The isthmus is a bridge of tissues that connects the two lobes of the thyroid gland, located on either side of the windpipe at the front of the neck. Just 2%–9% of thyroid cancers are found in the isthmus, but cancers in this area are more likely to spread outside of the thyroid than cancers found in other parts of the thyroid. 1Which is more at risk for cancer the isthmus or the lobar?
Cancer risk can differ based on whether nodules are found in the isthmus or lobar areas of the thyroid. Recent research found that nodules in the thyroid isthmus pose a greater risk of malignancy compared with nodules in the lobes. Nodules in the lower portion of the lobes are believed to be at least risk for cancer. 4 What kind of biopsy is done on the thyroid?
Thyroid fine needle aspiration biopsy (FNAB): a simple procedure that is done in the doctor’s office to determine if a thyroid nodule is benign (non-cancerous) or cancer. The doctor uses a very thin needle to withdraw cells from the thyroid nodule.Are there any cancers in the thyroid isthmus?
Hahn SY et al. Ultrasound findings of papillary thyroid carcinoma originating in the isthmus: comparison with lobe originating papillary thyroid carcinoma. AJR Am J Roentgenol 2014;203:637-42.