The anatomic basis of parathyroid surgery

Heart failure in hypophosphatemic rickets: complications from high-dose phosphate therapy

OBJECTIVE

To report a rare case of hypophosphatemic rickets (HR) leading to extensive cardiac complications.

METHODS

We present the clinical course and autopsy findings of a patient with HR, treated with chronic phosphate-only therapy as a child, who subsequently developed tertiary hyperparathyroidism leading to extensive cardiac calcifications and complications. We also review the literature on the pathophysiology of calcifications from HR.

RESULTS

A 34-year-old man was diagnosed with HR at 4 years of age after presenting with growth delay and leg bowing. Family history was negative for the disease. He was initiated on high-dose phosphate therapy (2-6 g of elemental phosphorus/day) with sporadic calcitriol use between 4-18 years of age. For 6 years he received phosphate-only therapy. Subsequently, he developed nephrocalcinosis, heart valve calcifications, severe calcific coronary artery disease, heart block, and congestive heart failure. At a young age, he required an aortic valve replacement and a biventricular pacemaker that was subsequently upgraded to an implantable cardioverter defibrillator. Autopsy showed extensive endocardial, myocardial, and coronary artery calcifications.

CONCLUSION

Cardiac calcification is a known sequela of tertiary hyperparathyroidism when it occurs in patients with renal failure, but it is rarely seen in HR due to high phosphate therapy. Phosphate alone should never be used to treat HR; high doses, even with calcitriol, should be avoided. It is important to be cognizant of high-dose phosphate effects and to consider parathyroidectomy for autonomous function, if needed. This case emphasizes the importance of appropriate therapy, monitoring, and management of patients with HR.

Incidence and localization of ectopic parathyroid adenomas in previously unexplored patients

BACKGROUND

Parathyroidectomy has a success rate of >95 % for cure of primary hyperparathyroidism. In about 6-16 % of cases, one or more hyperfunctioning parathyroid gland(s) are found in an ectopic location. Accurate preoperative imaging can aid in detecting these ectopically located glands and allow a focused surgical approach with an even higher success rate. The objective of this study was to assess the utility of ultrasonography (US) and technetium-99m-sestamibi (MIBI) scans in locating ectopic parathyroid glands in previously unexplored patients who presented with primary hyperparathyroidism.

METHODS

We analyzed a total of 1,562 patients who underwent surgery for hyperparathyroidism at our institution from 2000 to 2010. Ectopic parathyroid adenomas were identified in 346 of the patients (22 %). Of the 346 patients, we excluded 144 who underwent reoperations, had four-gland hyperplasia or were missing imaging details. We carefully reviewed the data, including demographics, laboratory values, preoperative localizing imaging details, and operative findings. Preoperative US and MIBI results were compared to the intraoperative findings.

RESULTS

We analyzed 202 patients with ectopic glands for accuracy of preoperative localization. Of these 202 patients, a single adenoma was the most common (89 %) followed by double adenoma (11 %). The ectopic parathyroid glands were predominantly located in the thymus (38 %) followed by 31 % in the retroesophageal region; 18 % were intrathyroidal. Preoperative MIBI scans had a sensitivity of 89 % (161/197), whereas US had a sensitivity of 59 % (35/63) for detecting ectopic glands. Overall, both imaging modalities had a positive predictive value of 90 %, with MIBI correctly predicting ectopic glands best in the thymus, mediastinum, or the retroesophageal space, and US was most accurate at detecting intrathyroidal glands.

CONCLUSIONS

Based on the data available at our institution, MIBI has a higher sensitivity than US in correctly localizing ectopic parathyroid adenomas, but the accuracy of detection varies based on location. Both imaging techniques have a high PPV for detecting an ectopic gland. Therefore, imaging with MIBI and US can be complementary, and positive localization of an ectopic gland with either modality is highly accurate and can facilitate a more focused surgical approach.

Mechanisms of thyroid development and dysgenesis: an analysis based on developmental stages and concurrent embryonic anatomy

Thyroid dysgenesis is the most common cause of congenital hypothyroidism that affects 1 in 3000 newborns. Although a number of pathogenetic mutations in thyroid developmental genes have been identified, the molecular mechanism of disease is unknown in most cases. This chapter summarizes the current knowledge of normal thyroid development and puts the different developmental stages in perspective, from the time of foregut endoderm patterning to the final shaping of pharyngeal anatomy, for understanding how specific malformations may arise. At the cellular level, we will also discuss fate determination of follicular and C-cell progenitors and their subsequent embryonic growth, migration, and differentiation as the different thyroid primordia evolve and merge to establish the final size and shape of the gland.

Adenomas of cervical maldescended parathyroid glands: pearls and pitfalls

BACKGROUND

Missed parathyroid adenoma (PTA) is the commonest cause of persistent hyperparathyroidism. Although many are subsequently found in well-described locations, some are found in unusual regions of the neck. This paper presents the combined experience of three large tertiary endocrine surgery centres with maldescended PTA (MD-PTA).

METHODS

Patients were recruited from the endocrine surgical databases of three tertiary endocrine surgery units. Patients with PTA found >1 cm above the superior thyroid pole or other cervical locations as a result of abnormal or incomplete descent were included for analysis.

RESULTS

MD-PTA was identified in 16 patients out of a total of 5241 patients who had undergone parathyroidectomies in the 7-year study period (incidence 0.3%). Seven (44%) patients had minimally invasive parathyroidectomy, while nine (56%) had bilateral neck exploration. The mean excised gland weight was 750 + 170 mg. Cure was achieved in all patients with a minimum follow-up of 6 months. The locations of MD-PTA in this study included submandibular triangle, retropharyngeal space, carotid sheath (at carotid bifurcation and intravagal), parapharyngeal space (superior to thyroid cartilage or superior thyroid pole) and cricothyroid space.

CONCLUSIONS

Despite their rare occurrence, incompletely or abnormally descended PTAs can be encountered by any surgeon who performs parathyroidectomies. It is important to develop a strategy to systematically locate these glands. High cure rates can still be achieved with minimally invasive parathyroidectomy if confident preoperative localization is available. A sound knowledge of embryology and a thorough exploration also facilitate an overall high success rate with open exploration.

Persistent primary hyperparathyroidism: an uncommon location for an ectopic gland - Case report and review

Primary hyperparathyroidism (PHPT) is a common endocrine disorder that mainly affects middle-aged women. Patients are usually asymptomatic. The disease might be ascribable to hyperplasia, carcinoma, and single or multiple adenomas. PHPT may be sporadic or familial, the latter comprising multiple endocrine neoplasia type 1 or 2A, familial benign hypocalciuria hypercalcemia, and hyperparathyroidism-jaw tumor syndrome. The most common causes for persistent PHPT are multiglandular disease, and missed abnormal ectopic or orthotopic parathyroid glands. Imaging localization studies should precede a new surgical intervention. Ectopic parathyroid glands are rarely located at the aortopulmonary window. For diagnosis confirmation, 99mTc-sestamibi SPECT/CT seems to be an advantageous test. Another possibility is to perform 99mTc-sestamibi followed by thoracic CT or MRI. Parathyroidectomy may be performed by means of median sternotomy, thoracotomy, or video-assisted thoracoscopy. We describe a case of persistent primary hyperparathyroidism due to the presence of an ectopic parathyroid gland found at the aortopulmonary window. As the investigation necessary to clarify the etiology of recurrent nephrolithiasis proceeded, the diagnosis of PHPT was determined. The patient underwent subtotal parathyroidectomy; nevertheless, PHPT persisted. Genetic syndromes that could account for this condition were excluded. Imaging studies available at that time were not able to locate abnormal glands; moreover, the patient refused to undergo surgical exploration. Later, the patient underwent 99mTc-sestamibi SPECT/CT, which revealed a parathyroid gland at the aortopulmonary window.

[Zuckerkandl's tubercle. Location, shape and dimensions]

INTRODUCTION AND OBJECTIVE

Although Zuckerkandl's tubercle is not known by many head and neck surgeons, it is a fundamental surgical anatomical detail, already described in the nineteenth century. Its detection is of great importance as the reference in the search for the recurrent nerve and superior parathyroid gland.

MATERIAL AND METHOD

We designed a prospective study to analyse the posterolateral border of thyroid lobes, looking for this tubercle. We included 107 thyroidectomies performed by the same surgeon; 88 were total thyroidectomies (82.24%) and 19 hemithyroidectomies (17.75%), with dissection of a total of 195 thyroid lobes. Zuckerkandl's tubercle should be sought by displacing the posterolateral margin of the thyroid lobes.

RESULTS

It was reliably detected in 155 thyroid lobes (79.48%). The mean tubercle dimensions were 11 mm transverse axis and 9 mm longitudinal axis. The shape of the Zuckerkandl's tubercle was sessile (70.96%) or pedunculated (29.03%). In the 5.80% of cases, the Zuckerkandl's tubercle distal end was bifid. We did not find a Zuckerkandl's tubercle individualised as an ectopic thyroid (0.00%). Zuckerkandl's tubercle was more frequent in the right thyroid lobe (P=.06).

CONCLUSION

Zuckerkandl's tubercle is recognised by its location, shape and dimensions.

Imaging techniques in parathyroid surgery for primary hyperparathyroidism

As more patients present with the incidental diagnosis of primary hyperparathyroidism due to biochemical screening, treatment guidelines have been developed for the treatment of hyperparathyroidism. Management of primary hyperparathyroidism has evolved in recent years, with considerable interest in minimally invasive approaches. Successful localization of the diseased gland(s) by nuclear imaging and anatomical studies, along with rapid intraoperative parathyroid hormone assay, has allowed for focused and minimally invasive surgical approaches. Patients in whom the localization studies have identified single-gland adenoma or unilateral disease are candidates for such focused approaches instead of the traditional approach of bilateral exploration. These imaging techniques have also been critical in the successful management of patients with persistent or recurrent disease.

An unusual ectopic location of a parathyroid carcinoma arising within the thyroid gland

INTRODUCTION

Parathyroid carcinomas are very rare tumors and may arise in the normally located or ectopic gland. The latter present certain diagnostic difficulties, and there are no specific guidelines on their management. We present a case of parathyroid carcinoma arising within an ectopically located intrathyroid gland and discuss the diagnosis, management, and difficulties encountered. Furthermore, we review all six previously reported cases of this rare event and demonstrate the patterns in presentation, as well as the differences in management.

CASE PRESENTATION

A 39-yr-old male presented with a right neck mass with biochemical derangement suggestive of a parathyroid lesion. However, radiological investigations were inconclusive as to the true nature of this lesion because they demonstrated a mass within the right thyroid lobe. A sestamibi (99m)technetium subtraction study was performed, which suggested an intrathyroid parathyroid carcinoma. The patient underwent successful surgical intervention.

CONCLUSION

Although rare, ectopically located parathyroid glands can harbor malignant disease. Those located within the thyroid gland can be difficult to diagnose, and thus a combination of radiological modalities, including sestamibi (99m)technetium studies, need to be utilized. Although surgical resection is the most effective treatment, there are no specific guidelines as to the radicality of such treatment.

Initial parathyroid surgery in 606 patients with renal hyperparathyroidism

BACKGROUND

The aim of the present study was to evaluate the outcome of different surgical procedures for patients on permanent dialysis who underwent initial parathyroidectomy for renal hyperparathyroidism (rHPT).

METHODS

Out of a prospective database of patients who underwent parathyroid surgery for rHPT between 1976 and 2009, patients on permanent dialysis who underwent initial parathyroidectomy were further analyzed regarding perioperative biochemical changes and postoperative outcome.

RESULTS

A total of 606 patients were analyzed. Total parathyroidectomy with autotransplantation (group A) was performed in 504 patients, total parathyroidectomy without autotransplantation in 32 (group B), subtotal parathyroidectomy in 21 (group C), and incomplete parathyroidectomy in 49 (group D). After surgery, mean calcium levels dropped from 2.76 to 1.91 mmol/l in group A, from 2.67 to 2.11 mmol/l in group B, from 2.70 to 2.09 mmol/l in group C, and from 2.65 to 1.94 mmol/l in group D. The parathyroid hormone level dropped from 1,371.4 pg/ml to 28.8 pg/ml in group A, from 1,078.4 pg/ml to 27.0 pg/ml in group B, from 2,377.9 pg/ml to 61.4 pg/ml in group C, and from 1,010.2 pg/ml to 99.5 pg/ml in group D. Persistent rHPT occurred in 2/504 patients from group A (0.4%), 0/32 patients from group B (0%), 1/21 patients from group C (4.8%), and 2/49 patients from group D (4.1%). After a mean follow-up of 57.6 months, recurrent rHPT occurred in 27/504 patients from group A (5.4%), in 0/32 patients from group B (0%), in 2/21 patients from group C (9.5%), and in 3/49 patients from group D (6.1%).

CONCLUSIONS

Total parathyroidectomy with or without autotransplantation is a feasible and safe surgical procedure for patients on permanent dialysis with otherwise uncontrollable rHPT.

Surgical approach in patients with hyperparathyroidism in multiple endocrine neoplasia type 1: total versus partial parathyroidectomy

Usually, primary hyperparathyroidism is the first endocrinopathy to be diagnosed in patients with multiple endocrine neoplasia type 1, and is also the most common one. The timing of the surgery and strategy in multiple endocrine neoplasia type 1/hyperparathyroidism are still under debate. The aims of surgery are to: 1) correct hypercalcemia, thus preventing persistent or recurrent hyperparathyroidism; 2) avoid persistent hypoparathyroidism; and 3) facilitate the surgical treatment of possible recurrences. Currently, two types of surgical approach are indicated: 1) subtotal parathyroidectomy with removal of at least 3-3 K glands; and 2) total parathyroidectomy with grafting of autologous parathyroid tissue. Transcervical thymectomy must be performed with both of these procedures. Unsuccessful surgical treatment of hyperparathyroidism is more frequently observed in multiple endocrine neoplasia type 1 than in sporadic hyperparathyroidism. The recurrence rate is strongly influenced by: 1) the lack of a pre-operative multiple endocrine neoplasia type 1 diagnosis; 2) the surgeon's experience; 3) the timing of surgery; 4) the possibility of performing intra-operative confirmation (histologic examination, rapid parathyroid hormone assay) of the curative potential of the surgical procedure; and, 5) the surgical strategy. Persistent hyperparathyroidism seems to be more frequent after subtotal parathyroidectomy than after total parathyroidectomy with autologous graft of parathyroid tissue. Conversely, recurrent hyperparathyroidism has a similar frequency in the two surgical strategies. To plan further operations, it is very helpful to know all the available data about previous surgery and to undertake accurate identification of the site of recurrence.

Primary hyperparathyroidism in multiple endocrine neoplasia type 1: when to perform surgery?

Primary hyperparathyroidism is a common endocrinological disorder. In rare circumstances, it is associated with familial syndromes, such as multiple endocrine neoplasia type 1. This syndrome is caused by a germline mutation in the multiple endocrine neoplasia type 1 gene encoding the tumor-suppressor protein menin. Usually, primary hyperparathyroidism is the initial clinical expression in carriers of multiple endocrine neoplasia type 1 mutations, occurring in more than 90% of patients and appearing at a young age (20-25 years). Multiple endocrine neoplasia type 1/primary hyperparathyroidism is generally accompanied by multiglandular disease, clinically manifesting with hypercalcemia, although it can remain asymptomatic for a long time and consequently not always be recognized early. Surgery is the recommended treatment. The goal of this short review is to discuss the timing of surgery in patients when primary hyperparathyroidism is associated with multiple endocrine neoplasia type 1.

Thyroid surgery

Diseases of the thyroid are common and surgical treatment is often the preferred option. Thyroid surgery is becoming subspecialised and falls within the repertoire of maxillofacial, and head and neck surgeons. Multidisciplinary management of most patients with diseases of the thyroid is key to providing the best care particularly for those with malignancies and retrosternal extension. To reduce postoperative complications a meticulous search for, and protection of the recurrent laryngeal nerve and parathyroid glands, with an incision along the skin crease in the lower neck, which can be extended for neck dissection, are paramount. Recent advances in thyroid surgery include ultrasound-guided cervical plexus block, use of the Harmonic Scalpel(®) (Ethicon Endo-Surgery, Inc., USA), intraoperative nerve stimulation to monitor the recurrent laryngeal nerve, use of TissuePatch™ 3 (Tissuemed Ltd., Leeds, UK) adhesive sealant, and minimal access surgery.

Localization of Small Parathyroid Adenomas Using Modified 4-Dimensional Computed Tomography/Ultrasound

Objective. To investigate whether parathyroid gland weight has an impact on the accuracy of preoperative localization of parathyroid adenomas with modified 4 dimensional computed tomography/ultrasound. And to determine if the weight of parathyroid adenomas can be calculated accurately based on the dimensions of the gland on the CT images.

Study Design. Case series with chart review.

Setting. Tertiary care hospital.

Subjects and Methods. One hundred forty-two patients who had a preoperative modified 4-dimensional computed tomography/ultrasound and underwent parathyroidectomy for hyperparathyroidism due to a parathyroid adenoma between 1998 and 2009. Charts were reviewed to identify (1) the sensitivity and specificity for localization of parathyroid adenomas according to gland weight and (2) correlation between preoperative estimate of parathyroid weight and the surgical weight of the parathyroid gland.

Results. Modified 4-dimensional computed tomography/ultrasound displayed 92% sensitivity for localizing adenomas weighing <150 mg to the correct side of the neck (95% confidence interval [CI], 65%-99%), 100% sensitivity for glands weighing 150 to 500 mg (95%-100%), and 98% sensitivity for glands weighing >500 mg (92%-100%). For localization to the correct quadrant of the neck, sensitivity was 75% (95% CI, 47%-91%) for glands weighing <150 mg, 89% (79%-95%) for those weighing 150 to 500 mg, and 94% (85%-97%) for glands weighing >500 mg. A positive correlation was seen between the preoperative weight estimate based on imaging and the operative weight of the gland, with a Pearson correlation coefficient of 0.96.

Conclusion. Modified 4-dimensional computed tomography/ultrasound can closely predict the weight of parathyroid glands preoperatively and has good sensitivity for localization of adenomas, even in glands weighing less than 150 mg.

The role of prophylactic central neck dissection in differentiated thyroid carcinoma: issues and controversies

Prophylactic central neck dissection (pCND) in differentiated thyroid carcinoma (DTC) is one of the most controversial surgical subjects in recent times. To date, there is little evidence to support the practice of pCND in patients with DTC undergoing total thyroidectomy. Although the recently revised American Thyroid Association (ATA) guideline has clarified many inconsistencies regarding pCND and has recommended pCND in “high-risk” patients, many issues and controversies surrounding the subject of pCND in DTC remain. The recent literature has revealed an insignificant trend toward lower recurrence rate in patients with DTC who undergo total thyroidectomy and pCND than those who undergo total thyroidectomy alone. However, this was subjected to biases, and there are concerns whether pCND should be performed by all surgeons who manage DTC because of increased surgical morbodity. Performing a unilateral pCND may be better than a bilateral pCND given its lower surgical morbidity. Further studies in this controversial subject are much needed.

Frequency of ectopic and supernumerary intrathymic parathyroid glands in patients with renal hyperparathyroidism: analysis of 461 patients undergoing initial parathyroidectomy with bilateral cervical thymectomy

BACKGROUND

The frequency of intrathymic parathyroid glands (IPGs) in patients undergoing parathyroidectomy for renal hyperparathyroidism (rHPT) varies considerably between 14.8% and 45.3%. Total parathyroidectomy with autotransplantation and subtotal parathyroidectomy are the most accepted surgical procedures to treat patients with rHPT. However, routine bilateral cervical thymectomy (BCT) is still discussed, although controversially.

METHODS

From a prospective database of patients who underwent parathyroid surgery for rHPT between 1975 and 2009, patients with routine BCT at initial PTX were further analyzed regarding the frequency of ectopic and supernumerary IPGs. Duration of hemodialysis and stage of chronic kidney disease were correlated with the frequency of supernumerary IPGs to elucidate a potential role of long-standing proliferation stimuli to any surplus parathyroid tissue.

RESULTS

Initial parathyroidectomy with BCT was performed in 461 patients. IPGs were resected in 205 of them (44.5%). They were ectopic in 181 (39.3%) and supernumerary in 30 patients (6.5%). The frequency of supernumerary IPGs in patients on permanent hemodialysis was 7.4% (29/392), 3.9% (1/26) in predialysis patients, and 0% (0/43) in patients after successful kidney transplantation. This differences reached no statistical significance.

CONCLUSIONS

BCT is essential in patients with fewer than four parathyroid glands identified at typical positions. Because of the low frequency of supernumerary IPGs and a suspected low proliferation stimulus, the relevance of BCT after resection of four glands in predialysis patients and those after successful kidney transplantation must be questioned. Nevertheless, routine BCT seems to be acceptable and can be recommended in patients on permanent hemodialysis not awaiting kidney transplantation until proven otherwise by prospective trials.

Parathyroid gland anatomical distribution and relation to anthropometric and demographic parameters: a cadaveric study

Parathyroid glands play an important role in controlling calcium levels, which influence muscular contraction and neurotransmission. The number of variants, localization and ectopic positions make these glands tricky during surgical exploration. Detailed anatomical knowledge of these glands is fundamental to avoid postsurgical hypoparathyroidism, such as failures during thyroidectomy and parathyroid procedures. The purposes of this work were to study and report practical knowledge for surgeons in order to localize the glands. Dissections were performed on 56 cadavers. Gland identity was confirmed by histological study. Also, mediastinal tissue and the carotid sheath were treated with Carnoy's solution to identify ectopic glands. The thyroid gland was divided and sliced to identify parathyroid glands in the parenchymal and subcapsular space. Four or more parathyroid glands were found in 89.3% of the studied specimens. Mean gland weight was 33.1 mg, and its mean measurements were 6.7 × 3.9 × 2.0 mm. In more than 90% of the cases there was a correlation with the inferior laryngeal nerve and the parathyroid glands: the upper glands were located in medial positions, and the lower ones were found to be located laterally. In 42.8% of cases at least one ectopic gland was observed. The main ectopic regions were the mediastinum and thymus (19.6%), thyroid subcapsular space (12.5%) and thyroid parenchyma (5.4%). Quantity, gland characteristics and location were not influenced by anthropometric and demographic parameters. Here we show the high incidence of parathyroid glands positioned at "abnormal" locations, and as a controversial topic in endocrine surgery, this matter must be continuously studied and reported in the literature.

Anatomy of thyroid and parathyroid glands and neurovascular relations

Historically, thyroid surgery has been fraught with complications. Injury to the recurrent laryngeal nerve, superior laryngeal nerve, or the parathyroid glands may result in profound life-long consequences for the patient. To minimize the morbidity of the operation, a surgeon must have an in-depth understanding of the anatomy of the thyroid and parathyroid glands and be able to apply this information to perform a safe and effective operation. This article will review the pertinent anatomy and embryology of the thyroid and parathyroid glands and the critical structures that lie in their proximity. This information should aid the surgeon in appropriate identification and preservation of the function of these structures and to avoid the pitfalls of the operation.

Rapid intraoperative parathyroid hormone assay in the surgical management of hyperparathyroidism

CONTEXT

Historically, successful surgical management of primary hyperparathyroidism has required bilateral exploration of the neck. By confirming complete removal of hypersecreting tissue, an intraoperative parathyroid hormone (IO-PTH) assay allows use of a more limited procedure.

OBJECTIVE

Our objective was to evaluate the utility of IO-PTH assay used in 32 parathyroid explorations versus conventional bilateral exploration used before the advent of IO-PTH assays.

METHODS

Minimally invasive parathyroidectomy (MIP) was used. Plasma samples were obtained at several intervals and were analyzed for IO-PTH by use of a rapid immunochemiluminescent assay (ICMA). Outcomes were assessed by univariate inferential testing, yielding one-tailed t-test results.

RESULTS

The study group had a mean plasma IO-PTH level decrease of 87% at ten minutes after excision. All 32 patients who underwent MIP using IO-PTH monitoring had successful surgery. At last postoperative follow-up examination, all 32 patients were normocalcemic. There were statistically significant decreases in duration of surgery, length of hospital stay, and surgery cost.

CONCLUSIONS

IO-PTH levels predicted the postoperative outcome for all patients studied, can provide valuable information to surgeons, and can decrease the duration of surgery and hospital stay.

Limitations of Tc99m-MIBI-SPECT imaging scans in persistent primary hyperparathyroidism

Background

In primary hyperparathyroidism (PHPT) the predictive value of technetium 99m sestamibi single emission computed tomography (Tc99m-MIBI-SPECT) for localizing pathological parathyroid glands before a first parathyroidectomy (PTx) is 83–100%. Data are scarce in patients undergoing reoperative parathyroidectomy for persistent hyperparathyroidism. The aim of the present study was to determine the value of Tc99m-MIBI-SPECT in localizing residual hyperactive parathyroid tissue in patients with persistent primary hyperparathyroidism (PHPT) after initial excision of one or more pathological glands.

Method

We retrospectively evaluated the localizing accuracy of Tc99m-MIBI-SPECT scans in 19 consecutive patients with persistent PHPT who had a scan before reoperative parathyroidectomy. We used as controls 23 patients with sporadic PHPT who had a scan before initial surgery.

Results

In patients with persistent PHPT, Tc99m-MIBI-SPECT accurately localized a pathological parathyroid gland in 33% of cases before reoperative parathyroidectomy, compared to 61% before first PTx for sporadic PHPT. The Tc99m-MIBI-SPECT scan accurately localized intra-thyroidal glands in 2 of 7 cases and a mediastinal gland in 1 of 3 cases either before initial or reoperative parathyroidectomy.

Conclusions

Our data suggest that the accuracy of Tc99m-MIBI-SPECT in localizing residual hyperactive glands is significantly lower before reoperative parathyroidectomy for persistent PHPT than before initial surgery for sporadic PHPT. These findings should be taken in consideration in the preoperative workup of patients with persistent primary hyperparathyroidism.

Techniques for parathyroid localization with ultrasound

Four-gland parathyroid exploration has been the gold standard for parathyroid surgery until recently. Emphasis is now placed on minimally invasive and focused parathyroidectomy. In conjunction with functional sestamibi scanning, ultrasonography permits accurate localization of enlarged parathyroid glands in the vast majority of patients with hyperparathyroidism. Consequently, ultrasound technology applied to parathyroid pathology facilitates directed surgical therapy and minimally invasive applications. As such, ultrasonography holds great promise as a tool that enables cost-effective and advanced patient care.

Lymph node involvement and surgical approach in parathyroid cancer

BACKGROUND

The best surgical approach to parathyroid cancer is disputed. Recommendations vary and are built on incoherent evidence. High rates of recurrence and death require an in-depth review of underlying findings.

METHODS

This retrospective study includes 11 patients with parathyroid cancer who underwent surgery with central and/or lateral neck dissection by a single surgeon between 2005 and 2010. The diagnosis was based on histopathological criteria in all patients. Patterns of lymph node and soft tissue involvement of these and formerly reported patients were analysed based on full-text review of all published cases of parathyroid cancer.

RESULTS

In this series only 1 of 11 patients (9.1%) manifested lymph node metastasis. In the literature, lymph node metastases have been reported in only 6.5% of 972 published patients, or in 32.1% of the 196 in whom lymph node involvement was assessed by the authors. They were, with few exceptions, localised in the central compartment. Recurrence in soft tissue is more frequent than in locoregional lymph nodes.

CONCLUSION

Oncological en bloc clearance of the central compartment with meticulous removal of all possibly involved soft tissues, including a systematic central lymph node resection, may improve outcomes and should be included in the routine approach to the suspicious parathyroid lesion. There is no need for a prophylactic lateral neck dissection.

Intrathyroid parathyroid adenoma: incidence and location--the case against thyroid lobectomy

OBJECTIVE

It has been taught that a missing parathyroid adenoma can be within the thyroid. Therefore, thyroid lobectomy is appropriate when an adenoma cannot be found. Unfortunately, this technique is often futile. The purpose of this study is to examine the frequency of unsuccessful thyroid lobectomy in parathyroid surgery and to look at the true incidence and location of intrathyroid parathyroid adenomas (iT-PAs).

STUDY DESIGN

A retrospective chart review of 11,163 patients undergoing parathyroid surgery identifying the location of more than 40,000 parathyroid glands.

SETTING

A tertiary care center specializing in parathyroid surgery.

SUBJECTS AND METHODS

A total of 1163 reoperations for persistent primary hyperparathyroidism (PHPT) were examined for the incidence and outcomes of thyroid lobectomy performed to find iT-PA. A second study examined 10,000 patients undergoing first-time parathyroidectomy to classify the location and incidence of iT-PA.

RESULTS

Thyroid lobectomy had been previously unsuccessfully performed in 77% cases of PHPT undergoing reoperation. Two or fewer glands were found in 82% prior to lobectomy. The adenoma was subsequently found on the lobectomy side in 64% and on the opposite side in 36%. True iT-PA occurred in only 0.7% of 10,000 primary cases. Another 1.2% were closely adherent to or partially within the thyroid substance. The most common location was the lower lateral quadrant of the thyroid.

CONCLUSION

The incidence of true iT-PA is less than 1%, occurring in predictable locations. Thyroid lobectomy for a missing parathyroid adenoma is typically unsuccessful and should only rarely, if ever, be performed.

[Ectopic parathyroid adenoma: Scintigraphic detection and radioguided surgery]

AIM

The aim of this study was to evaluate the role of (99m)Tc-MIBI parathyroid scintigraphy and radioguided parathyroidectomy on the diagnosis and treatment of primary hyperparathyroidism (PHP) due to ectopic adenomas.

METHODS

We reviewed 105 consecutive patients who underwent radioguided parathyroidectomy due to adenomas between March 2004 and December 2008. Of this group we studied 20 patients (19%) with ectopic adenomas. All patients had biochemical evidence of PHP, a positive parathyroid scintigraphy, radioguided detection with histolopathological confirmation of adenoma and at least 1 year-follow up. The parathyroid scintigraphy consisted on dual-phase planar and tomographic images (SPECT or SPECT/CT). During the parathyroidectomy, intraoperative PTH determinations (0, 7, 15 and 30 min after the parathyroidectomy) were done. The follow up consisted on blood examinations of PTH, calcium, phosphorus and vitamin D and assessment of renal function.

RESULTS

Parathyroid scintigraphy detected all adenomas. Scintigraphic and surgical findings were coincident in 18 cases (90%). The final adenoma localization was paraesophagic in 9 patients, cervicothymic in 5, posterior cervicomediastinal in 4, anterior mediastinal in 1 and parathymic in 1. The parathyroidectomy consisted on 12 minimally invasive surgeries, 2 unilateral cervicotomies, 4 bilateral cervicotomies and 2 sternotomies. No case of persistent or recurrent PHP was observed during the follow up.

CONCLUSIONS

Parathyroid scintigraphy (SPECT/CT) and radioguided surgery are effective methods on the localization and treatment of PHP due to ectopic adenomas. In our study the radioguided parathyroidectomy was successful in all cases and there was no evidence of persistent or recurrent hyperparathyroidism on the follow up.

Thymus-associated parathyroid hormone has two cellular origins with distinct endocrine and immunological functions

In mammals, parathyroid hormone (PTH) is a key regulator of extracellular calcium and inorganic phosphorus homeostasis. Although the parathyroid glands were thought to be the only source of PTH, extra-parathyroid PTH production in the thymus, which shares a common origin with parathyroids during organogenesis, has been proposed to provide an auxiliary source of PTH, resulting in a higher than expected survival rate for aparathyroid Gcm2^−/− mutants. However, the developmental ontogeny and cellular identity of these “thymic” PTH–expressing cells is unknown. We found that the lethality of aparathyroid Gcm2^−/− mutants was affected by genetic background without relation to serum PTH levels, suggesting a need to reconsider the physiological function of thymic PTH. We identified two sources of extra-parathyroid PTH in wild-type mice. Incomplete separation of the parathyroid and thymus organs during organogenesis resulted in misplaced, isolated parathyroid cells that were often attached to the thymus; this was the major source of thymic PTH in normal mice. Analysis of thymus and parathyroid organogenesis in human embryos showed a broadly similar result, indicating that these results may provide insight into human parathyroid development. In addition, medullary thymic epithelial cells (mTECs) express PTH in a Gcm2-independent manner that requires TEC differentiation and is consistent with expression as a self-antigen for negative selection. Genetic or surgical removal of the thymus indicated that thymus-derived PTH in Gcm2^−/− mutants did not provide auxiliary endocrine function. Our data show conclusively that the thymus does not serve as an auxiliary source of either serum PTH or parathyroid function. We further show that the normal process of parathyroid organogenesis in both mice and humans leads to the generation of multiple small parathyroid clusters in addition to the main parathyroid glands, that are the likely source of physiologically relevant “thymic PTH.”

Due to the important role of PTH in the regulation of physiological activities, disorders in PTH production can cause many diseases in humans. Thus it is very important to understand where PTH is produced and how it is regulated. Many people have been found to have ectopic and supernumerary parathyroid glands without clear ontogenesis. In addition, the thymus, which develops together with the parathyroid during embryogenesis, has been proposed to be an auxiliary source of PTH with endocrine function; however, PTH is also a tissue-restricted self-antigen expressed by the thymus. In this paper, we provide insights into the ontogeny and function of thymus-associated PTH. We found that ectopic and supernumerary parathyroid glands originate from the normal developmental process underlying the separation of parathyroid and thymus, resulting in misplaced parathyroids close or attached to thymus. In the thymus, thymic epithelial cells can produce a low level of PTH via a different mechanism than the parathyroid and provide functional data that TEC-derived PTH does not have endocrine function. In summary, our data show that the thymic source of PTH has no endocrine function and, instead, has an expression pattern in the thymus consistent with that of a self-antigen for negative selection.

Is thymectomy worthwhile in central lymph node dissection for differentiated thyroid cancer?

BACKGROUND

Clinical guidelines edited in 2006 by the American Thyroid Association (ATA) and stated in the European Thyroid Association Consensus (ETA) recommend routine central lymph node dissection (level VI neck dissection) in addition to thyroidectomy for the surgical treatment of differentiated thyroid cancer. This central dissection increases the incidence of postoperative hypocalcemia, which is related to the resection or devascularization of the inferior parathyroids together with bilateral thymectomy. Some authors perform unilateral thymectomy in order to minimize this complication. Our aim was to study the benefit/risk (incidence of thymic lymph node metastases versus postoperative hypocalcemia) of both procedures.

METHODS

We retrospectively reviewed the records of 138 patients who underwent total thyroidectomy with central neck lymph node dissection for differentiated thyroid cancer between 2004 and 2007. Bilateral thymectomy was performed in 45 patients (group 1, 15 males and 30 females) and unilateral thymectomy was performed in 93 patients (group 2, 27 males and 66 females). Forty-two papillary and 3 medullary cancers were found in group 1, and 75 papillary, 2 follicular, and 17 medullary cancers were found in group 2. The presence of thymic metastases at pathology and the occurrence of postoperative hypocalcemia were reviewed.

RESULTS

Two cases of papillary thymic metastases were found in group 1. These were lymph node micrometastases localized in the ipsilateral side of the primary tumor in both cases. Transient hypocalcemia was significantly more frequent (P < 0.001) in group 1 than in group 2: 16 patients (35.5%) versus 10 (10.7%). There was one case of permanent hypocalcemia in group 1 after the follow-up period.

CONCLUSIONS

Bilateral thymectomy risk outweighs any likely carcinologic benefit. We do not recommend routine bilateral thymectomy during central neck dissection for differentiated thyroid cancer.

Contact endoscopy for identifying the parathyroid glands during thyroidectomy

Aim of this study was to analyse contact endoscopy as an auxiliary method for identifying parathyroid glands during thyroid surgery and to identify other variables that may interfere with this correlation. Overall, 125 patients underwent thyroid surgery between January 2004 and February 2006. The variables analysed were: the total duration of surgery; time taken to locate and identify parathyroid glands; improvement in identifying these; numbers of parathyroid glands located by the surgeon and confirmed by contact endoscopy; histopathological diagnosis; presence of thyroiditis; thyroid weight; number of parathyroid glands left in thyroid specimens; and number of parathyroid gland autotransplantations. A total of 331 parathyroid glands were observed by the surgeon. However, 282 glands were identified by contact endoscopy. Nine parathyroid glands (7.2%) were observed together with thyroid specimens (Kappa = 0.534). The longer the total duration of surgery (p = 0.03) and time taken to locate and identify (p = 0.00) the parathyroid glands by contact endoscopy, the lower the observed agreement. The second year of performing contact endoscopy led to better agreement between the results (p = 0.02). In conclusion, contact endoscopy is an efficient auxiliary method for identifying parathyroid glands during thyroid surgery. During the period studied, association between total duration of surgery and time taken to locate and identify parathyroid glands was statistically significant.

A novel nomenclature to classify parathyroid adenomas

BACKGROUND

A uniform and reliable description of the exact locations of adenomatous parathyroid glands is necessary for accurate communications between surgeons and other specialists. We developed a nomenclature that provides a precise means of communicating the most frequently encountered parathyroid adenoma locations.

METHODS

This classification scheme is based on the anatomic detail provided by imaging and can be used in radiology reports, operative records, and pathology reports. It is based on quadrants and anterior-posterior depth relative to the course of the recurrent laryngeal nerve and the thyroid parenchyma. The system uses the letters A-G to describe exact gland locations.

RESULTS

A type A parathyroid gland is a gland that originates from a superior pedicle, lateral to the recurrent laryngeal nerve compressed within the capsule of the thyroid parenchyma. A type B gland is a superior gland that has fallen posteriorly into the tracheoesophageal groove and is in the same cross-sectional plane as the superior portion of the thyroid parenchyma. A type C gland is a gland that has fallen posteriorly into the tracheoesophageal groove and on a cross-sectional view lies at the level of or below the inferior pole of the thyroid gland. A type D gland lies in the midregion of the posterior surface of the thyroid parenchyma, near the junction of the recurrent laryngeal nerve and the inferior thyroid artery or middle thyroidal vein; because of this location, dissection is difficult. A type E gland is an inferior gland close to the inferior pole of the thyroid parenchyma, lying in the lateral plane with the thyroid parenchyma and anterior half of the trachea. A type F gland is an inferior gland that has descended (fallen) into the thyrothymic ligament or superior thymus; it may appear to be "ectopic" or within the superior mediastinum. An anterior-posterior view shows the type F gland to be anterior to the trachea. A type G gland is a rare, truly intrathyroidal parathyroid gland.

CONCLUSIONS

A reproducible nomenclature can provide a means of consistent communication about parathyroid adenoma location. If uniformly adopted, it has the potential to reliably communicate exact gland location without lengthy descriptions. This system may be beneficial for surgical planning as well as operative and pathology reporting.

Endoscopic total parathyroidectomy and partial parathyroid tissue autotransplantation for patients with secondary hyperparathyroidism: a new surgical approach

Background

Secondary hyperparathyroidism (SHPT) (i.e., renal hyperparathyroidism) is one of the most serious complications in long-term hemodialysis patients. The purpose of this retrospective study was to explore the feasibility of a new surgical approach—endoscopic total parathyroidectomy with autotransplantation (ETP+AT)—and evaluate its practical application for patients with SHPT.

Methods

The study included 34 SHPT patients who underwent ETP+AT from among 67 cases at the Department of Minimally Invasive Surgery, the First Affiliated Hospital of Nanjing Medical University over a 3-year period. The other 33 patients underwent traditional total parathyroidectomy with autotransplantation (TP+AT). Two criteria were used as indications to perform ETP+AT in SHPT patients. The first was a high serum parathyroid hormone level (PTH >800 pg/ml) associated with hypercalcemia and/or hyperphosphatemia that which were refractory to medical treatment. The second criterion was the presence of clinical symptoms including pruritus, bone and joint pain, muscle weakness, progression of soft tissue calcification, and spontaneous fractures. Ultrasonography, ^99mTc sestamibi scans, and computed tomography were used to evaluate the thyroid and parathyroid glands.

Results

There was no surgery-related mortality among any of the patients with ETP+AT. One patient underwent conventional neck exploration because of bleeding and injury of a unilateral recurrent laryngeal nerve after the operation. Preoperative symptoms were alleviated, and the serum PTH and alkaline phosphatase levels, hyperphosphatemia, and hypercalcemia were improved or normalized in most patients. Recurrence was observed in one patient with a sixth parathyroid gland behind his thyroid, and the patient required a second operation. Hypoparathyroidism was not found after the operation. The clinical data were compared between ETP+AT and TP+AT.

Conclusions

ETP+AT is a safe option for the treatment of SHPT with low morbidity and mortality, shorter hospital stay and low recurrence rate. It is important to avoid intraoperative bleeding, identify all parathyroid glands during the surgery, and choose adequate parathyroid tissues for autografting.

The fallen one: the inferior parathyroid gland that descends into the mediastinum

BACKGROUND

Inferior parathyroid glands are located along the embryologic migration path of the thymus and can rest in the thyrothymic ligament or anterior mediastinum. Our nomenclature system designates these glands as "fallen" (type F) glands. This study reviews our experience with type F parathyroid glands to determine which can be retrieved successfully through a cervical incision.

STUDY DESIGN

A retrospective review of patients who underwent parathyroidectomy between June 1998 and May 2008 was performed. Patient demographics, localization studies, and operative and pathologic reports were analyzed. Distance from the superior aspect of the clavicle to the target parathyroid gland was measured.

RESULTS

Sixty (9.2%) patients had a type F parathyroid gland. Parathyroidectomy was performed through cervical incision in 54 (90%) patients and 6 (10%) required a thoracic approach. Preoperative imaging identified parathyroid glands located >or=6 cm below the superior aspect of the clavicle in eight patients. Of these, six (75%) required a thoracic approach and two (25%) were resected through a cervical incision with concomitant thymectomy. Parathyroidectomy was successfully performed through a cervical incision in all 52 (100%) patients in whom the target parathyroid gland was <6 cm below the superior aspect of the clavicle (Fisher's exact test, p < 0.001).

CONCLUSIONS

A cervical approach allows successful retrieval of type F parathyroid glands located <6 cm below the superior aspect of the head of the clavicle in the anterior mediastinum. Parathyroidectomy for glands located >or=6 cm below the superior aspect of the clavicle can be attempted from the neck with concomitant thymectomy, but the majority will require a thoracic approach.

Long-term treatment with cinacalcet and conventional therapy reduces parathyroid hyperplasia in severe secondary hyperparathyroidism

BACKGROUND

The effect of cinacalcet on the structural pattern of hyperplastic parathyroid glands was evaluated, using high-resolution colour Doppler (CD) sonography, in haemodialysis patients with severe, inadequately controlled, secondary hyperparathyroidism (sHPT).

METHODS

Nine patients (6 males, 3 females; mean age +/- SD, 55.5 +/- 12.6 years) received cinacalcet, with adaptation of existing concomitant therapies. Biochemical parameters and the morphology and vascular pattern of hyperplastic parathyroid glands were measured at baseline and every 6 months thereafter, for a follow-up period of 24-30 months.

RESULTS

At baseline, 28 hyperplastic glands were identified. Cinacalcet led to a reduction in glandular volume during the course of the study: 68% in glands with a baseline volume <500 mm(3) and 54% in glands with a baseline volume >or=500 mm(3). The mean volume +/- SD of glands <500 mm(3) changed significantly from the baseline (233 +/- 115 mm(3)) to the end of follow-up (102 +/- 132 mm(3), P = 0.007). Levels of mean serum phosphorus, calcium and calcium-phosphorus product decreased, but not significantly, whereas there were significant decreases in mean parathyroid hormone +/- SD levels (1196 +/- 381 pg/ml versus 256 +/- 160 pg/ml; P < 0.0001) and alkaline phosphatase +/- SD levels (428 +/- 294 versus 223 +/- 88 IU/l; P = 0.04), accompanied by an improvement in a subjective clinical score.

CONCLUSIONS

Cinacalcet, in combination with conventional treatments, led to an improvement in biochemical and clinical parameters of sHPT and reduced glandular volume in patients with severe sHPT. Volume reduction was more evident in smaller glands. Longer term, larger, randomized clinical trials are needed to confirm these preliminary findings and to further define a more systematic approach in the treatment of sHPT.

Incidence of parathyroid glands located in thymus in patients with renal hyperparathyroidism

BACKGROUND

Parathyroid glands are frequently located in thymus, and it is essential to resect thymic tissue from the neck incision, especially in surgery for renal hyperparathyroidism (HPT).

METHODS

In this study, we evaluated the incidence, location, and type of intrathymic parathyroid glands in 902 patients who underwent initial parathyroidectomy (PTx) for advanced renal HPT in our department. Removal of the thymic tongues on both sides was routinely performed from the neck incision, and the thymic tissue was carefully examined both macroscopically and microscopically.

RESULTS

Of the 902 patients in the study, 269 had only inferior parathyroid glands in the thymus, in 62 patients only supernumerary glands were found in the thymic tongue, and in 78 patients both inferior and supernumerary glands were present in thymic tissue. Therefore the incidence of patients with intrathymic glands was 45.3% (269 + 62 + 78 = 409/902). In 129 (92.1%) of 140 patients with supernumerary glands in the thymic tongue, these glands were detected only on histopathological examination, and about half of them were classified as the parathyromatosis type.

CONCLUSIONS

In the human, parathyroid glands might be located in the thymus in about 50%. If the inferior gland/glands cannot be found around the inferior pole of thyroid lobe, it is very important to search for glands in the thymic tongue. Moreover, to avoid missing supernumerary glands, removal of the thymic tongue on both sides is essential in surgery for renal HPT.