Ectopic lipoadenoma of parathyroid
A 58-year-old woman presented in Alzahra hospital of Isfahan in 2004 with huge multinodular goiter. Her thyroid function tests were within normal limit (euthyroid). The thyroid was such a sizable mass in the midline of neck and there was no remarkable point in patient’s past medical history and all of her laboratory data (including serum calcium) were normal. The patient underwent subtotal thyroidectomy because of very large size of thyroid. Inpatient’s chest X-ray was done before surgery, widening of mediastinum, especially right para tracheal was reported. The patient’s thoracic CT-scan showed a posterior mediastinal mass\nThe patient underwent subtotal thyroidectomy and excision of posterior mediastinal mass simultaneously. There was a large mass in the posterior mediastinum after partial sternotomy revealed that the mass was between vertebrae and superior vena cava and aorta, which was extracted completely. Therefore, subtotal thyroidectomy was done for the very large goiter.\nOn macroscopic examination, mediastinal mass was well circumscribed measuring 6*4*3 cm with rather soft consistency and a solid gray white cut surface with foci of hemorrhage and the thyroid was 54 g, measuring 7*5*4 cm and it was multilobular.\nOn microscopic examination, the thyroid was composed of thyroid follicles in varies sizes, some of them were huge follicles lined by flattened epithelium. Areas of fresh and old hemorrhage were seen within the goiter []. The mediastinal mass, microscopically, was composed of epithelial cells arranged in follicular and cellular nests pattern alter with abundant mature adipose tissue. Microscopic appearance of epithelial portion of the mass was closely resembled parathyroid tissue consisted of chief cells with granular acidophilic cytoplasm and clear cells with optically clear cytoplasm in a stroma with foci of myxoid change.\nImmunohistochemical study (Labeled Streptavidin-biotin-peroxidase method (LSAB), DakoCytomation) revealed negativity of thyroglobulin (Tg) and calcitonin, excluding the thyroid nature of the tumor. Also, vimentin (V) and NSE (Neuron Specific Enolase) were negative, thus excluding mesenchymal and neuroendocrine tumors of this area. Since, the tumor had microscopic criteria of lipoadenoma of parathyroid. This is a very rare presentation of parathyroid lipoadenoma in posterior mediastinum simultaneous with huge multinodular goiter. After surgery, the patient discharged with well condition and normal lab data.