Fat-containing lesions of the thyroid gland.

Thyroid lesions containing adipose tissue are rare; only scattered case reports are recorded. This study of 17 lipomatous thyroid lesions on file at the Armed Forces Institute of Pathology was undertaken to better document the full range of these abnormalities. Patient ages ranged from 11 to 75 years; nine patients were female and eight were male. Fat-containing thyroid neoplasms included seven papillary carcinomas, four adenomatoid nodules, one follicular adenoma, and one minimally invasive follicular carcinoma. Nonneoplastic conditions associated with adipose tissue included four cases of amyloid goiter, two cases of lymphocytic thyroiditis, one case of dyshormonogenetic goiter, and one case of thyroid atrophy. This study documents the presence of adipose tissue in a wider range of benign and malignant thyroid lesions than has previously been reported.