Thyroidectomy: The treatment of choice
Thyroidectomy is the definitive therapy for MNG. A narrative review of 15 mostly retrospective cohort studies demonstrated MNG recurrence rates of 0% to 0.3% after total thyroidectomy, with follow-up intervals of 4.8 to 30 years.7
AACE consensus opinion recommends thyroidectomy for compressive symptoms, progressive growth, or when ultrasound or FNA results indicate thyroid cancer.2
A retrospective cohort study of 462 thyroidectomies for MNG found incidental thyroid carcinomas in 8.9% (41 patients). Risk factors included neck irradiation (odds ratio [OR]=21.64; 95% CI, 3.28-143), parenchymal calcifications on imaging (OR=2.30; 95% CI, 0.85-6.23), and family history of thyroid disease (OR=8.2; 95% CI, 2.15-29.87). Living in a goiter-endemic area was protective (OR=0.24; 95% CI, 0.07-0.83).8
Follow-up of patients with initial benign evaluation
Consensus opinion regarding follow-up of MNG is based on observational studies of the natural history of the condition. Benign MNG rarely progresses to malignancy. A review of 6 cohort studies, including 1265 patients with untreated nontoxic MNG who were followed for 60 to 130 months from 1990 to 2007, yielded an annual incidence range of 1.3 to 3.7 new cases of thyroid carcinoma per 1000 patients.9
Some goiters are more likely to enlarge. A retrospective cohort study of 488 patients treated surgically for MNG identified risk factors for enlargement: African American (OR=3.3; 95% CI, 2.0-5.4), age >40 years (OR=2.1; 95% CI, 1.2-3.8), and body mass index >30 (OR=2.5; 95% CI, 1.5-4.0).10
RECOMMENDATIONS
The AACE and the ATA recommend that patients with MNG with benign nodules have a repeat examination, TSH, and ultrasound in 6 to 18 months. Follow-up of stable nodules can then be done in 3 to 5 years.
An enlarging nodule requires repeat FNA.2 If palpation or ultrasound reveal evidence of nodule growth (more than a 50% change in volume or a 20% increase in at least 2 nodule dimensions, with a minimal increase of 2 mm in solid nodules or the solid portion of mixed cystic-solid nodules), the AACE and ATA recommend FNA, preferably with ultrasound guidance.3 Low TSH suggests autonomous nodules and the ATA recommends radionuclide scanning with FNA of hypofunctioning nodules with suspicious US features.3