Benign tumors of heterotopic tissue in the thyroid gland: a report of two cases of lipomatous lesions.

A report of two cases, concerning heterotopic nests of fat cells in the thyroid gland, is presented here together with a review of lipomatous lesions in the literature. Both cases involved patients who presented with goiter; one had Grave's disease and the other had adenomatous hyperplasia. The fat cells were principally located in the subcapsular areas and scattered among the follicles. The distribution of the immunohistochemical staining, and the morphologic characteristics of the adipose tissue, suggested a probable origin of the fat cells from inclusion nests during embryogenesis of the thyroid gland.