W014

 

Thoracic Surgery for Persistent Hyperparathyroidism due to Ectopically Located Parathyroid Tissue

 

A N Di Marco, J E Jackson, J R Anderson, F F Palazzo, Departments of Endocrine Surgery, Radiology & Cardiothoracic Surgery, Hammersmith Hospital, Imperial College Healthcare NHS Trust, London, UK

 

Failure to cure hyperparathyroidism (HPT) at the initial operation has an estimated incidence in the UK of 5.2%, rising to 15.4% nationally for re-operations.1 Ectopic glands including thoracic parathyroids are amongst the less common causes of failure to cure at first time surgery.2 The successful management of persistent and recurrent HPT requires close collaboration between the endocrinologist, radiologist and surgeon and with this, cure rates close to those for primary surgery may be achieved.3 However, as illustrated by this case series, ectopic thoracic disease presents particular challenges. 8 patients are presented who underwent re-operative parathyroid surgery for ectopic parathyroid glands in the thorax. One patient had renal HPT and all others, primary HPT with one MEN-related and the other 7 sporadic. Median age at reoperation was 43 years (range 18-65). The number of previous unsuccessful procedures was 1 in 6 cases, 2 in 1 case and 3 in 1 patient. The strategy in all cases was to (1)reconfirm the diagnosis with repetition of the biochemistry and confirm existence of an indication to intervene, (2)establish the details of previous intervention (based on operating notes and histology) (3)perform further selected imaging and (4)plan surgery with appropriate cardiothoracic surgeon back up where required. The ectopically located gland was identified on NM imaging in 3 cases, 1 with concordant USS and 2 with concordant CT/MRI and 5 patients had diagnostic venous sampling, 3 with concordant CT/MRI. The surgical approach was via median sternotomy in 4 cases, manubrial split in 2 and thoracoscopy in 2. Intraoperative PTH was used in all patients bar one, whose operation predated the availability of this technology. Intermittent monitoring of the recurrent laryngeal nerve was used selectively (in 4 cases). A single abnormal gland was removed in all cases except one in whom a full mediastinal clearance was performed (based on venous sampling) with no parathyroid tissue detected histologically. In this patient the calcium normalized, as did PTH initially, before rising to 8.8pmol/l by 4 months (in the context of a corrected calcium of 2.48mmol/l and vitamin D of 47.8nmol/l). Histology confirmed abnormal parathyroid tissue in all but the case above. A further equivocal result was seen in the renal HPT case, where the PTH decreased by over 50% intraoperatively but remained elevated at long term follow up with eucalcaemia. 6 patients had definite biochemical cure, although 2 had not yet reached 6 month follow-up and 2 were rendered predictably or intentionally hypoparathyroid (3 gland excision in one patient and subtotal excision for MEN in the other at previous surgery). This small series illustrates the challenges in re-interventions for persistent HPT due to thoracic disease which include: (1) the difficulty in achieving accurate pre-operative anatomical localization, (2) the intraoperative localization of a small gland in a large fat filled cavity and (3) the decision to induce hypoparathyroidism as the only way to achieve cure in some cases something that the arrival of recombinant PTH may avert.

 

 

References:

1. Chadwick et al. Fourth National Audit Report. The British Association of Endocrine and Thyroid Surgeons. 2012.

2. Phitayakorn R, McHenry CR. Incidence and location of ectopic abnormal parathyroid glands. American Journal of Surgery. 2006. p. 41823.

3. McIntyre CJ et al. Patterns of disease in patients at a tertiary referral centre requiring reoperative parathyroidectomy. Ann R Coll Surg Engl. 2015;97(8):598602.