Severe Hypercalcemia Complicating a Giant Mediastinal Parathyroid Compressive Cyst- A Case Report

Introduction: Primary hyperparathyroidism (PHPT) is an endocrine condition caused by a single parathyroid adenoma (PTA) in 80-85%, multiple PTAs or PT gland hyperplasia in 15%; exceptionally a PT carcinoma (<1%). The final diagnosis includes hypercalcemia, raised or inappropriate PTH, and concordance between significant focal uptake at functional imaging and morphological features at US and/or MDCT assessment. According to literature data, a giant PTA is defined as weighing more than 350mg. Case report: A 62-year-old female patient presented with progressive hoarseness and expiratory dyspnea; nasofibroscopy revealed right vocal cord paralysis, FDG -PET ruled out any suspicious cervico- mediastinal mass uptake, F-choline PET-CT disclosed a 37 mmx 21mm x 30mm (12.2ml) cyst of the upper right mediastinum, MDCT showed focal tiny contrast enhancement of solid lower part that could be in favor of cystic PT adenoma. Two months later on, patient presented with sudden worsening of dyspnea, and severe hypercalcemia Surgical resection (combined head & neck and thoracic surgery) of the mass was successfully performed without complication. Conclusions: The diagnosis of a mediastinal functional cystic PTA is highly challenging because of the frequent negative result on parathyroid tracer scintigraphy. Surgical resection of the mass and postoperative histopathological diagnosis are necessary even if the clinical diagnosis of a PTA cannot be often obtained preoperatively. Decreases in the PTH and serum calcium level indicate successful resection of the functional PTA. Cystic FNA PTH wash -out under image- guidance could definitely make -up the full diagnosis pre operatively. Alternatives minimally invasive therapies will be discussed.