Unexpected remission of hyperparathyroidism caused by hemorrhage due to the use of fine-needle aspiration biopsy: two cases report.

Hyperparathyroidism is not a rare disease; if a parathyroid adenoma is confirmed, the treatment of choice is the surgical resection. Diagnostic use of fine-needle aspiration biopsy (FNAB) for histological confirmation in patients with hyperparathyroidism is controversial. And spontaneous remission of hyperparathyroidism caused by bleeding or infarction of the adenoma rarely occurs. Here we have reported two cases of hyperparathyroidism in which spontaneous remission occurred due to the use of FNAB for diagnosis. The remission was confirmed after surgical removal and pathological review of the adenoma. The first patient diagnosed with primary hyperparathyroidism (PHPT) had neck pain and severe swelling 4 days after FNAB, and spontaneous remission due to intracapsular hemorrhage was confirmed after surgery. In the second patient receiving hemodialysis treatment for end-stage renal disease, hyperparathyroidism spontaneously resolved after FNAB and the parathyroid hormone (PTH) levels normalized after surgery. The first patient maintained a normal level of PTH for 6 years, and the second patient received kidney transplantation 6 years after surgery, and the normal level of PTH was confirmed for 13 years. Caution is needed while performing FNAB for diagnosis of hyperparathyroidism and during decision making regarding whether to observe the patient or perform surgery after spontaneous remission due to bleeding or infarction.