[The 520th case: neck swelling, hypocalcemic convulsions, and spontaneous hemorrhage of a cystic parathyroid adenoma].

A 33-year-old man was admitted with a 4-day history of neck swelling and intermittent convulsions for 3 days. Physical examination revealed a soft, tender nodule measuring~4 cm×3 cm in the right lobe of the thyroid gland. Chvostek's and Trousseau's signs were positive. Laboratory tests revealed hypocalcemia, normal serum phosphorus and magnesium levels, elevated parathyroid hormone (PTH) levels, and reduced vitamin D levels. Bone turnover markers indicated active bone formation, and bone density testing revealed severe osteoporosis. Neck ultrasound and CT suggested a thyroid-origin mass; however, 99Tcm-MIBI parathyroid scintigraphy was negative. A review of the previous thyroid ultrasound of the patient revealed a hypoechoic nodule on the dorsal side of the right lobe suspected to represent a parathyroid adenoma, along with elevated blood calcium levels. Combined with the significantly elevated PTH levels detected in the aspirate from the neck mass, these findings led to a final diagnosis of primary hyperparathyroidism, cystic degeneration and hemorrhage of a parathyroid adenoma, hungry bone syndrome, secondary osteoporosis, and vitamin D deficiency. After correcting the hypocalcemia, the patient underwent endoscopic resection of the parathyroid lesion. Postoperatively, serum PTH levels decreased significantly, blood calcium levels normalized, and no further convulsions occurred.