Thyroid nodules

This week seems to be thyroid nodule week.

I did yet another ultrasound-guided fine-needle aspiration of the nodule today, assisted by my resident. And so we got into a relevant discussion about how to approach these.

The truth is, nodules are common; indeed in certain groups, thyroid nodules are found in the majority of people whether or not they know it.

The first question diagnostically to ask is if this might be a hyperfunctioning nodule- if the TSH is suppressed, this certainly opens up that possibility and in that case, radioiodine uptake and scan should be performed. And so the TSH should be one of the earlier diagnostic tests.

If however the TSH is normal and the nodule has large enough solid components, then FNA is probably indicated. Thyroid uptake/scan might not be too helpful as many thyroid cancers may not appear 'cold' while many 'cold' nodules might not be cancerous- so the decision to biopsy should depend more on sonographic features.

If one is dealing with multiple nodules, the conventional route was to biopsy the largest. These days though we'd often choose the sonographically most suspicious nodule, not necessarily the largest. Some suspicious features may include:

• Hypoechoic nodules
• Hypervascular on Doppler
• Presence of microcalcifications- may increase likelihood of papillary carcinoma
• Irregular or ill-defined borders

Typically, I do 4 passess with a 25G needle with an aspirator. Sometimes if it looks like a dry tap, I might pick a larger needle, but never a core needle. While some centers still do core biopsies, in my opinion this should not be done anymore; I'm obviously biased as I've seen some large hematomas with these, and I published a comparison study comparing core biopsies to FNAs. It's always best working with an experienced thyroid cytopathology group- fortunately we work with a good group of pathologists here.

Thankfully, all the biopsies this week came back benign. In these cases it's reasonable to repeat the US in 6-12 months to document stability; in the absence of growth I tend to back off on the surveillance intervals.

It was a good, relevant teaching topic for my fresh resident (only 2nd week into her 2nd year) as thyroid nodules are very common and so familiarity with this is necessary for a primary care physician.