Endocrine Abstracts

Introduction: Parathyroid carcinoma represents a very rare cause of primary hyperparathyroidism. It can be sporadic (most of cases), but also can occur in association with certain syndromes (multiple endocrine neoplasia, hyperparathyroidism-jaw tumor syndrome or isolated familial hyperparathyroidism).

Case report: An 18-year-old woman was referred to the endocrine clinic because of a severe hypercalcemia, detected in the orthopedic surgery department, where she was hospitalized for surgical correction of a frailty right hip and femur fracture. For a few months, she has been complaining of muscle and bone pain (particularly at the left lower limb) and decreased muscle strength; also, her past medical history included a left thyroid nodule and a hypercalcemia of 13.54 mg/dl two years before, that was not further investigated. At admission, she had a PTH of 1157 pg/ml (NV: 15-65), a calcium of 14.7 mg/dl, a low phosphorus (2 mg/dl), and a 25-OH-vitamin D of 21 ng/ml (NV: 30-100), with normal thyroid and renal function. The diagnosis of primary hyperparathyroidism was established. The values for calcitonin and metanephrines were within the normal range, ruling out MEN 2 syndrome. Also, the normal value for chromogranine A and the absence of clinical features of a pituitary adenoma made the MEN 1 syndrome unlikely. A neck ultrasound revealed 2 hypoechoic nodules, one within the left thyroid lobe and another located under the lobe. A neck and thoracic CT scan showed a left lateral cervical, paratracheal, heterogenous mass of 4.313.233.17 cm, possibly a parathyroid tumor. RX scans of the left lower limb revealed brown tumors. An abdominal US was performed and showed kidney stones, without nephrocalcinosis. After fluid therapy for hypercalcemia, it was performed an “en bloc” resection of the left paratracheal mass and left thyroid lobe. The histological and immunohistochemical studies confirmed 3 foci of parathyroid carcinoma, pT3pN0, with vascular invasion, with positivity for the expression of GATA3, chromogranin A, PTH and parafibromin. Also, genetic testing for hyperparathyroidism-jaw tumor syndrome (HRPT2/CDC73 germline mutation) and MEN 1 gene sequencing have been taken into consideration. After surgery, the PTH dropped to 4.46 pg/ml, with a calcium of 10.5 mg/dl. Then, the patient developed “hungry bone syndrome” and hypothyroidism, necessitating high doses of vitamin D and calcium supplements and L-thyroxine substitution. She had a favorable evolution, with fractures consolidation, PTH and calcium within the normal range and without other signs of tumor recurrence at more than 2 years after parathyroid carcinoma resection.