The anatomic basis of parathyroid surgery

Supernumerary ectopic parathyroid adenoma in the aortopulmonary window: Navigating diagnostic and surgical challenges

INTRODUCTION

Primary hyperparathyroidism (PHPT) is the most common cause of hypercalcemia and has shifted from a rare condition to a common endocrine disorder. Advances in diagnostic methods have led to more incidental diagnoses, particularly in asymptomatic patients. Ectopic parathyroid adenomas are a rare cause of PHPT, with the vast majority of cases involving parathyroid glands in typical anatomical locations. However, the occurrence of a fifth parathyroid adenoma is exceptionally uncommon, especially when located in an ectopic position.

CASE PRESENTATION

We report an uncommon case of primary hyperparathyroidism in a 60-year-old male with longstanding hypercalcemia attributed to a fifth ectopic parathyroid adenoma localized in the aortopulmonary window. Initial imaging modalities failed to localize the adenoma, which was detected by 4D-CT but not on SPECT/CT, and remission was achieved through surgical resection, with intraoperative PTH monitoring confirming total resection.

DISCUSSION

Delayed diagnosis of ectopic parathyroid adenomas can lead to complications, as in our patient with nephrolithiasis and hypercalcemia. Advanced imaging techniques like 4D-CT are crucial when conventional methods fail. Embryological anomalies can result in ectopic or supernumerary parathyroid glands, complicating localization. Intraoperative PTH monitoring ensures complete resection and lowers reoperation rates.

CONCLUSION

This case highlights the challenges of diagnosing ectopic parathyroid adenomas and the importance of considering rare ectopic adenomas in patients with PHPT, particularly when standard imaging doesn't yield conclusive results. We also discuss the role of advanced imaging modalities and intraoperative PTH monitoring in guiding surgical decisions and determining the appropriate point to conclude the procedure, ensuring successful outcomes.

Clinical significance and risk factors of incidental parathyroidectomy after total thyroidectomy

PURPOSE

Postoperative hypoparathyroidism is the most common complication after total thyroidectomy(TT). The clinical significance of incidental parathyroid glands(IP) detected in pathological examination of removed surgical material is still controversial. The aim of this study was to evaluate the clinical follow-up findings and risk factors of patients with IP.

METHODS

Postoperative pathology results and postoperative biochemical findings of patients who underwent TT±Central Neck Dissection(CND)/Lateral Neck Dissection(LND) between September,2020 and September,2023 in single institution were retrospectively evaluated. Patients with IP were divided into Group-1, and patients without IP were divided into Group-2. Patients of Group-1 were divided as Single IP and Double IP subgroups according to the number of IP.

RESULTS

The findings of a total of 412 patients were evaluated. IP was detected in 90(21.8%) of the patients. Postoperative hypoparathyroidism was more common in Group-1 at the 6th hour, 24th hour and 1st month postoperatively (69.7% vs. 31.7%, p < 0.0001; 61.1% vs. 27.7%, p < 0.0001, 26.2% vs. 12.2%, p = 0.002, respectively). Persistent hypoparathyroidism was observed at a rate of 5.3% in Group-2 and 11.5% in Group-1 (p = 0.041). Postoperative hypocalcemia was seen more frequently in Group-1 than in Group-2 at the 12th hour (34.4% vs. 23.2%, p = 0.031, respectively). There was no difference between Single IP vs. Double IP groups for the serum levels of Calcium and PTH. Among the risk factors evaluated for the detection of IP, in the univariance analysis, operation indications(p = 0.018), CND(p < 0.0001), surgeon experience(p = 0.016), thyroid gland volume(p = 0.02), preoperative serum TSH value(p = 0.031); in multivariance analysis, operation type ( ± CND) (OR:2.785; 95% CI: 1.175-6.605; p = 0.020) and operator experience between 10-20 years (OR: 0.117, 95% CI: 0.033-0.418, p = 0.001) and >20 years (OR: 0.254, 95%CI: 0.085-0.760, p = 0.014) were found significant compared to operators experienced <5 years.

CONCLUSION

Patients with detected IP after total thyroidectomy have lower postoperative Calcium and PTH. Significant risk factors for the IP were low level of surgeon experience and undergoing CND.

Beyond the Thyroid Bed: A Rare Case of Vagal Parathyroid Adenoma Causing Primary Hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a significant endocrine disorder characterized by excessive secretion of parathyroid hormone (PTH), leading to hypercalcemia. It is intriguing how the majority of cases are attributed to solitary hyperfunctioning parathyroid adenomas, while a smaller fraction involves multiglandular disease or rarely parathyroid carcinoma. Ectopic parathyroid adenomas, though less common, pose a considerable challenge in diagnosis and surgical management due to their aberrant location. It is crucial to consider the possibility of multiglandular disease or ectopic glands when preoperative localization fails or when repeat surgery is necessary. Moreover, the mention of intravagal parathyroid adenomas emphasizes the need for vigilance in considering rare ectopic locations during both diagnosis and surgical intervention. These cases underscore the importance of continuous advancements in imaging modalities such as four-dimensional computed tomography scans or 18 F Choline Pet CT to enhance localization and visualization, ultimately improving surgical outcomes. Overall, these clinical vignettes shed light on the diverse presentations and challenges in managing PHPT, emphasizing the importance of a multidisciplinary approach integrating clinical, radiological, and surgical expertise to optimize patient care. We describe a patient with persistent primary hyperparathyroidism who underwent one unsuccessful surgical procedure due to an intravagal parathyroid adenoma.

Parathyroid vascular anatomy using intraoperative mapping angiography: the PARATLAS study

BACKGROUND

Understanding vascular anatomy of the parathyroid glands (PG) is crucial during thyroidectomy. The aim of this study was to describe patterns and distribution of parathyroid vessels.

METHOD

An analysis of all intraoperative mapping angiographies from indocyanine green injection and fluorescence imaging in patients undergoing thyroid surgery between February 2020 and September 2021. The parathyroid vessels were classified according to the pattern of contact with the thyroid. Data collection and analysis were carried out in accordance with MR004 reference methodology.

RESULTS

A total of 200 angiographies from 196 patients were analysed (159 female/37 male, mean(s.d.) age: 54.2 ± 13.7 years), and 320 PGs were assessed. The parathyroid vessels had no contact with the thyroid in 20 (6%; Type 0), a single-point of contact in 74 (23%; Type 1), a posterior path in 47 (15%; Type 2), a lateral path in 68 (21%; Type 3), an intrathyroidal path in 19 (6%; Type 4), and a possible medial path in 26 (8%; Type X1) cases. The course of the vessels was unclear in 36 cases (11%; Type X2). Spatial distribution analysis showed a concentration of superior parathyroid vessels around Zuckerkandl's tubercle, whereas the distribution of the inferior parathyroid vessels was anterior and sparse.

CONCLUSION

Intraoperative mapping angiographies help to define the main patterns of the parathyroid vessels according to their contact with the thyroid and provide surgically useful information about spatial vessel distribution.

Chapter 0: Introduction to the consensus on primary hyperparathyroidism from the French Society of Endocrinology, French speaking Association of Endocrine Surgery and French Society of Nuclear Medicine

This consensus on primary hyperparathyroidism, drawn up under the aegises of the French Society of Endocrinology (SFE), French speaking Association of Endocrine Surgery (AFCE) and French Society of Nuclear Medicine (SFMN), provides an update on positive, etiological and differential diagnosis and treatment in primary hyperparathyroidism. These recommendations take account of recent increase in the prevalence of primary hyperparathyroidism, due to 1. More systematic routine measurement of blood calcium and improved quality of parathyroid hormone assays, 2. Developments in genetics, 3. The steady increase in life expectancy, affecting the long-term consequences of asymptomatic hyperparathyroidism, 4. Advances in parathyroid imaging, 5. Targeted surgical management, 6. Therapeutic alternatives when surgery is contraindicated, and 7. Better understanding of pathophysiological mechanisms and hence of differential diagnoses, and in particular secondary and tertiary hyperparathyroidism. The consensus is published in French on the Société Française d'Endocrinologie website (https://www.sfendocrino.org/), and in English in the Annales d'Endocrinologie/Annals of Endocrinology and the Journal of Visceral Surgery. A summary for general practitioners will be made available on the French Health Authority (HAS) website (https://www.has-sante.fr/).

The polar vessel sign: insights from CT imaging analysis in Asian Indian primary hyperparathyroidism

PURPOSE

Data on the polar vessel sign (enlarged feeding vessel terminating in parathyroid lesions) on four-dimensional computed tomography (4D-CT) is limited. We performed a retrospective analysis to determine the prevalence, predictors, and adjunctive utility of polar vessel sign in pre-operative 4D-CT of patients with primary hyperparathyroidism (PHPT).

METHODS

One radiologist blinded to the patients' details reported the 4D-CT of eighty-four operated patients with histopathology-proven single-gland PHPT. Two protocols were used to obtain arterial-phase images: timed via bolus tracking (n = 41) or fixed at 20 s after contrast injection (n = 43).

RESULTS

Seventy-one patients were symptomatic for PHPT, with median serum calcium 12.1 mg/dL. On the arterial phase of 4D-CT, 88.1% of lesions had the polar vessel sign, including 7/9 asymptomatic patients, 6/6 parathyroid carcinomas, and 3/4 ectopic(1:mediastinum, 2:thyro-thymic ligament). Predictors of polar vessel sign were maximum lesion dimension (2.2 vs. 1.4 cm; P = 0.03), solid-cystic CT morphology (47.3% vs. none; P = 0.004), and bolus tracking-timed arterial phase (55.4% vs. none; P = 0.001). Of these, bolus tracking improved the polar vessel's visualization (100% vs. 76.7%; P = 0.001) independent of lesion dimension and solid-cystic morphology. The latter two predicted polar vessel sign in images obtained at a fixed interval (20 s). A significantly lower proportion of bolus tracking-timed scans had lesion percentage arterial enhancement (PAE) < 128.9% (2/41 vs. 9/43; P = 0.04). Even with suboptimal PAE, the polar vessel helped identify 9/11 lesions.

CONCLUSION

The polar vessel sign demonstrated an additive role to PAE during CT reporting. Bolus tracking is valuable in optimizing vessel and tumor arterial enhancement and is easily incorporated into parathyroid 4D-CT protocol.

Characterisation of Kürsteiner canals of parathyroid: imparting relevance to a one-and-a-quarter-century-old concept

AIMS

Kürsteiner canals (KC) were described at least 125 years ago as pharyngeal pouch embryological remnants of parathyroid and thymic development. While considered precursors for a subset of parathyroid cysts and salivary heterotopias (SH), they remain enigmatic. We now define a comprehensive phenotype of KC remnants and investigate their role in a spectrum of parathyroid lesions.

METHODS AND RESULTS

`Sixty-two cystic and 22 non-cystic parathyroid lesions (73 patients) were retrieved from our institutional archive (2011-23) and evaluated for the presence of KC and prevalence of KC phenotype in parathyroid hormone (PTH)-positive and PTH-negative cysts. KC phenotype was defined as: cysts and tubules with surrounding sclerosis; bland, unilayered lining with frequent nuclear indentation of lumina; vesicular chromatin relative to chief cells; attenuated eosinophilic to 'hyper-cleared' cytoplasm; and staining pattern PTH-negative, SOX-10-positive, CK7-positive, GATA-3-positive and PAX-9 dim, a subset with oestrogen/progesterone receptor (ER/PR) positivity. Thirty PTH-negative cysts were identified in the neck/mediastinum; 14 of this group also showed SH. Thirty-two PTH-positive cysts included: 11 cystic parathyroid adenomas, 17 hyperplastic parathyroids, and four carcinomas. KC showed two distinct subtypes and were often found near PTH-negative cysts. PTH-negative cysts were associated with inferior parathyroids, SOX-10 positivity, fibrosclerosis, vesicular nuclei indenting cyst lumina and hyper-cleared or attenuated eosinophilic cytoplasm.

CONCLUSIONS

KC are common in parathyroids and show a distinct histological and immunohistochemical profile, with an inferior predilection favouring branchial cleft III distribution. Diagnostically, the high prevalence of this phenotype in PTH-negative cysts and salivary heterotopia supports derivation of non-functioning cysts from KC. Conversely, PTH-positive cysts are more compatible with cystic change within hyperfunctioning glands.

Management of Type III Intrathyroidal Parathyroid Adenomas By Enucleation: Case Report and Literature Review

Parathyroid adenoma is a common endocrine disorder, but its intrathyroid presentation is relatively rare. The traditional approach, such as thyroid blind lobectomy, is the most frequent modality of treatment due to the possible unclear localization of the adenoma in the preoperative workup. This increases the risk of unnecessary probability of hypothyroidism.  We report a case of a 48-year-old male patient who was referred to the endocrinology outpatient clinic due to elevated calcium (Ca) and elevated parathyroid hormone (PTH) levels, indicating primary hyperparathyroidism (PHPT). Thyroid ultrasound (US) confirmed the presence of thyroid lobe nodule and the fine needle aspiration cytology (FNAC) revealed the presence of parathyroid cells. A thyroid scan with the single photon emission computed tomography (SPECT)/CT revealed a possible left inferior parathyroid adenoma. The patient underwent surgical excision of the left parathyroid adenoma by cervicotomy and thyroid lobe preservation with prompt normal PTH level recovery without complications. One year follow-up revealed no complications, and the patient's serum thyroid function, PTH, and Ca levels remained within the normal range. The management of type III intrathyroidal parathyroid adenomas (iT-PAs) by enucleation offers a viable alternative for selected PHPT patients. Advanced diagnostic imaging helps but is often not able to confirm exactly their location. Individualized surgical approaches contribute to successful outcomes while preserving thyroid tissue. The establishment of standardized guidelines is essential to optimize the management of iT-PAs and enhance patient care. We present a case of a type III iT-PA by enucleation preserving the thyroid tissues along with the analysis of the few cases previously reported.

Ultrasonographic features of normal parathyroid glands confirmed during thyroid surgery in adult patients

PURPOSE

This study was performed to examine the ultrasonography (US) features of normal parathyroid glands (PTGs) that were identified on preoperative US and subsequently confirmed during thyroid surgery.

METHODS

This retrospective study included a consecutive sample of 161 patients (mean±standard deviation age, 56±14 years; 128 women) with 294 normal PTGs identified on preoperative US PTG mapping and confirmed during thyroidectomy. A presumed normal PTG on US was defined as a small, round to oval, hyperechoic structure in the central neck. These presumed normal PTGs, as identified on preoperative US, were mapped onto thyroid computed tomography images and diagrams of the thyroid gland and neck. During the preoperative real-time US examinations, the location, size, shape, echogenicity, echotexture, and intraglandular vascular flow of the identified presumed PTGs were assessed. These characteristics were compared between superior and inferior PTGs using the generalized estimating equation method.

RESULTS

The typical US features of homogeneous hyperechogenicity without intraglandular vascular flow were observed in 267 (90.8%) normal PTGs, while atypical features, including isoechogenicity (1.0%), heterogeneous echotexture with focal hypoechogenicity (5.8%), and intraglandular vascular flow (3.7%), were noted in 27 (9.2%). Inferior PTGs were more frequently identified in posterolateral (36.1% vs. 5.3%) and thyroid pole locations (29.9% vs. 5.3%), and less frequently in posteromedial locations (29.2% vs. 88.0%), compared to superior PTGs (P<0.001 for each comparison).

CONCLUSION

Most normal PTGs displayed the typical US features of homogeneous hyperechogenicity without intraglandular vascular flow. However, in rare cases, normal PTGs exhibited atypical features, including isoechogenicity, heterogeneous echotexture with focal hypoechogenicity, and intraglandular vascular flow.

Superior Parathyroid Masquerading as Retropharyngeal Lymph Node

Introduction

Ectopic parathyroid glands have been reported with an incidence of 2-22%. Undescended parathyroid glands, defined as glands situated above the carotid bifurcation or > 1 cm cranial to the superior pole of the thyroid gland, comprise 2-7% of all ectopic parathyroid glands. We report a case of incidentally discovered parathyroid gland located in the retropharyngeal space at the level of the oropharynx.

Case Presentation

The patient in this report was a 60-year-old female with squamous cell carcinoma of the tonsil T2N0M0 with MRI showing a hyperintense ovoid structure, medial to the carotids at the level of the oropharynx, corresponding to the location of the lateral group of retropharyngeal lymph nodes. Patient underwent transoral ultrasonic radical tonsillectomy along with a retropharyngeal lymph node dissection by the transcervical route. Postoperative histopathology revealed the retropharyngeal node sampled to be a normal parathyroid gland.

Discussion

"High" undescended parathyroid gland as reported here along with 4 other cases of infratemporal fossa parathyroid glands reported previously, can be the cause for recurrent missed adenomas. Being extracervical in location, these are likely to be missed if the skull base has not been included in the preoperative Tc-99 sestamibi scan and also during bilateral neck exploration.

Imaging Recommendations for Diagnosis and Management of Primary Parathyroid Pathologies: A Comprehensive Review

Parathyroid pathologies are suspected based on the biochemical alterations and clinical manifestations, and the predominant roles of imaging in primary hyperparathyroidism are localisation of tumour within parathyroid glands, surgical planning, and to look for any ectopic parathyroid tissue in the setting of recurrent disease. This article provides a comprehensive review of embryology and anatomical variations of parathyroid glands and their clinical relevance, surgical anatomy of parathyroid glands, differentiation between multiglandular parathyroid disease, solitary adenoma, atypical parathyroid tumour, and parathyroid carcinoma. The roles, advantages and limitations of ultrasound, four-dimensional computed tomography (4DCT), radiolabelled technetium-99 (99mTc) sestamibi or dual tracer 99mTc pertechnetate and 99mTc-sestamibi with or without single photon emission computed tomography (SPECT) or SPECT/CT, dynamic enhanced magnetic resonance imaging (4DMRI), and fluoro-choline positron emission tomography (18F-FCH PET) or [11C] Methionine (11C -MET) PET in the management of parathyroid lesions have been extensively discussed in this article. The role of fluorodeoxyglucose PET (FDG-PET) has also been elucidated in this article. Management guidelines for parathyroid carcinoma proposed by the American Society of Clinical Oncology (ASCO) have also been described. An algorithm for management of parathyroid lesions has been provided at the end to serve as a quick reference guide for radiologists, clinicians and surgeons.

Molecular imaging of thyroid and parathyroid diseases

INTRODUCTION

Molecular imaging of thyroid and parathyroid diseases has changed in recent years due to the introduction of new radiopharmaceuticals and new imaging techniques. Accordingly, we provided an clinicians-oriented overview of such techniques and their indications.

AREAS COVERED

A review of the literature was performed in the PubMed, Web of Science, and Scopus without time or language restrictions through the use of one or more fitting search criteria and terms as well as through screening of references in relevant selected papers. Literature up to and including December 2023 was included. Screening of titles/abstracts and removal of duplicates was performed and the full texts of the remaining potentially relevant articles were retrieved and reviewed.

EXPERT OPINION

Thyroid and parathyroid scintigraphy remains integral in patients with thyrotoxicosis, thyroid nodules, differentiated thyroid cancer and, respectively, hyperparathyroidism. In the last years positron-emission tomography with different tracers emerged as a more accurate alternative in evaluating indeterminate thyroid nodules [18F-fluorodeoxyglucose (FDG)], differentiated thyroid cancer [124I-iodide, 18F-tetrafluoroborate, 18F-FDG] and hyperparathyroidism [18F-fluorocholine]. Other PET tracers are useful in evaluating relapsing/advanced forms of medullary thyroid cancer (18F-FDOPA) and selecting patients with advanced follicular and medullary thyroid cancers for theranostic treatments (68Ga/177Ga-somatostatin analogues).

Real-time imaging of ipsilateral parathyroid glands by retrograde injection of methylene blue into the superior thyroid artery: a new intraoperative parathyroid protection method

BACKGROUND

Postoperative hypoparathyroidism caused by parathyroid injury is a problem faced by thyroid surgeons. The current technologies for parathyroid imaging all have some defects.

METHODS

Patients with differentiated thyroid carcinoma (DTC) who underwent unilateral thyroidectomy plus ipsilateral central lymph node dissection were recruited. We dissected the main trunk of the superior thyroid artery entering the thyroid gland and placed the venous indwelling tube into the artery. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were calculated.

RESULTS

A total of 132 patients enrolled in this single-arm clinical trial, 105 of them completed retrograde catheterization via the superior artery. The sensitivity was 69.23 and 83.33% respectively. The specificity was 72.91 and 64.89%. The accuracy was 72.91 and 64.89%. The PPV was 85.71 and 81.08%. The NPV was 22.58 and 45.45%. There were no patients with allergic reactions to the methylene blue, or methylene blue toxicity.

CONCLUSIONS

Retrograde injection of methylene blue via the superior thyroid artery is an effective and safe method to visualize parathyroid glands. This method can accurately locate the target organ by ultraselecting the blood vessel and injecting the contrast agent while avoiding background contamination and reducing the amount of contrast agent.

TRIAL REGISTRATION

Clinical trial registration numbers and date of registration: ChiCTR2300077263、02/11/2023.

The Parathyroid Gland: An Overall Review of the Hidden Organ for Radiologists

Parathyroid glands are small endocrine glands that regulate calcium metabolism by producing parathyroid hormone (PTH). These are located at the back of the thyroid gland. Typically, four glands comprise the parathyroid glands, although their numbers may vary among individuals. Parathyroid diseases are related to parathyroid gland dysfunction and can be caused by problems with the parathyroid gland itself or abnormal serum calcium levels arising from renal disease. In recent years, as comprehensive health checkups have become more common, abnormal serum calcium levels are often found incidentally in blood tests, after which several additional tests, including a PTH test, ultrasonography (US), technetium-99m sestamibi parathyroid scan, single-photon-emission CT (SPECT)/CT, four-dimensional CT (4D-CT), and PET/CT, are performed for further evaluation. However, the parathyroid gland remains an organ less familiar to radiologists. Therefore, the normal anatomy, pathophysiology, imaging, and clinical findings of the parathyroid gland and its associated diseases are discussed here.

Comparison of indocyanine green angiography vs intraoperative parathyroid hormone in early prediction of risk of post-thyroidectomy hypocalcemia: a prospective cohort study

Introduction

Indocyanine green (ICG) angiography is the 'real-time intraoperative imaging' technique used to reduce the chances of hypoparathyroidism in post-thyroidectomy patients. In our study, the authors predicted the risk of early post-thyroidectomy hypocalcemia by intraoperative evaluation of parathyroid gland perfusion by ICG angiography.

Materials and methods

In patients who underwent total thyroidectomy, ICG angiography was done using the SPY PHI imaging system (Stryker). Post-thyroid specimen removal, scoring of parathyroids was done in spy contrast mode. All 4 or <4 visualized parathyroids were scored for vascularity with the highest score of 8. Serum ionized calcium was done 6 h postsurgery and on the morning and evening of postoperative days 1 and 2. Calcium supplements were given to only those who developed clinical or severe biochemical hypocalcemia.

Results

Out of 60, postoperative hypocalcemia was noted in 41 patients. Total ICG score ≤5 was seen in 34 patients, out of which 28 developed postoperative hypocalcemia showing PPV 82.3% and diagnostic accuracy of 68.3% while iPTH (4.28 pmol/l) showed PPV 76.7 and diagnostic accuracy 70 %. In eight patients, none of the glands was scored as 2 (White) and all these patients developed hypocalcemia requiring calcium infusion.

Conclusion

The absence of visualization of at least 1 well-perfused (score 2) gland on ICG angiography is highly predictive of hypocalcemia and the majority of patients with total ICG score ≤5 developed hypocalcemia in the immediate postoperative period. ICG is a good predictor of the absence of hypoparathyroidism after thyroidectomy and is comparable to iPTH in the prediction of post-thyroidectomy hypocalcemia.

Extent of thyroidectomy and paratracheal lymph node dissection in total pharyngolaryngectomy for pyriform sinus cancer, and recurrence, survival, and postoperative hypoparathyroidism: A multicenter retrospective study

BACKGROUND

Total pharyngolaryngectomy (TPL) is standard treatment for hypopharyngeal cancer. However, extensive thyroidectomy and paratracheal nodal dissection (PTND) can cause hypoparathyroidism. We sought to determine the optimum extent of resection.

METHODS

We analyzed the clinicopathological information of 161 pyriform sinus cancer patients undergoing TPL from 25 Japanese institutions. Rates of recurrence and risk factors for hypoparathyroidism, as well as incidence of pathological contralateral level VI nodal metastasis and stomal recurrence, were investigated.

RESULTS

The extent of thyroidectomy and nodal dissection were not independent risk factors for recurrence. Incidences of contralateral level VI nodal involvement and stomal recurrence were 1.8% and 1.2%, respectively. Patients undergoing hemithyroidectomy/ipsilateral PTND did not develop stomal recurrence and had the lowest incidence of hypoparathyroidism. Prognosis in patients without tracheostomy prior to hemithyroidectomy/ipsilateral PTND was comparable to that with more extensive resections.

CONCLUSIONS

Hemithyroidectomy/ipsilateral PTND may be sufficient for pyriform sinus cancer cases without tracheostomy.

Avoiding Complications of Thyroidectomy: Preservation of Parathyroid Glands

Preservation of functional parathyroid glands during thyroidectomy and central neck surgery is crucial to avoid the common but serious complication of hypoparathyroidism. The first requirement is a solid foundational knowledge of anatomy and embryology which then enables the surgeon to use meticulous anticipatory dissection with identification and preservation of blood supply to the parathyroids. When preservation of blood supply is not possible, autotransplantation should be performed. New technologies harnessing the natural phenomenon of parathyroid autofluorescence to detect parathyroid tissue and indocyanine green to perform angiography may lead to improved outcomes with low risk to patients.

Distribution of inadvertently excised parathyroid glands during thyroid surgery and the link with post-surgical hypoparathyroidism

OBJECTIVES

To evaluate the incidence of inadvertent parathyroidectomy, identify risk factors, determine the location of inadvertently excised glands, review pathology reporting in inadvertent parathyroidectomy, and explore relationships between inadvertent parathyroidectomy and post-surgical hypoparathyroidism or hypocalcaemia.

METHODS

A retrospective cohort study of 899 thyroidectomies between 2015 and 2020 was performed. Histopathology slides of patients who had an inadvertent parathyroidectomy and a random sample of patients without a reported inadvertent parathyroidectomy were reviewed.

RESULTS

Inadvertent parathyroidectomy occurred in 18.5 per cent of thyroidectomy patients. Central neck dissection was an independent risk factor (inadvertent parathyroidectomy = 49.4 per cent with central neck dissection, 12.0 per cent without central neck dissection, p < 0.001). Most excised parathyroid glands were extracapsular (53.3 per cent), followed by subcapsular (29.1 per cent) and intrathyroidal (10.9 per cent). Parathyroid tissue was found in 10.2 per cent of specimens where no inadvertent parathyroidectomy was reported. Inadvertent parathyroidectomy was associated with a higher incidence of six-month post-surgical hypoparathyroidism or hypocalcaemia (19.8 per cent who had an inadvertent parathyroidectomy, 7.7 per cent without inadvertent parathyroidectomy).

CONCLUSION

Inadvertent parathyroidectomy increases the risk of post-surgical hypoparathyroidism or hypocalcaemia. The proportion of extracapsular glands contributing to inadvertent parathyroidectomy highlights the need for preventative measures.

Comparing laser speckle contrast imaging and indocyanine green angiography for assessment of parathyroid perfusion

Accurate intraoperative assessment of parathyroid blood flow is crucial to preserve function postoperatively. Indocyanine green (ICG) angiography has been successfully employed, however its conventional application has limitations. A label-free method overcomes these limitations, and laser speckle contrast imaging (LSCI) is one such method that can accurately detect and quantify differences in parathyroid perfusion. In this study, twenty-one patients undergoing thyroidectomy or parathyroidectomy were recruited to compare LSCI and ICG fluorescence intraoperatively. An experimental imaging device was used to image a total of 37 parathyroid glands. Scores of 0, 1 or 2 were assigned for ICG fluorescence by three observers based on perceived intensity: 0 for little to no fluorescence, 1 for moderate or patchy fluorescence, and 2 for strong fluorescence. Speckle contrast values were grouped according to these scores. Analyses of variance were performed to detect significant differences between groups. Lastly, ICG fluorescence intensity was calculated for each parathyroid gland and compared with speckle contrast in a linear regression. Results showed significant differences in speckle contrast between groups such that parathyroids with ICG score 0 had higher speckle contrast than those assigned ICG score 1, which in turn had higher speckle contrast than those assigned ICG score 2. This was further supported by a correlation coefficient of -0.81 between mean-normalized ICG fluorescence intensity and speckle contrast. This suggests that ICG angiography and LSCI detect similar differences in blood flow to parathyroid glands. Laser speckle contrast imaging shows promise as a label-free alternative that overcomes current limitations of ICG angiography for parathyroid assessment.

Incidental parathyroidectomy during total thyroidectomy and functional parathyroid preservation: a retrospective cohort study

BACKGROUND

The published rate of incidental parathyroidectomy (IP) during thyroid surgery varies between 5.8% and 29%. The risk factors and clinical significance of postoperative transient hypocalcemia and permanent hypoparathyroidism are still debated. The aims of this study were to assess the clinical relevance of avoidable IP for transient hypocalcemia and permanent hypoparathyroidism, and to describe the risk factors for IP.

METHODS

This retrospective cohort study included 1,537 patients who had a one-step total thyroidectomy in a high-volume endocrine surgery center between 2018 and 2019. Pathology reports were reviewed for incidentally removed parathyroid glands. Intrathyroidal parathyroid glands were excluded from the study. Demographic characteristics, potential risk factors, and postoperative calcium and PTH levels were compared between IP and control groups.

RESULTS

Avoidable IP occurred in 234 (15.2%) patients. Patients with IP had a higher risk of transient hypocalcemia (17.9% vs. 11.5%, p = 0.006; odds ratio [OR] 1.68, 95% confidence interval [95% CI]1.16-2.45) and permanent hypoparathyroidism (4.7% vs. 1.6%, p = 0.002; OR 3.01, 95% CI 1.29-6.63) than patients without IP. Multivariate analysis showed that central lymph node dissection (CLND) and incidental removal of thymus tissue were independent risk factors for IP (OR 4.83, 95% CI 2.71-8.86, p < 0.001 and OR 1.72, 95% CI 1.02-2.82, p = 0.038).

CONCLUSIONS

Patients with IP were more likely to develop transient hypocalcemia and permanent hypoparathyroidism, indicating the clinical significance of avoidable IP for patients and the need for raising awareness among surgeons. Patients undergoing CLND are at a higher risk for IP, and should be adequately informed and treated. Any removal of thymus tissue should be avoided during CLND.

The magic mirror: a novel intraoperative monitoring method for parathyroid glands

The accurate detection of parathyroid glands (PGs) during surgery is of great significance in thyroidectomy and parathyroidectomy, which protects the function of normal PGs to prevent postoperative hypoparathyroidism and the thorough removal of parathyroid lesions. Existing conventional imaging techniques have certain limitations in the real-time exploration of PGs. In recent years, a new, real-time, and non-invasive imaging system known as the near-infrared autofluorescence (NIRAF) imaging system has been developed to detect PGs. Several studies have confirmed that this system has a high parathyroid recognition rate and can reduce the occurrence of transient hypoparathyroidism after surgery. The NIRAF imaging system, like a magic mirror, can monitor the PGs during surgery in real time, thus providing great support for surgeries. In addition, the NIRAF imaging system can evaluate the blood supply of PGs by utilizing indocyanine green (ICG) to guide surgical strategies. The NIRAF imaging system and ICG complement each other to protect normal parathyroid function and reduce postoperative complications. This article reviews the effectiveness of the NIRAF imaging system in thyroidectomies and parathyroidectomies and briefly discusses some existing problems and prospects for the future.

US Features of the Parathyroid Glands: An Intraoperative Surgical Specimen Study

Purpose

This study aimed to evaluate the US features of the parathyroid glands (PTGs) using surgical specimens of normal PTGs obtained during thyroid surgery.

Materials and Methods

This study included 34 normal PTGs from 17 consecutive patients who underwent thyroid surgery between December 2020 and March 2021. All normal PTGs were histologically confirmed by intraoperative frozen-section biopsy for autotransplantation. Surgically resected parathyroid specimens were scanned in sterile normal saline using high-resolution US prior to autotransplantation. The US features of echogenicity (hyperechogenicity or hypoechogenicity), echotexture (homogeneous or heterogeneous), size, and shape (ovoid or round) were retrospectively evaluated. The echogenicity of the three PTGs was compared with that of the thyroid parenchyma of the resected thyroid specimens in two patients.

Results

All PTGs showed hyperechogenicity similar to that of gauze soaked in normal saline. Homogeneous hyperechogenicity was observed in 32/34 (94.1%) patients, and the echogenicity of the three PTGs was hyperechoic compared with that of the thyroid parenchyma. The long diameter of the PTGs ranged from 5.1 mm to 9.8 mm (mean, 7.1 mm) and the shape of the PTGs was ovoid in 33/34 (97.1%) patients.

Conclusion

The echogenicity of normal PTG specimens was consistently hyperechoic, and the small ovoid homogeneously hyperechoic structure was a characteristic US feature of the PTGs.

Indocyanine green fluorescence guided resection of parathyroid adenoma of the carotid sheath: a case report and review of the literature

BACKGROUND

Ectopic parathyroid tissue can pose difficulties in diagnosis, management, and resection of adenomas in patients with hyperparathyroidism. The use of multimodal pre-operative imaging is recommended due to the diverse anatomic presentation of parathyroid adenomas and the potential presence of multiple adenomas. Resection failure still can occur, however, indocyanine green (ICG) fluorescence imaging is an intraoperative tool that has potential to help address this challenge. In the case which follows we demonstrate the use of ICG fluorescence imaging to assist in successful resection of a parathyroid adenoma located within the carotid sheath.

CASE DESCRIPTION

We present the case of a 75-year-old woman with primary hyperparathyroidism due to a parathyroid adenoma localized to the left carotid sheath, posterior to the carotid artery. Careful resection was aided by ICG fluorescence guidance allowing for complete resection and immediate postoperative restoration of normal parathyroid hormone and calcium levels. The patient had no peri-operative complications and had an unremarkable post-operative course.

CONCLUSIONS

The anatomical heterogeneity of parathyroid gland adenomas within and around the carotid sheath presents a unique diagnostic and surgical scenario; however, the use of intra-operative ICG, as presented in this case, has important implications for endocrine surgeons and surgical trainees alike. This tool provides improved intra-operative identification of the parathyroid tissue allowing for safe resection, especially in cases involving critical anatomical structures.

Dual-phase computed tomography for localization of parathyroid lesions in children and adolescents with primary hyperparathyroidism

BACKGROUND

Childhood and adolescent primary hyperparathyroidism (PHPT) is a rare disease caused by single adenomas in 65-94% of patients. In this patient group, there is no data on computed tomography (CT) for pre-operative parathyroid localization that may facilitate focused parathyroidectomy.

METHODS

Two radiologists reviewed dual-phase (nonenhanced and arterial) CT images of twenty-three operated children and adolescents [20:single-gland disease(SGD), 3:multi-glandular disease(MGD)] with proven histopathological PHPT. Percentage arterial enhancement (PAE) was calculated as [100*{arterial-phase Hounsfield unit (HU)-nonenhanced phase HU}/nonenhanced HU] of the parathyroid lesion(s), thyroid, and lymph node.

RESULTS

Dual-phase CT lateralized 100%, localized to the correct quadrant/site 85% SGD (including 3/3 ectopic), and identified 1/3 MGD. PAE (cutoff ≥ 112.3%) was sensitive (91.3%) and specific (99.5%) in distinguishing parathyroid lesions from local mimics (P<0.001). The average effective dose was 3.16±1.01mSv, comparable to the planar/single photon emission CT (SPECT) Technetium 99m(Tc)-sestamibi and choline positron emission tomography (PET)/CT scans. Solid-cystic morphology identified in 4 patients harboring pathogenic germline variants (3:CDC73, 1:CASR) may serve as a radiological clue to molecular diagnosis. Nineteen out of 20 (95%) patients with SGD who had undergone single gland resection based on pre-operative CT findings were in remission over a median follow-up of 18 months.

CONCLUSION

As most children/adolescents with PHPT have SGD, dual-phase CT protocols which reduce the effective radiation dose with high localization sensitivity for single parathyroid lesions may be a sustainable pre-operative imaging modality in this patient group.

Surgical Steps of Gasless Transaxillary Endoscopic Thyroidectomy: From A to Z

In the past 30 years, the incidence of differentiated thyroid cancer (DTC) has been increasing rapidly and has become one of the most common malignant tumors in females. Currently, the main surgical treatment for DTC is standard open thyroidectomy (SOT) via a traditional Kocher mid-cervical incision, but postoperative neck scarring was associated with significantly worse health-related quality of life (HRQOL) scores. To offer better cosmesis, robotic/endoscopic thyroidectomy via cervical, axillary, anterior chest, breast, postauricular, or transoral approaches have been developed over the past 20 years. In general, gasless transaxillary endoscopic thyroidectomy (GTET) has advantages in terms of convenience, clarity of vision, and aesthetic incision. The current work aims to provide a step-by-step description of GTET, supported by a high-quality, pictorial guide.

Case Report: Primary Hyperparathyroidism due to Posterior Mediastinal Parathyroid Adenoma With One-Year Follow-Up

Ectopic parathyroid adenoma, though rare, is one of the causes of persistent hyperparathyroidism and recurrence of hyperparathyroidism. Ectopic parathyroid glands can be seen in thymus, thyroid, and mediastinum. However, ectopic parathyroid adenoma occurred in the posterior superior mediastinum is extremely rare. Here, we report a case of primary hyperparathyroidism caused by ectopic parathyroid adenoma located in the posterior superior mediastinum. Serum parathyroid hormone, calcium, and vitamin D levels of the patient was followed up for one year.

Ectopic Pleural Parathyroid Adenoma Causing Recurrent Primary Hyperparathyroidism

Ectopic parathyroid glands can cause primary hyperparathyroidism (PHPT) in up to 16% of cases. These can lead to recurrent/persistent PHPT, and multiple cases have been described in the literature. We present a case of a pleural parathyroid adenoma leading to persistent PHPT. The ectopic location of the parathyroid glands is a result of their migration during development and is next to tissues they share a common embryologic origin with. The pleural location of the parathyroid adenoma in our patient was highly unusual, as the pleura have an embryologically distinct origin from the parathyroids. This was likely the result of incomplete removal of a previous mediastinal adenoma or seeding of abnormal cells in the surrounding tissue due to capsular breach (parathyromatosis). These can lead to recurrent/persistent PHPT. Parathyromatosis can lead to the presence of adenomas in highly unusual locations, making diagnosis and treatment difficult. To our knowledge, this is the first reported case in the literature of pleural adenoma causing persistent PHPT.

Histone Modification on Parathyroid Tumors: A Review of Epigenetics

Parathyroid tumors are very prevalent conditions among endocrine tumors, being the second most common behind thyroid tumors. Secondary hyperplasia can occur beyond benign and malignant neoplasia in parathyroid glands. Adenomas are the leading cause of hyperparathyroidism, while carcinomas represent less than 1% of the cases. Tumor suppressor gene mutations such as MEN1 and CDC73 were demonstrated to be involved in tumor development in both familiar and sporadic types; however, the epigenetic features of the parathyroid tumors are still a little-explored subject. We present a review of epigenetic mechanisms related to parathyroid tumors, emphasizing advances in histone modification and its perspective of becoming a promising area in parathyroid tumor research.

Variation in parathyroid adenoma size in patients with sporadic, primary hyperparathyroidism: small gland size does not preclude single gland disease

PURPOSE

Small, abnormal parathyroid glands are usually associated with multigland hyperplasia in patients with primary hyperparathyroidism (pHPT). The purpose of this study was to determine the association between parathyroid adenoma size and biochemical cure rates in patients undergoing single gland parathyroidectomy.

METHODS

The study included patients with sporadic pHPT who underwent initial parathyroidectomy and met intraoperative PTH criteria for cure after resection of a single adenoma (SGD). Patients were divided into quartiles (Q1 = smallest) based on gland weight and maximum dimension; cure rates were compared across groups.

RESULTS

A single parathyroid adenoma was removed in 517 patients, with a median gland weight of 500 mg (range 50-11890). Median maximum gland dimension was 15 mm (range 5-55). With median follow-up of 28 months (range 6-81), the biochemical cure rate was 97.1%. There was no difference in cure rate by gland weight (Q1 94.6%, Q2 96.9%, Q3 98.4%, Q4 98.5%, p = 0.217) or maximum gland dimension (Q1 95.6%, Q2 97.6%, Q3 97.1%, Q4 98.2%, p = 0.641). When Q1 patients (by gland weight) were divided by quartile, there was no difference in cure rates (93.1% [50-140 mg]; 95.2% [150-190 mg]; 97.1% [200-230 mg]; 93.3% [240-280 mg]; p = 0.665).

CONCLUSION

For patients with pHPT who underwent single gland parathyroidectomy, there was no difference in cure rates by gland weight or maximum dimension. These data suggest that the removal of parathyroid adenomas as small as 50 mg with an appropriate decline in ioPTH likely represent single gland disease and additional exploration may not be necessary.

Contemporary Management of Primary Hyperparathyroidism

Primary hyperparathyroidism can be asymptomatic or symptomatic, as well as classic, normocalcemic, or normohormonal. It is important to rule out other causes of hypercalcemia or hyperparathyroidism. Preoperative localization with imaging is necessary for a minimally invasive approach and can be helpful even if planning 4-gland exploration. There are a variety of intraoperative techniques that can assist with localization as well as confirming success. Standard of care remains surgical resection of affected glands. However, there are less invasive management strategies that can be considered for poor surgical candidates.

Parathyroid Imaging: Past, Present, and Future

The goal of parathyroid imaging is to identify all sources of excess parathyroid hormone secretion pre-operatively. A variety of imaging approaches have been evaluated and utilized over the years for this purpose. Ultrasound relies solely on structural features and is without radiation, however is limited to superficial evaluation. 4DCT and 4DMRI provide enhancement characteristics in addition to structural features and dynamic enhancement has been investigated as a way to better distinguish parathyroid from adjacent structures. It is important to recognize that 4DCT provides valuable information however results in much higher radiation dose to the thyroid gland than the other available examinations, and therefore the optimal number of phases is an area of controversy. Single-photon scintigraphy with 99mTc-Sestamibi, or dual tracer 99mTc-pertechnetate and 99mTc-sestamibi with or without SPECT or SPECT/CT is part of the standard of care in many centers with availability and expertise in nuclear medicine. This molecular imaging approach detects cellular physiology such as mitochondria content found in parathyroid adenomas. Combining structural imaging such as CT or MRI with molecular imaging in a hybrid approach allows the ability to obtain robust structural and functional information in one examination. Hybrid PET/CT is widely available and provides improved imaging and quantification over SPECT or SPECT/CT. Emerging PET imaging techniques, such as 18F-Fluorocholine, have the exciting potential to reinvent parathyroid imaging. PET/MRI may be particularly well suited to parathyroid imaging, where available, because of the ability to perform dynamic contrast-enhanced imaging and co-registered 18F-Fluorocholine PET imaging simultaneously with low radiation dose to the thyroid. A targeted agent specific for a parathyroid tissue biomarker remains to be identified.

In Situ Preservation of Parathyroid Gland With Vasculature for Papillary Thyroid Carcinoma Is Associated With Higher PTH Levels After Total Thyroidectomy

PURPOSE

To evaluate the impact of parathyroid gland vasculature preservation in-situ technique (PGVPIST) on postoperative parathyroid hormone (PTH) and calcium plasma levels in thyroid patients undergoing total thyroidectomy for papillary thyroid carcinoma (PTC).

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients with PTC who underwent total thyroidectomy by either the conventional technique (group 1, January 2019 to January 2020) or PGVPIST (group 2, January 2020 to January 2021) were compared. Postoperative blood calcium levels and PTH levels were assessed in these groups.

RESULTS

Totally 149 patients with consecutive PTC underwent total thyroidectomy, including 60 patients in group 1 and 89 patients in group 2. Postoperative serum calcium levels in group 1 were insignificantly lower than in group 2 at day 1 (2.18 ± 0.02 vs 2.15 ± 0.01 mmol/L) and day 30 (2.27 ± 0.02 vs 2.38 ± 0.11) after surgery. But postoperative serum PTH levels in group 1 were significantly lower than that in group 2 at day 1 (23.68 ± 2.54 vs 31.46 ± 2.11 pg/mL) and day 30 (45.63 ± 3.21 vs 55.65 ± 2.89 pg/mL) after surgery.

CONCLUSION

Parathyroid gland vasculature preservation in-situ technique for PTC is associated with higher PTH level after total thyroidectomy. The parathyroid gland vasculature mostly strongly adheres with adjacent thyroid parenchyma. Therefore, deferred processing of tiny thyroid parenchyma of parathyroid gland vessels is essential to prevent devascularization.

Recurrent Hyperparathyroidism Following Successful Four-Gland Parathyroidectomy and Normalization of Parathyroid Hormone in a Renal Transplant Patient

Chronic kidney disease has an estimated prevalence of 10% in Australia and is predicted to rise in the coming years. Secondary hyperparathyroidism resulting from chronic kidney disease is an important cause of morbidity in these patients; and screening for secondary hyperparathyroidism is recommended in international guidelines. We present the case of a chronic kidney disease patient who developed recurrent hyperparathyroidism despite previous “total” parathyroidectomy and subsequent renal transplant. After targeted investigations he was diagnosed with an accessory parathyroid gland in his thorax, causing the recurrent hyperparathyroidism. He was managed with a thoracoscopic excision with a resultant drop in parathyroid hormone consistent with surgical cure. This case highlights the rare phenomenon of supernumerary and ectopic parathyroid glands. Cross sectional thoracic imaging can and should be used to detect and localize supernumerary glands not apparent at the time of original surgery.

Ultrasound Imaging of Cervical Anatomic Variants

Embryologic developmental variants of the thyroid and parathyroid glands may cause cervical anomalies that are detectable in ultrasound examinations of the neck. For some of these developmental variants, molecular genetic factors have been identified. Ultrasound, as the first-line imaging procedure, has proven useful in detecting clinically relevant anatomic variants. The aim of this article was to systematically summarize the ultrasound characteristics of developmental variants of the thyroid and parathyroid glands as well as ectopic thymus and neck cysts. Quantitative measures were developed based on our findings and the respective literature. Developmental anomalies frequently manifest as cysts that can be detected by cervical ultrasound examinations. Median neck cysts are the most common congenital cervical cystic lesions, with a reported prevalence of 7% in the general population. Besides cystic malformations, developmental anomalies may appear as ectopic or dystopic tissue. Ectopic thyroid tissue is observed in the midline of the neck in most patients and has a prevalence of 1/100,000 to 1/300,000. Lingual thyroid accounts for 90% of cases of ectopic thyroid tissue. Zuckerkandl tubercles (ZTs) have been detected in 55% of all thyroid lobes. Prominent ZTs are frequently observed in thyroid lobes affected by autoimmune thyroiditis compared with normal lobes or nodular lobes (P = 0.006). The correct interpretation of the ultrasound characteristics of these variants is essential to establish the clinical diagnosis. In the preoperative assessment, the identification of these cervical anomalies via ultrasound examination is indispensable.

Methods of identification of parathyroid glands in thyroid surgery: A literature review

Intra-operative identification and preservation of parathyroid glands is an important but challenging aspect of thyroid surgery. Failure to do so may lead to transient or permanent hypocalcaemia, where the latter represents a serious complication causing life-long morbidity. It would be beneficial, therefore, if a simple and reliable modality can be developed to assist in the identification of parathyroid glands intra-operatively. The aim of this literature review is to provide an overview of intra-operative modalities used to identify parathyroid glands with a particular focus on near-infrared autofluorescence (NIRAF). Twenty-seven studies were considered relevant in this literature review. Several modalities have been used to aid parathyroid gland identification, including Raman spectroscopy, indocyanine green angiography, and NIRAF. NIRAF technology allows parathyroid glands to spontaneously give off light (autofluorescence) when exposed to near-infrared light at a wavelength of 785 nm, creating a contrast between tissues to allow intra-operative differentiation. Studies utilising NIRAF technology were able to identify 76.3%-100% of parathyroid glands intra-operatively. Furthermore, two randomised controlled trials comparing NIRAF and white light showed that the use of NIRAF was able to significantly increase the mean number of parathyroid glands detected and reduce the incidence of post-operative hypocalcaemia. NIRAF is an emerging tool that has been shown to increase the number of intra-operative parathyroid gland identification and reduce the rate of post-operative hypocalcaemia in a safe and reproducible manner. Future trials are needed to evaluate the real-life impact of NIRAF technology in outcomes of patients following thyroid surgery.

Enlarged Parathyroid Glands on Trauma Computed Tomography: Frequency and Assessment for Possible Primary Hyperparathyroidism

OBJECTIVES

The aims of the study were to determine the frequency of enlarged parathyroid glands among patients undergoing trauma computed tomography (CT) who fall within the typical primary hyperparathyroidism (PHPT) age range and to assess for evidence of PHPT.

METHODS

For this retrospective study of 336 emergency department patients, concurrent cervical spine CT and neck CT angiography (CTA) examinations were reviewed for visible parathyroid glands. When visible, estimated weight was calculated, and a PHPT likelihood category was assigned after medical record review.

RESULTS

At least 1 parathyroid gland was visible in 17 patients (5%) and enlarged (estimated weight > 60 mg) in 11 (3%). Patients classified as "highly likely" or "likely" of having PHPT exhibited larger glands (median, 355 mg) than those classified as "unlikely" or "highly unlikely" (median, 47 mg; P = 0.01).

CONCLUSIONS

Parathyroid glands were enlarged in 3% of our cohort. Although PHPT likelihood seems to increase with gland size, definitive determination requires both serum calcium and serum parathyroid hormone.

The EANM practice guidelines for parathyroid imaging

INTRODUCTION

Nuclear medicine parathyroid imaging is important in the identification of hyperfunctioning parathyroid glands in primary hyperparathyroidism (pHPT), but it may be also valuable before surgical treatment in secondary hyperparathyroidism (sHPT). Parathyroid radionuclide imaging with scintigraphy or positron emission tomography (PET) is a highly sensitive procedure for the assessment of the presence and number of hyperfunctioning parathyroid glands, located either at typical sites or ectopically. The treatment of pHPT is mostly directed toward minimally invasive parathyroidectomy, especially in cases with a single adenoma. In experienced hands, successful surgery depends mainly on the exact preoperative localization of one or more hyperfunctioning parathyroid adenomas. Failure to preoperatively identify the hyperfunctioning parathyroid gland challenges minimally invasive parathyroidectomy and might require bilateral open neck exploration.

METHODS

Over a decade has now passed since the European Association of Nuclear Medicine (EANM) issued the first edition of the guideline on parathyroid imaging, and a number of new insights and techniques have been developed since. The aim of the present document is to provide state-of-the-art guidelines for nuclear medicine physicians performing parathyroid scintigraphy, single-photon emission computed tomography/computed tomography (SPECT/CT), positron emission tomography/computed tomography (PET/CT), and positron emission tomography/magnetic resonance imaging (PET/MRI) in patients with pHPT, as well as in those with sHPT.

CONCLUSION

These guidelines are written and authorized by the EANM to promote optimal parathyroid imaging. They will assist nuclear medicine physicians in the detection and correct localization of hyperfunctioning parathyroid lesions.

Complications after medullary thyroid carcinoma surgery: multicentre study of the SQRTPA and EUROCRINE® databases

BACKGROUND

Surgery is the curative therapy for patients with medullary thyroid carcinoma (MTC). In determining the extent of surgery, the risk of complications should be considered. The aim of this study was to assess procedure-specific outcomes and risk factors for complications after surgery for MTC.

METHODS

Patients who underwent thyroid surgery for MTC were identified in two European prospective quality databases. Hypoparathyroidism was defined by treatment with calcium/active vitamin D. Recurrent laryngeal nerve (RLN) palsy was diagnosed on laryngoscopy. Complications were considered at least transient if present at last follow-up. Risk factors for at-least transient hypoparathyroidism and RLN palsy were identified by logistic regression analysis.

RESULTS

A total of 650 patients underwent surgery in 69 centres at a median age of 56 years. Hypoparathyroidism, RLN palsy and bleeding requiring reoperation occurred in 170 (26·2 per cent), 62 (13·7 per cent) and 17 (2·6 per cent) respectively. Factors associated with hypoparathyroidism were central lymph node dissection (CLND) (odds ratio (OR) 2·20, 95 per cent c.i. 1·04 to 4·67), CLND plus unilateral lateral lymph node dissection (LLND) (OR 2·78, 1·20 to 6·43), CLND plus bilateral LLND (OR 2·83, 1·13 to 7·05) and four or more parathyroid glands observed (OR 4·18, 1·46 to 12·00). RLN palsy was associated with CLND plus LLND (OR 4·04, 1·12 to 14·58) and T4 tumours (OR 12·16, 4·46 to 33·18). After compartment-oriented lymph node dissection, N0 status was achieved in 248 of 537 patients (46·2 per cent).

CONCLUSION

Complications after surgery for MTC are procedure-specific and may relate to the unavoidable consequences of radical dissection needed in some patients.

Double ipsilateral parathyroid adenomas, with one supernumerary and ectopic at the same time: a case report

Background

Double adenomas (DA) represents a distinct clinical entity of primary hyperparathyroidism (PHPT). DA may follow various embryologic distribution patterns and could be supernumerary and/or ectopic.

Case presentation

We describe the first case of PHPT which comes as a result of double ipsilateral adenoma, of which one was both ectopic and supernumerary. A 45 year-old Greek male patient with diagnosed PHPT due to a single lower right parathyroid adenoma was admitted to our department for surgical treatment. The preoperative tests (neck US, Sestamibi scan) were conclusive for single gland disease. The patient underwent focused parathyroidectomy. The frozen section revealed a parathyroid adenoma with a slight possibility for parathyroid carcinoma. Ten minutes after the excision, intact PTH (iPTH) dropped >50% related to preoperative values and was within normal range. Right hemithyroidectomy with additional ipsilateral central neck dissection was performed, because of the possibility for parathyroid carcinoma. The final pathology report showed that the first excised tissue proved to be a parathyroid adenoma, while a second subcapsular one and a normal right upper parathyroid gland were also found.

Conclusions

Preoperative localization of DA using routine imaging tests and the utility of intraoperative parathyroid hormone assay are still unreliable in detecting multiple adenomas. Furthermore, a slight possibility of a second and simultaneously supernumerary and ectopic adenoma maybe present. Therefore, it would be advisable to establish the use of more advanced imaging tests (such as 4D-CT, 4D-MRI) or other diagnostic tools when DA are suspected.

Preoperative Localization for Primary Hyperparathyroidism: A Clinical Review

With increasing use of minimally invasive parathyroidectomy (PTx) over traditional bilateral neck exploration in patients with primary hyperparathyroidism (PHPT), accurate preoperative localization has become more important to enable a successful surgical outcome. Traditional imaging techniques such as ultrasound (US) and sestamibi scintigraphy (MIBI) and newer techniques such as parathyroid four-dimension computed tomography (4D-CT), positron emission tomography (PET), and magnetic resonance imaging (MRI) are available for the clinician to detect the diseased gland(s) in the preoperative workup. Invasive parathyroid venous sampling may be useful in certain circumstances such as persistent or recurrent PHPT. We review the diagnostic performance of these imaging modalities in preoperative localization and discuss the advantages and weaknesses of these techniques. US and MIBI are established techniques commonly utilized as first-line modalities. 4D-CT has excellent diagnostic performance and is increasingly performed in first-line setting and as an adjunct to US and MIBI. PET and MRI are emerging adjunct modalities when localization has been equivocal or failed. Since no evidence-based guidelines are yet available for the optimal imaging strategy, clinicians should be familiar with the range and advancement of these techniques. Choice of imaging modality should be individualized to the patient with consideration for efficacy, expertise, and availability of such techniques in clinical practice.

Comparison of 4DMRI and 4DCT for the preoperative evaluation of patients with primary hyperparathyroidism

BACKGROUND

Minimally invasive parathyroid surgery is the standard of care in patients with Primary Hyperparathyroidism (PHPT) which requires accurate preoperative localization. Of all the available imaging modalities, 4DCT is considered the best modality for localization, however it entails the risk of ionizing radiation. To circumvent this 4DMRI was evaluated for parathyroid lesion localization.

PURPOSE

To evaluate and compare the accuracy of 4DCT and 4DMRI in the localization of parathyroid Lesions.

MATERIALS AND METHODS

In this ethically approved observational diagnostic study, 135 patients (age range: 10-75 years, male: female ratio - 1:2.1) with clinically and biochemically suspected PHPT were recruited. Of these, 56 patients underwent both 4DCT and 4DMRI. Six patients with positive imaging who didn't undergo surgery were excluded. A total of 50 patients with 61 proven parathyroid lesions were included for analysis. 48 patients had surgical and histopathological findings for the confirmation of imaging findings.

RESULTS

Both 4DCT and 4DMRI correctly detected 59/61 lesions in 48 patients. There was one false positive and two true negatives. In addition, 2 (3.22 %) lesions which were not detected by 4DCT and 4DMRI were found on surgery. The sensitivity of both 4DCT and 4DMRI was 96.7 %; specificity was 66.6 % and accuracy was 95.2 %.

CONCLUSION

4DMRI and 4DCT had similar accuracy for the detection of parathyroid lesions. However, 4DMRI has the advantage of lack of exposure to ionizing radiation, which can be beneficial in younger patients.

Location and Vascular Classification of 188 parathyroid glands in New Zealand White Rabbits

ABSTRACT The function and protection of the parathyroid glands are increasingly popular research topics. New Zealand white rabbits are the most commonly used animal model of parathyroid ischemia. However, information on the vasculature of their parathyroid glands is limited. We used 94 healthy New Zealand white rabbits, 3-4 months of age and 2-3kg in weight, for exploration of the parathyroid glands, which were stained using hematoxylin and eosin (HE) after removal. The following types were classified according to the relationship between the position of the inferior parathyroid gland and the thyroid: Type A, Close Type, Type B, and Distant Type. There were 188 cases, 4 where the inferior parathyroid glands were located near the dorsal side of thyroid (2.13%), 8 where the inferior parathyroid glands were located superior to the upper pole of the thyroid (4.26%), 20 where the inferior parathyroid glands were located parallel to the thyroid (10.64%), and 155 cases where the inferior parathyroid glands were located inferior to the lower pole of thyroid (82.45%). Identifying the location and classifying the vasculature of the parathyroid glands in New Zealand white rabbits will provide an anatomical model to assist in future research.

Ectopic and supernumerary parathyroid glands in patients with refractory renal hyperparathyroidism

BACKGROUND

The aims of this study were to determine the rate of ectopic and supernumerary parathyroid glands and the outcome of surgical therapy in patients with refractory renal hyperparathyroidism.

MATERIALS AND METHODS

A retrospective review of all patients who underwent parathyroidectomy for refractory renal hyperparathyroidism was completed. Operative and pathology reports were reviewed, and the number and location of resected parathyroid glands, patient outcomes, and follow-up were determined.

RESULTS

During the period 1993-2019, a total of 68 patients underwent subtotal or total parathyroidectomy for renal hyperparathyroidism. Of those, 59 patients (87%) were on dialysis for an average of 6.7 years. We determined that 18 patients (26%) had 24 ectopic parathyroid glands, including 9 (13%) patients with 11 supernumerary glands. A total of 2 patients had a supernumerary gland in a normal anatomic location. Of the 24 ectopic glands, 14 (58%) were in the thymus. After parathyroidectomy, 4 patients (5.9%) had persistent hyperparathyroidism, 6 patients (8.8%) developed recurrent hyperparathyroidism, and 2 patients (3%) had permanent hypoparathyroidism.

CONCLUSION

Ectopic and supernumerary parathyroid glands occurred in 26% and 16% of patients with renal hyperparathyroidism, respectively, and the thymus was the most common location. Thorough neck exploration and transcervical thymectomy are important to help reduce persistent and recurrent hyperparathyroidism after parathyroidectomy for renal hyperparathyroidism.