Parathyroid Surgery - Special Situations
1. Single adenoma: Removal of the adenoma will cure the patient; the vogue in the past to remove normal parathyroids is unnecessary and risks permanent hypoparathyroidism. Careful biopsy of a normal gland is helpful in confirming single gland disease. Over the years I have become less inclined to biopsy obviously normal glands, but do believe that if a classical open operation is performed that all four parathyroid glands should be inspected (This view is changing with Intra-operative PTH sampling).
2. Parathyroid Hyperplasia: This is always a difficult condition to treat. The hyperplasia may affect 2 or more glands. In this condition extra glands are common and routine cervical thymectomy is mandatory. The purist will aim to have a normocalcaemic patient with no calcium or vitamin supplements. This can be achieved by either subtotal parathyroidectomy leaving 100mgs of tissue in situ or by parathyroid transplantation. Over the years I have not been convinced that the results are as good as was originally thought. It may be that my tertiary referral practice highlights the problems, but a considerable amount of my work is re-exploring failed hyperplasia cases. I would make the following points:
- If undertaking parathyroid transplantation, make sure that all parathyroid tissue has been excised - I consider intra-operative parathyroid estimation is now mandatory. There is no more difficult situation to sort out than graft dependant recurrent hyperparathyroidism with missed functional parathyroid tissue in the neck or mediastinum.
- If undertaking sub-total parathyroidectomy, remove 3 glands and leave 100mgs of parathyroid tissue. Leave a gland that lies well away from the recurrent laryngeal nerve and mark it with a titanium clip. Remember that there is a significant recurrence rate over the years.
- My own view is somewhat pragmatic. I consider that the treatment of choice for patients under 50 with or without severe hypercalcaemia, and for patients over 50 with severe hypercalcaemia, is total parathyroidectomy with calcium and vitamin D supplementation. The supplementation is no great hardship and very easy to control. I believe this policy is mandatory in the MEN 1 syndrome where it is so important that the parathyroid aspect of the disease is under perfect control. I believe that patients over 50 with moderate hypercalcaemia who are not MEN 1 should undergo subtotal parathyroidectomy.
3. Double adenoma: One should be very cynical about this situation; asymmetric hyperplasia can look just like this. Estimate the weight and size of the normal parathyroids; perform frozen section on the enlarged glands and on the biopsies of the normal glands. If the pathology indicates double adenoma remove the enlarged glands and leave the normal ones. If there is the suggestion of asymmetric hyperplasia treat as suggested for standard hyperplasia.
4. Parathyroid cancer: Most cases of parathyroid cancer are functional, the clues to the diagnosis being a very high calcium, young age, a mass in the neck, voice change and of course evidence of metastases.We have come across 2 separate situations:
#A.Following removal of a single adenoma that appeared benign at surgery the final sections suggest malignancy (both calcium and parathyroid hormone levels having returned to normal.) I suggest that in these cases the patient is re-explored and an ipsilateral thyroidectomy is performed with meticulous clearance of the local areolar tissue and lymph nodes. I would also add external beam radiotherapy to the operative field. I realize this is a very aggressive approach but the results once the disease has recurred are very poor.
#B.In a patient with severe hypercalcaemia where a hard mass is found, the mass itself and the ipsilateral thyroid and local lymph nodes should all be excised en-bloc, if necessary sacrificing the recurrent laryngeal nerve. Postoperative external beam radiotherapy should be used, even though there is thought to be complete clearance of the tumour. Chemotherapy is of little value. Most deaths are due to uncontrollable hypercalcaemia resistant to biphosphonates.
5. A solitary parathyroid micro adenoma is very rare, is found in previously explored cases and is a minute highly active tumour within a normal sized parathyroid gland. Excision is curative. I have seen less than a handfull in 30years of endocrine surgical practice.
6. Disrupted parathyroid: When exploring patients with recurrent hyperparathyroidism, one may find small millet seed sized nodules at the site of the previous parathyroidectomy. These nodules are minute pieces of parathyroid that have broken off the parathyroid tumour and grown. They must be completely excised with the surrounding thyroid tissue and any involved muscle.