Endocrine Abstracts

Case history

A 23-year-old woman with no significant past medical history and normal renal function was incidentally found to be hypercalcaemic in 2003. Following investigation, she was diagnosed with primary hyperparathyroidism. She underwent three-gland parathyroidectomy; histology demonstrated hyperplasia. Her bone function remained normal, but 4 years later she was found to have normocalcaemic hyperparathyroidism. Sestamibi demonstrated uptake inferior to the left thyroid lobe and in a 0.7cm right cervical nodule, and she became increasingly hypercalcaemic. Histology following further surgical resection showed parathyroid hyperplasia. Her corrected calcium failed to normalise post-operatively, and repeat Sestamibi in 2009 showed ongoing uptake at the site of the removed cervical nodule and in the superior mediastinum. She continued to be reviewed and her corrected calcium continued to rise. In 2014 she underwent venous sampling, which suggested parathyroid activity lateral to the right carotid artery. Three nodules, again displaying hyperplasia, were removed from the carotid sheath. Her calcium and PTH remained persistently elevated. A trial of cinacalcet was started, but the patient was unable to tolerate because of extreme nausea.

Investigations

CT Chest, MRI neck & Sestamibi (2008): 7 mm enhancing nodule lying just anteromedial to the right jugular vein. Histology: Circumscribed without infiltration but with fibrous septa. No mitotic activity. Microacinar appearance, consistent with parathyroid hyperplasia. Calcium/Creatinine Clearance Ratio (2012): 0.027 mmol/mmol (vitamin D 85 nmol/l). Genetics: MEN1 and HRPT2 negative. Venous sampling (2014) – Highest PTH level obtained from laterally originating tributary of the right internal jugular vein (211 pmol/l). Sestamibi 2017: uptake in the left thyroid lobe and a 10mm nodule superolateral to the right thyroid. Since January 2019: corrected calcium 2.6 – 2.82 mmol/l, and PTH: 16.7–23 pmol/l.

Results/Treatment

Our patient underwent her fourth and final surgery in 2017 with an extensive neck dissection. Histology was again consistent with multiple small foci of hyperplastic parathyroid tissue. Our surgical team feel that there are no further surgeries that they would consider appropriate. She continues to feel very symptomatic but is reluctant to trial further cinacalcet.

Conclusion/Points for discussion

Parathyromatosis secondary to primary hyperparathyroidism is exceptionally rare, with only 22 cases reported in the literature. There are several theories of how it may develop: low-grade parathyroid carcinoma, implantation into surrounding tissue during surgery and stimulation of embryological remnants of parathyroid tissue. Despite multiple surgeries this patient remains symptomatic and cinacalcet, although previously not tolerated, is the only available therapeutic option.