Endocrine Abstracts

Introduction: The parathyroid gland is made up of principal cells and oxyphilic cells, surrounded by stroma, whose main component is adipose tissue, which accounts for 25% of the content of the parathyroid in adults. In parathyroid adenomas, prominent parathyroid cellularity can be observed, with a very marked decrease in the stroma. Parathyroid lipoadenoma is a rare variant of parathyroid adenoma, characterized by hyperfunctioning parathyroid cells in an abundant fatty stroma.

Case reports.: We present a case of a 76-year-old woman with a history of high blood pressure and a previous diagnosis of non-toxic multinodular goiter without follow-up. During an outpatient study due to weakness and incipient cognitive disorders, severe hypercalcemia of 18.3 mg/dl with creatinine of 2.3 mg/dl was detected, for which she was admitted for treatment and study. In previous tests, a progressive increase in calcium was observed that had not been studied, with at least 6 years of evolution, with levels of 15 mg/dl the previous year. During admission, she showed parathyroid hormone (PTH) figures of 2,310.7 pg/ml (NV: 15–68), 25-OH-vitamin D of 12 ng/ml and TSH 0.12 IU/ml, with normal FT4. Cervical ultrasound revealed a multinodular goiter. In the 99mTc-sestamibi SPECT scintigraphy with a heterogeneous uptake of the radiotracer. Cervicothoracic CT revealed a right paratracheal mass with well-defined borders, with solid and fat densities, and dimensions of 5 × 5 × 8 cm, with no other lesions. A biopsy of the mass was performed, obtaining a whitish-brown sample consisting of adipose tissue and tissue with benign characteristics, with a low proliferative index (Ki67 of 1%), confirming its parathyroid origin with immunohistochemical techniques (positivity for the expression of panCK, PAX8 and chromogranin, and negative for PLAP, TTF1 and thyroglobulin). All this compatible with parathyroid lipoadenoma. Before surgical treatment, we started treatment with cinacalcet 30 mg/day, zoledronic acid and fluid therapy. The patient underwent total thyroidectomy and resection of the mediastinal mass. Intraoperative PTH was determined with progressive reduction (basal: 609.8 pg/ml; 5’: 240 pg/ml; 10’: 155.6 pg/ml; 20’: 132.6 pg/ml). The mediastinal surgical specimen, 91 g and 9 × 5 × 3.5 cm, had a nodular appearance with a smooth, yellowish surface, covered by a fibrous capsule. The definitive histological study confirmed nodular thyroid hyperplasia and mediastinal parathyroid lipoadenoma. At hospital discharge, the patient presented calcium 9.34 mg/dl and was undergoing outpatient treatment with LT4 and calcium and vitamin D supplements