Thyroid neoplasms containing mature fat: a report of two cases and review of the literature.

Thyrolipoma or adenolipoma of the thyroid, defined as a thyroid adenoma containing mature fat tissue, is rare and has been reported only seven times. Moreover, the presence of mature fat tissue has been described in only one case of thyroid carcinoma (papillary subtype). We describe one case of thyrolipoma and one case of fat containing follicular carcinoma of the thyroid, and we reviewed the literature on the presence of adipose tissue in the thyroid. It was found that aside from the above conditions, mature adipose tissue has been reported in diffuse lipomatosis of the thyroid, some amyloid goiters, a colloid goiter, and even some normal thyroids. Aside from the presence of mature fat tissue, the clinicopathologic features of fat containing thyroid tumors are not different from those of their usual counterparts.