Parathyroid carcinoma and oxyphil parathyroid adenoma: an uncommon case of misinterpretation in clinical practice.

A 46 year-old male presented with persistently high level of serum parathyroid hormone (PTH), despite successful resection of an oxyphilic cell parathyroid adenoma of the left lower gland. Renal function and serum calcium were normal, leading to vitamin D deficiency being considered. Tc99m-sestamibi parathyroid scintigraphy showed no capitation, but a cervical ultrasound demonstrated an increase in the lower parathyroids. Surgery confirmed that the right gland was normal but the left corresponded to parathyroid carcinoma. The patient developed severe hypocalcemia, with PTH values being consistent with hypoparathyroidism for a few months. However, a progressive increase in calcium and PTH serum levels indicated recurrence of disease. Tc99m-sestamibi scintigraphy demonstrated hyperfixation in topography of the left inferior parathyroid and the patient was subjected to a third and more extensive surgery, with removal of lymph nodes and adjacent thyroid tissue. Serum calcium and PTH remained elevated, requiring loop diuretics and intravenous bisphosphonates to control hypercalcemia. Cervical radiotherapy was implemented as adjuvant therapy. After two months the patient complained of dyspnea, and a CT scan of the chest demonstrated areas of parenchymal condensation, suggestive of actinic pneumonitis. At the 2-year follow-up no major issues were evident.