A thyroid nodule is a nodule that grows in the thyroid gland in front of the larynx. What is meant by a diffuse thyroid nodule is mainly an ultrasound finding of multiple nodules of varying sizes and relatively similar diameters in the thyroid gland bilaterally, which is called a diffuse thyroid nodule. Diffuse thyroid nodules are commonly associated with diseases, mainly chronic lymphocytic goiter, which can be called Hashimoto’s disease. Once a diffuse thyroid nodule is present, it is best to have a thyroid function test in addition to an ultrasound. In the absence of these symptoms, however, treatment can be conservative, with ultrasound to regularly monitor changes in the thyroid gland and, if necessary, a puncture biopsy to clarify the nature.