It has am increased incidence in iodine-rich areas and in those who have received neck irradiation and typically spreads to the lymph nodes.
The tumours are often described as minimal (< equiv="Content-Type" content="text/html; charset=utf-8">psammoma bodies:
These are calcifications with an unusual (and pretty) lamellar pattern. You can see psammoma bodies in any carcinoma with a papillary pattern (so just because you see them, that doesn’t mean you’re necessarily dealing with a papillary thyroid carcinoma). But if you are looking at a thyroid carcinoma and trying to figure out which kind it is (papillary, follicular, medullary or anaplastic thyroid carcinoma), seeing psammoma bodies would be very helpful. Since psammoma bodies are not seen in any other type of thyroid carcinoma, you would immediately think of papillary thyroid carcinoma.