My daughter has a 1.1cm hypoechoic density on the lt. thyroid gland inferior to the parathyroid gland (hx: hoshimoto's) should we be concerned?

Would biopsy: I would generally biopsy any lump on the thyroid gland 1cm or larger. Hashimoto's does make the results of the biopsy a little more confusing sometimes, but that wouldn't keep me from doing an ultrasound guided needle biopsy. Talk to a surgeon who regularly performs thyroid surgery.

Depends: Depends on what it looks like on the ultrasound, does it have irregular border, does it has calcium inside it, does it has blood flow inside it? Generally, nodule over 1 cm can be biopsy using the ultrasound but not all nodules > 1 cm needs to be biopsied. The decision to purdue it is between the comfort level of you and your physician. At the very least, get another u/s in 1 year.