacticthyroidectomy is indicated for the family members with thesame allele.