Lipoadenoma: is it arising from thyroid or parathyroid? A diagnostic dilemma.

Fat-containing lesions of endocrine organs are rare. Distinguishing lipoadenomas of the thyroid gland from lipoadenomas of parathyroid glands can be challenging during intraoperative consultation. Our patient had a well-circumscribed tan-pink nodule present on the surface of the thyroid gland, exhibiting abundant fat interspersed between the cells, with ample eosinophilic cytoplasm arranged in trabeculae and solid sheets. Immunohistochemistry showed strong positivity for thyroglobulin confirming the origin of the nodule to be thyroid. Only few cases of lipoadenomas of the thyroid and parathyroid have been reported in the literature. There is considerable histologic overlap between the two, making it difficult to determine the site of origin. We briefly discuss the features that may be helpful in this distinction. Copyright 2002 S. Karger AG, Basel