Endocrine Abstracts

Parathyroid carcinoma is a rare cause of primary hyperparathyroidism. Clinical suspicion is determined by the severity of hyperparathyroidism associated or not with palpable cervical tumor and local invasion when surgery.

Case report: A 45-year-old woman without any previous history of kidney stones or fractures. Admitted to hospital because of high hypercalcemia (calcium 15.1 mg/dl), fatigue and generalized arthralgia. Physical examination revealed right thyroid nodule about 3 cm. Cervical ultrasound: RTL nodule 3×2 cm without lymphadenopathy. Sestamibi Scintigraphy-CT enhanced uptake at this level suggestive of right parathyroid adenoma. Biochemistry revealed PTH 548 pg/dl, Calcium 10.9 mg/dl, phosphorus 1.76 mg/dl, vitamin D 7.71 ng/ml, creatinine 0.9 mg/dl. Renal ultrasound: emerging nephrocalcinosis. DEXA scan showed osteoporosis. Primary severe hyperparathyroidism was suspected. She was referred to neck surgery team, performed right hemithyroidectomy. Histopathology revealed 3.2 cm parathyroid carcinoma infiltrating thyroid and adjacent adipose tissue, with 5% ki 67 and free disease surgical borders. After surgery: PTH 42.11 pg/ml, Calcium 8.6 mg/dl, Phosphorus 2.89 mg/dl, vitamin D 10.5 ng/ml and TSH 7.22 μUI/ml. She started bisphosphonate therapy, calcifediol and levothyroxine 50 μg/day. Neck US showed right thyroid lobectomy without thyroid remnants or suspicious lymphadenopathy. Subsequent blood tests displayed hypocalcemia and hypophosphoremia, suggestive of ‘hungry bone syndrome’, started treatment with calcium carbonate and calcitriol. Genetic testing for HRPT2 was requested with negative result and PET-CT didn’t evidence active neoplasic disease.

Conclusion: The fast decrease of serum calcium after surgery is consider as a surgical marker of success. It is also risk factor for developing ‘hungry bone syndrome’. Because of possibility of recurrence to medium-long term, they require lifelong surveillance. The possible association of parathyroid carcinoma with jaw ossifying fibromass been rejected due to the negative result on genetic study.