Thyroid adenoma (thyroid adenoma) is the most common benign tumor of the thyroid gland. It can be morphologically classified as follicular. and papillary cystic adenomas. Follicular adenoma is more common and surrounded by an intact envelope, while papillary cystic adenoma is rare and often not easily distinguished from papillary adenocarcinoma and should be noted at the time of diagnosis. The disease is most commonly seen in women under 40 years of age. Clinical presentation Round or oval nodules appear on the neck, mostly solitary. It is slightly hard, smooth surface, no pressure pain, and moves up and down with swallowing. Most patients have no symptoms. Adenoma growth is slow? s growth is slow. When a papillary cystic adenoma has intracapsular hemorrhage due to rupture of blood vessels in the cyst wall, the tumor may increase rapidly in size within a short period of time, resulting in localized distension and pain. Thyroid adenomas are clinically difficult to distinguish from the solitary nodules of nodular goiter. Histologically, adenomas have an intact envelope with normal surrounding tissue and are clearly demarcated, whereas the envelope of a solitary nodule in a nodular goiter is often incomplete. Because thyroid adenomas have the potential to cause hyperthyroidism (about 20% incidence) and malignancy (about 10% incidence), early excision of a large portion of the affected thyroid gland, including the adenoma, or part of it (small adenoma), is indicated. The excised specimen must be immediately examined by frozen section to determine whether there is malignancy.