Endocrine Abstracts

Primary hyperparathyroidism (PHPT) is rarely caused by parathyroid adenoma with cystic degeneration, especially by the cyst localized in mediastinum. Both differential diagnosis of mediastinal cyst and management of the patient can be challenging.

Case presentation: A 57 years old woman was transferred from district hospital where her urosepsis and nephrolithiasis had been treated successfully. A liquid collection in left hemithorax had also been found during radiological examination. She underwent thoracocentesis under CT because empyema had been suspected as a source of sepsis. Neither pus nor malignancy was found at cytological examination. Her serum parathormon (PTH) was high–14, later 78 pmol/l (normal range 1–7) together with serum calcium 2.62 mmol/l (2.15–2.55), ionized calcium 1.99 mmol/l (0.9–1.3), phosphate 0.61 mmol/l (0.84–1.45), and albumin 25.9 g/l (34–48). The situation suddenly became complicated with pancreatitis, symptoms from compression by large cyst and recurrent fever. Her calcium levels were only transiently stabilized after treatment with Cinacalcet (Mimpara) and calcitonin. We also performed neck ultrasound, neck MRi and 99mTc_MIBI scintigraphy with negative results. We performed again punction of the cyst, but the PTH level in the cyst fluid was lower (4173 pg/ml) than in serum (6915 pg/ml, normal range 13–50). When our patient became stable, without fever after antibiotic treatment, we performed left lateral thoracotomy with extirpation of the cyst. Parathyroid adenoma with cystic degeneration with residual atrophic thymic tissue was confirmed by histological examination. The serum calcium and also PTH are normalized after the surgery without any treatment and our patient is doing well.

Conclusion: We are presenting rare case of primary hyperparathyroidism caused by parathyroid adenoma with cystic degeneration, localized in mediastinum. Diagnostic of cyst in this localization can cause pitfalls.