著しい副甲状腺機能亢進を呈しながら術前画像診断が困難であった嚢胞性副甲状腺腺腫の１例

概要

Case : An 83-year-old woman visited a local physician with anorexia and weight loss for the past six months, and was referred to our hospital. Laboratory evaluation revealed corrected Ca2+ 12.2 mg/dl,iP 2.2 mg/dl, intact PTH 472.3 pg/ml, and FEca 2.8 %. Thus, the patient was diagnosed as having primary hyperparathyroidism (PHPT). Neck ultrasonography showed a 4 cm cystic lesion in the right lobe of the thyroid gland. This lesion had a “beak sign” with the thyroid gland on CT, suggesting it did not originate from the parathyroid gland. Further¬more, 99mTc-methoxy-isobutyl-isonitrile (MIBI) scintigraphy showed no accumulation. Thus, we could not diag¬nose the cystic lesion as the source of PHPT. After admission the corrected Ca2+ and intact PTH were per¬sistently elevated, which was difficult to control despite medical treatment. After consultation with an endocrine surgeon, surgical treatment was performed semi-urgently. A rapid intraoperative examination of the cyst fluid showed an intact PTH level of 593,500 pg/ml;the site was determined to be the cause of the disease. Pathology confirmed the diagnosis of cystic parathyroid adenoma.

Imaging tests for parathyroid tumors include neck ultrasound, CT, MRI, and MIBI scintigraphy. Still, in the case of large cystic lesions, it may be difficult to diagnose the lesion using these techniques. Even if the diagnosis of a parathyroid tumor is difficult to make based on imaging findings, aggressive surgical treatment should be con-sidered if the clinical findings are amenable to surgery. Shinshu Med J 70 /18 —194, 2022