"Ultrasonography is highly sensitive in determining the size and number of thyroid nodules. By itself, ultrasonography cannot reliably be used to distinguish a benign nodule from a malignant nodule. However, combining high-resolution sonography with Doppler and spectral analysis of the vascular characteristics of a thyroid nodule holds promise as a useful tool in screening thyroid nodules for malignancy. "
emedicine.com
Malignancy of the thyroid occurs in only 0.004% of the American population annually, representing approximately 12,000 new cases per year. Of all nodules, only 5% are found to be malignant.
The remainder of nodules discovered represent a variety of benign diagnoses, including
colloid nodules
thyroiditis
degenerative cysts
benign neoplasms
hyperplasia
If detected in the ED, a patient with an asymptomatic solitary thyroid nodule should first have thyroid function testing performed (i.e. TSH with reflex), then referral for an official ultrasound or nuclear scanning. Interestingly, most centers are referring fewer patients for nuclear scanning of nodules and instead referring to surgeons for fine needle aspiration biopsy (FNAB). The chief reason for this is that of thyroid nodules that undergo nuclear testing, 90% are found to be "cold" and only 10% of cold nodules are positive for malignancy. Cost effectiveness is greatly compromised.
FNAB has emerged as the most important step in the diagnostic evaluation of thyroid nodules. It is highly accurate, with mean sensitivity higher than 80% and mean specificity higher than 90%. FNAB is highly cost-effective compared with traditional workups that heavily depended on nuclear imaging and ultrasonography.
Nodules larger than 3 cm are thought to have an increased risk of malignancy. Risk of malignancy is lower in nodules with a predominantly perinodular pattern than in nodules with an exclusively central vascular pattern.
Case Resolution
Our patients TSH was found to be mildly elevated, but with a normal T4. She was referred back to her physician in Ohio.