Endocrine Abstracts

Parathyroid carcinoma (PC) is a rare endocrine tumor accounting for 0.5–6% or less in cases of primary hyperparathyroidism. According to The American Joint Committee on Cancer (AJCC) eighth edition, the histopathological criteria for PC include the presence of vascular invasion with capsular invasion and progression and/or metastasis to adjacent tissues. However, the small number of cases of PC makes it difficult to predict prognosis in the postoperative period of PC. We present two case report of PC: First, male patient, has chronic kidney disease in the dialysis stage and was monitored for PTH during his dialysis sessions. In September 2022 his PTH level was increase over 1911 pg/ml (15-65 pg/ml) and total calcium level corrected for albumin was 10.4 mg/dl. Because patient was also symptomatic (important bone pain), he was treated with total parathyroidectomy. Histopathological report was positive for right parathyroid carcinoma pT1NxL0V1Pn0 and Ki67 was positive in 5% of tumoral cells. Patient’s calcium level decreased after the surgery needing high calcium doses and alfacalcidol. His PTH level decrease to 554 pg/ml and his calcium level normalize with orally calcium scheme. In order to detect secondary lesions, patient underwent whole body MIBI scintigraphy with no metastasis found on functional imaging. Second patient is a female patient diagnosed with a thyroid hipoechoic nodule in left thyroid lobe, with increased PTH level over 847 pg/ml and high calcium level of 13 mg/dl admitted for functional parathyroid imaging with MIBI. Scintigraphy report showed left superior parathyroid adenoma with dimensions about 1.5 cm. She was operated (October 2022) and the histopathological report was positive for parathyroid carcinoma in left superior parathyroid area pT2N0L0V0Pn0R1 with local invasion in adipose tissue and muscular strap, with Ki67 positive in 4% of tumoral cells. Her PTH level also decreased after the surgery at 112 pg/ml and she was referred for radiotherapy treatment. Functional imaging after the surgery (WBS MIBI scintigraphy) didn’t found any distant secondary lesions. These case series of parathyroid carcinoma presents two different pictures: the initial diagnosis of secondary hyperparathyroidism vs primary hyperparathyroidism with no biological reason to think of parathyroid carcinoma vs many biological hints of parathyroid carcinoma, both successfully surgically treated, one with active monitoring and other with complementary radiotherapy treatment.