Endocrine Abstracts

Recurrent hyperparathyroidism (HPT) refers to reappearance of hypercalcemia after a normocalcemic period of at least 6 months post-parathyroidectomy. Parathyroid carcinoma is a rare cause of primary hyperparathyroidism (pHPT), accounting for 0.4–5.2% of cases. Parathyromatosis is defined as small nodules of hyperfunctioning parathyroid tissue scattered in the soft tissues of the neck and/or mediastinum. We describe two cases with recurrent hypercalcemia after surgical interventions for pHPT.

Case 1: A male patient, MI, 47 yo, had recurrent hypercalcemia despite three parathyroidectomies. At first presentation, his labs were Ca=15.4 mg/dl, PTH=340 pg/ml. Sestamibi parathyroid scintigraphy and MRI scan of the neck showed an upper left parathyroid adenoma. It was removed in 2012 and pathology was consistent with adenoma. He remained normocalcemic for 3 years, and then his hypercalcemia recurred. The patient underwent surgery for the second time, when unfortunately the recurrent left nerve was accidentally cut. In November 2016, he underwent a third surgical neck exploration and pathology indicated a parathyroid carcinoma. Postoperatively, the calcium was within the normal range for 3 months. At the last evaluation in 2017, Ca=12.3 mg/dl, PTH=219.5 pg/ml (NR:7.5–53.5). MRI scan showed two nodules: one located left paratracheal area and one behind the left sternocleidomastoid muscle. He began medical management with alendronate and the fourth surgery was scheduled.

Case 2: A male patient, IB, 45 yo, was admitted in our Clinic in May 2017, due to recurrent hyperparathyroidism. Laboratory data when patient was diagnosed with pHPT for the first time indicated Ca=14.4 mg/dl, PTH=2000 pg/ml due to a lower left parathyroid adenoma. He was operated in 2012 and adenoma was confirmed by pathology. After 5 years he presents with: Ca=16.7 mg/dl, PTH=5000 pg/ml (NR:12–65). Sestamibi parathyroid scintigraphy and ultrasound exam showed recurrence. He underwent surgery for the second time and pathology indicated a parathyroid carcinoma. Both patients were males, with benign disease after first surgery and without any renal disease. None of them presented local or distant metastasis. Regarding the origin of parathyromatosis there are three theories we took into account: it is a low-grade parathyroid malignancy, it results from seeding of the parathyroid tissue during surgery for pHPT or it is an overgrowth of an embryologic rest. In conclusion, in some cases, it should make a distinction between a locoregional metastatic parathyroid carcinoma with multiple implants and paratyromatosis.