Ectopic lipoadenoma of parathyroid.

A parathyroid lipoadenoma is a very rare cause of mediastinal mass. The clinical features of this pathologic entity is similar to those of the more common pathologic variants of parathyroid disease associated with primary hyperparathyroidism. A 58-year-old woman presented with huge multinodular goiter. Her thoracic CT scan was done before surgery, showed a posterior mediastinal mass. On microscopic examination, the thyroid was composed of thyroid follicles in varies sizes, compatible with a multinodular goiter and the mediastinal mass, microscopically, was composed of epithelial cells arranged in follicular and cellular nests pattern alter with abundant mature adipose tissue, morphologically closely resembled parathyroid tissue. Thyroid, mesenchymal and neuroendocrine origin for this tumor excluded by immunohistochemistry and the mass was diagnosed as a parathyroid lipoadenoma. In our case, there is a non functional parathyroid lipoadenoma with a very rare presence.