Parathyroid incidentaloma. Literature review about three case reports

Background

Parathyroid incidentaloma is not a well-known entity. The aim of this study was to show its incidence and to discuss its management.

Methods

This was a prospective study analyzing cases of enlarged parathyroid glands discovered during thyroid surgery. The records of patients with parathyroid incidentaloma were reviewed. We also reviewed all cases of primary hyperparathyroidism (HPTPs) operated during the same period for comparison.

Results

Three cases of enlarged parathyroid were found. No clinical or biochemical features led us to suspect hyperparathyroidism before surgery, but a macroscopically enlarged parathyroid gland was discovered during the dissection and was removed in all three patients.

Conclusions

Enlarged parathyroid glands discovered at the time of surgery may represent an early pathological stage responsible for overt primary hyperparathyroidism. In absence of major risk for recurrent nerve palsy, we recommend removal of any enlarged parathyroid discovered during neck surgery in order to avoid the risks of future surgical procedures, preserving in the same time at least one normal parathyroid gland.     

Historical Perspectives on Parathyroid Surgery

The field of parathyroid surgery is rich in history. It begins with an obscure publication by a Swedish medical student noting a distinct anatomic entity in the neck adjacent to the thyroid gland; these tiny glands would come to be known as the parathyroid glands. This was followed by the subsequent discovery of their role in calcium metabolism, once the devastating effects of hyperparathyroidism on the bones and kidneys were recognized. The first neck explorations with identification and removal of parathyroid adenomas took place in the early twentieth century. Following the initial parathyroid operations in the United States and Europe, the mid-twentieth century was dominated by extensive investigation into calcium metabolism and the effects of parathyroid hormone and by refinement of techniques in parathyroid surgery. In more recent years, the introduction of sophisticated localization studies and minimally invasive parathyroid operations continues to inspire progress in this unique and fascinating field. In this review, the sequence of events starting with the anatomic recognition of the parathyroid glands and ending with the most recent developments and advances in parathyroid surgery are described.     

Computerized axial tomography in the diagnosis and management of thyroid and parathyroid disorders

Computerized axial tomography (CAT) was used to study 39 patients with known thyroid disease and 14 patients with primary hyperparathyroidism. In all, CAT was performed only when information that was required for diagnosis or therapy was not available from other less expensive techniques. The greatest value was found in the evaluation of cryptic symptoms or structures in the neck after surgery for thyroid cancer, the assessment of the extent of thyroid cancer, the localization of aberrant thyroid tissue, the etiology of unexplained recurrent laryngeal nerve paralysis and the identification and delineation of mediastinal goiter. In six of 14 patients undergoing neck exploration for primary hyperparathyroidism CAT correctly localized the site of the enlarged parathyroid glands including one mediastinal parathyroid adenoma and one patient with two parathyroid adenomas.     

The role of parathyroid ultrasonography in the management of primary hyperparathyroidism

High-resolution, real-time sonography can be used to assess the size and location of the parathyroid glands. The authors review the types of information provided by sonography and outline the ways in which it contributes to the management of primary hyperparathyroidism. Sonography usually can differentiate parathyroid adenoma from hyperplasia. In milder cases, with less parathyroid enlargement, this differentiation is difficult but can be facilitated by determining three dimensions for each gland. Preoperative knowledge of the presumptive location of an adenoma is most useful when the strategy of unilateral neck exploration is to be used because it will allow the exploration always to begin on the correct side. Sonographic evidence of hyperplasia should trigger a preoperative search for multiple endocrine neoplasia and will alert the surgeon that a bilateral neck exploration and thymectomy will be needed. A more universal benefit is the ability to predict or exclude intrathyroidal and subcapsular parathyroid tumors, thus guiding the decision for thyroid versus thymic exploration in the event of a missing abnormal gland. Sonography often fails to visualize parathyroid tumors in an ectopic position away from the thyroid bed. Such tumors, however, may be anticipated when the sonogram shows only three enlarged glands in cases of hyperplasia, or only three glands of normal size in a patient with strong biochemical evidence of hyperparathyroidism. Because it is noninvasive and inexpensive and can provide a wealth of information, the authors have adopted sonography as a routine preoperative procedure for primary hyperparathyroidism.     

Ultrasonography for preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism: comparison with (99m)technetium sestamibi scintigraphy

OBJECTIVE: To determine the utility of ultrasonography for the preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism, and to compare this method with (99m)technetium sestamibi scintigraphy. DESIGN: The results of ultrasonography for localization of enlarged parathyroid glands were determined in 120 consecutive patients with primary hyperparathyroidism and compared with findings at surgery (n = 86) and with the results of (99m)technetium sestamibi scintigraphy (n = 99). PATIENTS: All patients had biochemically documented primary hyperparathyroidism based on elevated serum calcium and 'intact' parathyroid hormone measured by immunoassay. Patients with prior parathyroid surgery or secondary hyperparathyroidism were excluded. MEASUREMENTS: High-resolution ultrasonography was performed by a single observer. (99m)Technetium sestamibi scintigraphy was performed using early and delayed (2-h) views, and correlated with simultaneous thyroidal 123I uptake in most patients. RESULTS: Ultrasonography detected putative enlarged parathyroid glands in 92 of 120 unselected patients (77%). It correctly predicted surgical findings in 64 of 86 patients undergoing surgery (74%), including 61 of 72 patients with solitary eutopic parathyroid adenomas (84%), but only two of eight patients with solitary ectopic adenomas, and only one of six patients with multigland parathyroid disease. Sestamibi scintigraphy was positive in 87 of 99 unselected patients (88%), a higher proportion than ultrasonography (P < 0.05), reflecting superior sensitivity for the detection of ectopic parathyroid adenomas. For 74 patients undergoing parathyroid surgery who underwent both imaging tests there was no statistically significant difference between ultrasonography and sestamibi scintigraphy in ability to correctly predict surgical findings (74%vs. 82%, respectively) or in positive predictive value (93%vs. 90%, respectively). However, sestamibi scintigraphy was clearly more sensitive for ectopic parathyroid adenomas, providing correct localization in 8/8 cases. When one test was negative, testing with the second method was usually positive, improving the likelihood of a positive result to 98% when both tests were employed. CONCLUSIONS: Ultrasonography can be a sensitive and accurate method for preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism, comparable in overall utility to sestamibi scintigraphy. These results suggest that a strategy of initial testing with one or the other method, followed by the alternate imaging test if the first test is negative, would provide correct parathyroid imaging in most patients without prior parathyroid surgery.     

Utility of 99mTc-sestamibi scintigraphy as a first-line imaging procedure in the preoperative evaluation of hyperparathyroidism

OBJECTIVE The use of preoperative imaging in patients with hyperparathyroidism remains controversial. Many of the available techniques are insufficiently sensitive and specific to justify their routine use. We have evaluated the Sensitivity and specificity of ^99mTc-sestamibi scintigraphy in the management of patients with different forms of hyperparathyroidism. DESIGN Preoperative imaging evaluation was carried out by sclntigraphic detection of pathological parathyroid glands using ^99mTc-sestamibi as a radiotracer; confirmation of scan findings was obtained surgically. PATIENTS A group of 25 patients with primary (n= 21) or secondary (n=4) hyperparathyroidism were studied. All were considered for surgical treatment. MEASUREMENTS In all cases parathyroid imaging was carried out by ^99mTc-sestamibi scintigraphy together with at least one other imaging technique which included CT-scan, ultrasonography, MRI or ²⁰¹TI/^99mTc subtraction scintigraphy. Blood tests included measurements of total calcium and PTH. RESULTS ^99mTc-sestamibi scintigraphy correctly localized 20 out of 21 adenomas, giving a sensitivity of 95.2%, markedly higher than that obtained with the other imaging techniques (ultrasonography 75%, ²⁰¹TI/^99mTc subtraction scintigraphy 57.1%, CT-scan 41.7% and MRI 33%). Of a total of 17 glands identified surgically as hyperplastic and confirmed by pathological examination, ^99mTc-sestamibi scintigraphy showed a positive image in 10, corresponding always to the larger abnormal glands (sensitivity 58.8%, higher than that observed with the other techniques). No false positive images were obtained with ^99mTc-sestamibi. All the ectopic adenomas (n= 3) were identified preoperatively, which contributed significantly to the surgical approach. CONCLUSION In patients with hyperparathyroidism, ^99mTc-sestamibi scintigraphy may be used as the single imaging technique as it shows a very high sensitivity and specificity in the preoperative localization of pathological parathyroid glands; the benefit of localizing parathyroid tissue prior to surgery in cases of ectopic adenomas clearly indicates that when an imaging procedure is required, this technique may be of great help in the management of hyperparathyroidism.     

Eight parathyroid glands incidentally discovered during a surgical intervention for secondary hyperparathyroidism: an unusual clinical finding

Here we describe the uncommon case of a Caucasian male with secondary hyperparathyroidism due to 8 parathyroid glands discovered in the course of a surgical exploration. The patient (age 49 yr) with a 21-yr history of chronic renal failure came to our observation in June 1999 complaining of depression, muscle weakness, bone and joint pain, movement hindrance. The biochemical evaluation evidenced low-normal serum calcium, high phosphorus and PTH levels. The symptoms and the biochemical findings were suggestive for secondary hyperparathyroidism. The neck US revealed an increase of thyroid gland volume with diffuse hyperechogenity; two nodules of 20 and 25 mm as maximum diameter were found in the thyroid parenchyma, while 4 hypoechogenous nodules (maximum diameter ranging from 13.0 to 30.0 mm) with clean borders and anechogenous areas inside were evidenced in the rear side of the thyroid lobes. The parathyroid scan with 99mTc and 201 Tl demonstrated increased uptake bilaterally in the inferior side of the neck. The patient underwent a total parathyroidectomy with near total thyroidectomy in November 1999. Histological examination of surgical specimen evidenced 6 hyperplastic parathyroid glands in back side of the 2 lobes (3 on the right and 3 on the left), and the examination of the thyroid gland showed 2 hyperplastic parathyroids (5 mm and 15 mm maximum diameter) into the 2 nodules previously evidenced by US. The physiopathological and clinical and therapeutic implications of this observation are discussed.     

Presentation of 6 cases with parathyroid cysts and discussion of the literature.

INTRODUCTION: Cystic lesions of the parathyroid glands are uncommon, and rare are those that cause primary hyperparathyroidism. Preoperative diagnosis can be challenging and some of these tumors might be misinterpreted as parathyroid carcinoma. With an expertise of more than 1700 patients operated on primary hyperparathyroidism, we present six cases with cystic degeneration of a parathyroid gland causing primary hyperparathyroidism in five patients. CASE REPORTS: A woman at the age of 67 presented with hypercalcaemic crisis due to persistent primary hyperparathyroidism after an operation four years ago. As cervical exploration was unsuccessful, sternotomy was performed and a cystic adenoma of a parathyroid gland could be resected from the anterior mediastinum. The second patient - a 63-year-old female with severe hypercalcaemic crisis, operated on under suspicion of a parathyroid carcinoma - had a functional cyst of the parathyroid gland with a parathyroid hormone level of 700,000 pg/ml in the aspirated fluid. Third, operation on a 70-year-old woman with a benign euthyreot goiter and the laboratory findings of primary hyperparathyroidism revealed a cystic adenoma adjacent to the thyroid gland, whose aspirate had a parathyroid hormone level of 1,500,000 pg/ml. In the fourth case of a 67-year-old female with an adenoma of the right inferior parathyroid gland localized by ultrasonography, the cystic parathyroid adenoma was operated on by video-assistance. A cystic structure in the upper mediastinum was diagnosed in the fifth patient, a 66-year-old woman. It was suspected to be a thyroid cyst at the left-lower pole of the thyroid gland. After hemithyroidectomy pathological evaluation revealed a large parathyroid cyst. The last case of a 56-year-old male illustrates the extensive preoperative work-up of a patient with primary hyperparathyroidism who was preoperatively diagnosed as having a thyroid cyst. Final histopathological examination exposed multiple gland disease with a parathyroid adenoma as well as a cystic parathyroid gland. DISCUSSION: Cystic adenomas of the parathyroid glands are often misdiagnosed as thyroid cysts or - in the case of extremely elevated parathyroid hormone levels - even as parathyroid carcinoma. The routine preoperative diagnostic tools, such as ultrasonography or (99m)Tc-sestamibi-scintigraphy, cannot clearly distinguish between these entities and might be jeopardized by mediastinal localization, which is not uncommon in parathyroid adenomas with cystic degeneration.     

Technetium-99m tetrofosmin parathyroid imaging in patients with primary hyperparathyroidism

OBJECTIVE: To confirm the clinical significance of 99mTc-tetrofosmin imaging for the localization of hyperfunctioning parathyroid glands in patients with primary hyperparathyroidism. METHODS: All patients were imaged with 99mTc-tetrofosmin at 10 minutes and 2 hours after radiotracer injection, and with ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). The parathyroid/thyroid uptake ratio of 99mTc-tetrofosmin (P/T uptake ratio) was calculated. PATIENTS: Twenty patients with primary hyperparathyroidism were referred to our clinic, underwent surgical neck exploration or mediastinotomy and were diagnosed as having parathyroid adenoma. These patients were investigated for the preoperative localization by 99mTc-tetrofosmin scintigraphy. RESULTS: 99mTc-tetrofosmin imaging demonstrated focal uptake in 19 out of 20 patients with parathyroid adenoma. Two of the lesions were ectopic. US identified 17 parathyroid glands. CT and MRI initially detected 17 parathyroid glands. However, two additional parathyroid glands were localized on repeated CT and MRI in tandem with the results of the 99mTc-tetrofosmin imaging. Thus, the sensitivity and specificity of tetrofosmin imaging were 95% (19/20) and 95% (19/20); US, 85% (17/20) and 94% (16/17); initial CT, 85% (17/20) and 94% (16/17); and initial MRI, 88% (17/20) and 94% (16/17), respectively. The P/T uptake ratio at 2 hours after tetrofosmin injection was correlated with the serum concentration of intact PTH (rs=0.47, p<0.05) and the resected tumor weight (rs=0.53, p<0.05). CONCLUSION: 99mTc-tetrofosmin scintigraphy is useful for localization of parathyroid adenoma. Tetrofosmin uptake depends on the tumor weight and serum intact PTH levels.     

Parathyroid incidentaloma discovered during thyroid ultrasound imaging

We report two patients with incidentally discovered enlarged parathyroid glands while performing neck ultrasonography (US) for thyroid nodules. The parathyroid masses were seen as hypoechoic, homogeneous, oval nodules, separated from the thyroid gland. Both patients were completely asymptomatic, although subclinical evidence of hyperparathyroidism (serum PTH and calcium levels in the upper limit of the normal range, increased ionized serum calcium, osteocalcin, urinary calcium and hydroxyproline) was subsequently found in one patient. An enhanced uptake on sesta-MIBI scinti scan was concordant with the US finding in the two cases. PTH levels in the wash-out from the US-guided fine needle aspiration biopsy, confirmed the parathyroid origin of the lesions. Cytology and immunocytochemistry were, in our cases, unreliable diagnostic procedures. The extensive use of US imaging in thyroid pathology may increase the finding of US incidentally discovered parathyroid adenomas. The early detection of silent parathyroid pathologic findings may extend the natural history of these masses to a preclinical stage. Further investigations are necessary to evaluate the evolution of parathyroid incidentalomas and therefore their clinical significance.     

The role of imaging techniques in the study of renal osteodystrophy

Secondary hyperparathyroidism is the most common form of this condition found in renal osteodystrophy. Enlarged parathyroid glands are the rule in severe secondary hyperparathyroidism because of a marked parathyroid cell hyperplasia. For several years, ultrasonography, computed tomography, and scintigraphy with thallium201-technetium99 have been useful techniques to identify enlarged parathyroid glands. More recently, ultrasonography with color Doppler and parathyroid scintigraphy with 99mTc-sestamibi have proved to be useful as well. Computed tomography and magnetic resonance imaging can be used, but their sensitivity is similar to ultrasonography and they cost more. Ultrasonography with color Doppler signals has made it possible to evaluate tissue blood supply, an aid in differentiating thyroid nodules. The degree of blood supply may be an indirect index of cell proliferation when there is neither necrosis nor calcification, because an enriched blood supply suggests vigorous cell growth and nodule formation. Scintigraphy with 99mTc-sestamibi allows identification of ectopic glands, including those located in the mediastinum, and also provides functional information. Sestamibi uptake is closely related to both parathyroid hormone levels and to the histological type of parathyroid proliferation. In our experience, when hyperparathyroidism is not too severe, 2 weeks after 2 g of calcitriol is administered intravenously, these scintigraphic images can disappear (inhibition test). This suggests a possibility for a medical treatment. By contrast, when parathyroid hormone levels are higher, parathyroid sestamibi uptake remained unchanged. In such patients, parathyroidectomy or ethanol injection should be the best treatment. These glands would correspond to the most actively functioning glands; they would have a lesser expression of vitamin D receptors, rendering them refractory to medical treatment with calcitriol.     

Contribution of intra-operative measurement of intact parathormone in surgery for primary hyperparathyroidism]

Using a sensitive two-site immunoradiometric assay which detects intact parathormone (iPTH), we studied the decrease in peripheric and jugular plasmatic iPTH during surgical removal of abnormal parathyroid (s). In the next future, results of intact parathormone (iPTH) assay will be given in 45 minutes. In a prospective study of 33 patients operated on for hyperparathyroidism or for cold thyroid nodule, the serum levels of intact PTH was measured intraoperatively in peripheric and in jugular blood. The preoperative mean serum iPTH concentration was 119.23 +/- 172.48 pg/ml and fell to 34.5 +/- 32.21 pg/ml after surgery in 14 cases of primary hyperparathyroidism (p < 0.001). Thirteen out of 14 patients had serum iPTH values less than 65 pg/ml within 15 minutes after parathyroidectomy. The preoperative mean serum iPTH concentration in the 5 secondary hyperparathyroidism was 781.2 +/- 403.19 pg/ml. This value fell to 124 +/- 66.91 pg/ml after parathyroidectomy (p < 0.04). No significant decrease was observed in the mean serum concentration of the 14 patients operated on for cold thyroid nodule. Patients suffering from single parathyroid adenoma presented a significant gradient in jugular plasmatic PTH concentration between the adenoma side and the contralateral one. This gradient decreased during effective parathyroid adenomectomy (309.7 +/- 313.3 pg/ml to 3.7 +/- 35.1 pg/ml). Intraoperative serum iPTH concentration will provide a valuable tool to appreciate the effectiveness of surgical removal of parathyroid glands and to detect the location of parathyroid adenoma when the surgical research is negative.     

A quick intraoperative parathyroid hormone assay in the surgical management of patients with primary hyperparathyroidism: a study of 206 consecutive cases

OBJECTIVE: The traditional surgical approach for patients with primary hyperparathyroidism (PHPT) consists of the identification of at least four glands and in the removal of all hyperfunctioning parathyroid tissue. DESIGN: To evaluate whether intraoperative parathyroid hormone (PTH) monitoring will allow a more limited surgical procedure by confirming complete removal of all hyperfunctioning tissue. METHODS: Plasma samples were obtained from 206 consecutive patients with sporadic PHPT before skin incision, during manipulation of a suspected adenoma, and 5 min (T-5) and 10 min after removal of abnormal parathyroid tissue. PTH was measured by a quick immunochemiluminescent assay (QPTH). The operative success was defined by a decrease of PTH greater than 50% of the highest pre-excision value. RESULTS: A >50% decrease of PTH occurred in 203 patients and was evident at T-5 in the majority of cases. All but three had normal serum calcium the day after surgery and afterwards. PTH concentration did not show a >50% decrease in the remaining three cases after completion of surgery. One patients had negative neck exploration and remained hypercalcemic; the other two had normal serum calcium at follow-up. Thus, the intraoperative QPTH correctly predicted the outcome of surgery in 201 patients (97.5%) (200 true positive and 1 true negative), and provided three false positive and two false negative results. CONCLUSIONS: The intraoperative QPTH measurement represents a useful tool to assist the surgeon during parathyroidectomy. It indicates whether all hyperfunctioning parathyroid tissue has been removed, limiting the procedure to a unilateral neck exploration in most cases.     

Localization of parathyroid tumors using endoscopic ultrasonography in primary hyperparathyroidism

Parathyroid adenomas responsible for primary hyperparathyroidism may be difficult to detect preoperatively. Furthermore parathyroid adenomas may arise behind the (nodular) thyroid gland, in a deep cervical location, and plans should be plane. The purpose of the present prospective study was to evaluate echoendoscopy, and to compare its accuracy to that of non invasive tests. Fourteen consecutive patients with primary hyperparathyroidism were prospectively studied. All patients underwent echoendoscopy, ultrasonography (US), CT scanning or magnetic resonance imaging (MRI) and Tc 99m sestamibi scanning before undergoing initial neck exploration. The parathyroid pathology was a solitary adenoma in 13 patients and a 4 glands hyperplasia in one. All tests were corroborating in 5 cases. Four adenomas were localized to the correc tside (33%), and no test accurately localized all hyperplastic glands. EUS, sestamibi and CT scanning or MRI correctly identified 10 parathyroid tumors in 14 cases (71%). US correctly localized only 5 adenomas (sensitivity 36%). The sensitivity of EUS to detect parathyroid adenomas is superior to US (p<0.05) and comparable to that of other non invasive tests. We conclude that EUS may be an useful tool to localize parathyroid lesions. This method may replace US prior to initial neck exploration with further miniaturization of probes, or find an intermediate place among invasive and noninvasive preoperative localization procedures in patients with persistent or recurrent PHPT.     

Localising imaging in secondary hyperparathyroidism

Preoperative imaging has proved its use successful in the localization of solitary parathyroid adenomas in patients with suspected primary hyperparathyroidism. However, due to multiglandular disease at presentation patients with renal hyperparathyroidism need to be analyzed separately, making the usefulness of imaging techniques controversial. Recently, improved methods of functional imaging like parathyroid scan with 99mTc-sestamibi or positron emission tomography, especially when combined with computed tomography, can provide additional quantitative and qualitative information that has yet to be assessed. Nuclear medicine procedures could prove useful not only in preoperative diagnosis, but also in the selection of medical or surgical therapeutic alternatives in secondary hyperparathyroidism patients. There is evidence that 99mTc-sestamibi uptake in parathyroid hyperplasia or adenoma is related to biochemical markers of parathyroid function. We are only beginning to identify the factors involved in radiotracer uptake by parathyroid cells and how it can be modulated to obtain more accurate results. This review analyzes the current use of non-invasive imaging modalities in patients with secondary hyperparathyroidism, taking into account the latest trends in the field combining anatomic and functional modalities and the relevant factors linked to radiotracer uptake in abnormal hyperfunctioning parathyroid glands.     

Imaging techniques for identifying parathyroid tumors.

Recent advances in imaging techniques, including high-resolution sonography, parathyroid scintigraphy, computerized tomography, magnetic resonance imaging, venography and venous sampling, arteriography, and fine-needle aspiration biopsy, have made it possible consistently to identify parathyroid glands enlarged owing to adenoma formation, diffuse hyperplasia, or carcinoma. Whereas the routine use of these techniques in the previously unoperated patient with suspected hyperparathyroidism is debated, most experts would agree to their utility in patients with prior negative neck exploration in whom elevated serum calcium and parathyroid hormone persist.     

Ultrasonography in detection of single and multiple abnormal parathyroid glands in primary hyperparathyroidism: comparison with radionuclide scintigraphy and surgery

BACKGROUND: Among the parathyroid imaging techniques, ultrasonography (USG) has the advantage of convenience, easy availability and low cost. OBJECTIVE: To study the role of USG in localization (side and/or site) of abnormal parathyroid glands in primary hyperparathyroidism (PHPT) and to compare with radionuclide scintigraphy and the 'gold standard', surgery. METHODS: Forty-six consecutive patients undergoing USG of the anterior neck for a diagnosis of PHPT in whom a nuclear scan (technetium-99m sestamibi and/or thallium-201/technetium-99m pertechnetate scintigraphy) was also performed, were studied. The results of imaging were independently interpreted and correlated with reference to surgical findings. RESULTS: Forty-six patients had 52 abnormal parathyroid glands on surgical exploration and surgery was successful in all but one. Forty-one patients had a single adenoma, four had multigland disease and one had a paraganglioma. USG correctly localized the abnormal gland in 30 (73%) and scintigraphy was positive in 40 (98%) out of 41 patients with a single adenoma as confirmed on surgical exploration. Scintigraphy showed a positive concordant test in all 30 patients with a single abnormal gland detected on USG and picked up 10 out of 11 abnormal glands where USG was negative. The sensitivity and positive predictive value of USG for detecting a single abnormal gland was 73% and 100%, respectively, whereas the sensitivity and positive predictive value for scintigraphy was 98%. In patients with multigland disease, USG missed 3 (30%) out of 10 and scintigraphy missed 6 (60%) out of 10 abnormal parathyroid glands as confirmed on surgical exploration (P < 0.05). However, in two patients who had ectopic parathyroid gland, both the modalities localized the lesion in one (paraganglioma), whereas in the other neither test was helpful (left retro-esophageal). CONCLUSION: USG is a convenient, affordable and useful modality to localize abnormal enlarged parathyroid glands in the majority of patients with PHPT. However, when USG is negative, scintigraphy is complementary to it.     

Preoperative evaluation of parathyroid lesions in patients with concomitant thyroid disease: role of high resolution ultrasonography and dual phase technetium 99m sestamibi scintigraphy

The aim of this study was to evaluate the sensitivity and usefulness of high resolution ultrasonography (US) and dual phase technetium-99m sestamibi (Tc-MIBI) scintigraphy in the preoperative localization of parathyroid lesions in patients with or without thyroid disease and to define the impact of the presence of thyroid disease on these methods. Preoperative US and scintigraphy were performed on 52 patients with primary hyperparathyroidism. Age, gender, preoperative parathyroid hormone level, serum calcium level, serum phosphate level, diameter, location, associated with thyroid abnormality, and results of parathyroid exploration were determined in all patients. The results of US and Tc-MIBI imaging were analyzed and compared with surgical and histopathologic findings. At surgery, 56 parathyroid lesions were found in 52 patients (9 men, 43 women), the parathyroid lesion was solitary (47 adenomas, two hyperplasias), in 2 patients double adenomas were present, in 1 patient three glands was affected by hyperplasia. Twenty-seven patients had concomitant thyroid disease. The overall sensitivity of US and Tc-MIBI scintigraphy was 84% and 73%, respectively. In patients without thyroid disease, the sensitivity of these techniques was 90% and 75%, respectively. In patients with thyroid disease, the sensitivity was 78% and 70%, respectively. In patients with thyroid disease, the combined sensitivity of these techniques was 89%. These results allow the conclusion that, in experienced hands, US is a highly sensitive technique. Especially in patients with no thyroid pathology and typical located gland, US alone should be used as a first step for preoperative localization of parathyroid lesions. When negative, Tc-MIBI scintigraphy is suggested. In patients with concomitant thyroid disease, the combination of US and Tc-MIBI scintigraphy represents a reliable localization technique.     

Controversies on minimally invasive procedures for radio-guided surgery of parathyroid tumours

The definitive treatment of primary hyperparathyroidism (PHPT) is the surgical approach which traditionally consists of bilateral neck exploration with visualization of at least 4 parathyroid glands and removal of the enlarged ones. However, the most frequent cause of PHPT is a solitary parathyroid adenoma so that a limited neck exploration in order to remove the solitary adenoma alone appears adequate to many surgeons. The recent significant improvements achieved in the pre-operative parathyroid localization techniques, mainly the parathyroid scintigraphy, and the introduction in surgical practice of measurement of quick parathyroid hormone, endoscopic procedures, and intra-operative gamma probes used together specific radiopharmaceuticals allowed to offer the PHPT patient a limited neck exploration as the unilateral neck exploration and the minimally invasive parathyroidectomy. The present article deals with the role of the intra-operative gamma probes used together with specific radio-pharmaceuticals, discussing the principal advantages and disadvantages of each currently used radio-guided approach.     

Multimodality imaging of the parathyroid glands in primary hyperparathyroidism

Primary hyperparathyroidism is a common endocrine disorder, affecting approximately 1 in 500 women and 1 in 2,000 men. Surgical removal of the hyperfunctioning parathyroid gland is the primary curative treatment. The last decade has witnessed the development of minimally invasive parathyroidectomy, which is based on the fact that the vast majority of cases are caused by single adenomas. However, the success of this technique relies on accurate preoperative localisation of the parathyroid lesions. The imaging modalities used vary at different institutions according to local expertise and availability, but include high resolution ultrasound, radionuclide studies, computed tomography (CT) and magnetic resonance imaging (MRI). Ultrasound and 99mTc sestamibi scintigraphy, particularly when complemented by single photon emission computed tomography (SPECT), are currently the imaging techniques of choice for preoperative localisation of parathyroid adenomas; a combination of the two methods further improves the sensitivity and accuracy of detection. CT is less commonly used for preoperative localisation and usually reserved for cases of failed parathyroidectomy, for the detection of suspected ectopic glands. MRI appears to be useful in patients with persistent or recurrent hyperparathyroidism, who have previously undergone surgery. Cross-sectional imaging is also useful in cases where the findings at sonography and scintigraphy are discordant. SPECT/CT appears promising, but further studies are needed to evaluate its role in preoperative localisation.