Endocrine Abstracts

Objective: To describe a patient with an unusual course of primary hyperparathyroidism (PHPT) due to parathyroid adenoma in 2004, who developed recurrent hyperparathyroidism due to parathyroid carcinoma in 2010, and a subsequent adenoma in 2011.To our knowledge, this sequential occurrence has not been previously reported in literature.

Case: A 57-year old male was operated on for a parathyroid adenoma in the right inferior gland in 2004. He was asymptomatic until six years later (2010), he was hospitalized due to hypercalcemia with markedly elevated parathyroid hormone level (intact PTH 520 pmol/L). Parathyroid scan showed increased uptake in the inferior right thyroidal bed. Radio-guided parathyroidectomy with intra-operative PTH assay was performed (pre-excision PTH 520,10 min post-excision 8.7, 6 in post-excision 3.77). A 2.3 cm parathyroid carcinoma of the right inferior and superior glands was found. Post-operatively, he developed hungry bone syndrome and was managed with calcium and vitamin D supplements. Upon discharge, ionized calcium level normalized.

In 2011, he developed recurrent hypercalcemia with low phosphorus and elevated intact PTH levels. Repeat parathyroid imaging showed a new lesion in the suprasternal notch. Recurrent and/or metastatic parathyroid carcinoma was primarily considered. However, re-exploration of the neck revealed a 1.5 cm parathyroid adenoma with lymph node negative for metastasis. (Pre-excision PTH 22.7, 10 min post-excision 7.26, 30 min post-excision 5.12). Post-operative ionized calcium was normal.

Conclusion: It is very rare for three independent episodes of PHP to be caused by different pathology in the same patient within a 7-year time frame. Recurrent PHP after resection of a parathyroid carcinoma does not necessarily indicate persistent or recurrent parathyroid carcinoma but can also be caused by a parathyroid adenoma. This underscores the necessity of adequate long-term follow-up to ensure early detection and management of parathyroid tumors.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

Histopathological section showing parathyroid carcinoma with blood vessel invasion (arrow) in 2010. H&E staining.