Cystic parathyroid adenoma with coexistent sarcoid granulomas

A 55-year-old woman with sarcoidosis developed hyperparathyroidism that was associated with fluctuating serum calcium levels. Ultrasonography and a computed tomography (CT) scan of the neck demonstrated a cystic lesion in the lower posterior area of the left thyroid lobe. Histological examination after subsequent surgery revealed sarcoid granulomas within a parathyroid adenoma. The pathogenesis of this rare association is discussed.