Parathyroid adenomas in the aortopulmonary window

Primary hyperparathyroidism in pregnancy

Primary hyperparathyroidism (PHT) is a frequent and asymptomatic pathology in 80% of patients, and a parathyroidal adenoma is found in the most case. However, rare cases might occur during pregnancy; and the literature reported up to 200 cases. We report three cases of PHT that occurred during the second and last third trimesters of pregnancy stage in patients aged 26, 42 and 32-year-old. Despite diagnosis limitations, since scintigraphy is prohibited in pregnancy, the patients were managed conservatively with good prognosis for both mothers and babies.

Aortopulmonary window parathyroid gland causing primary hyperparathyroidism in men type 1 syndrome

Primary hyperparathyroidism (HPT) is the most common endocrinopathy in Multiple Endocrine Neoplasia type 1 (MEN1) syndrome. Supernumerary and/or ectopic parathyroid glands, potentially causes of persistent or recurrent HPT after surgery, have been previously described. However, this is the first ever described case of ectopic parathyroid gland localized in the aortopulmunary window causing HPT in MEN1. After a consistent concordant pre-operative imaging assessment the patient, a 16 years old male affected by a severe hypercalcemia, underwent surgery. The parathyroid was found very deeply near the tracheal bifurcation, hidden by the aortic arch itself and for this reason not visible at the beginning of the dissection but only after being identified by palpation for its typical consistence. The intraoperative PTH decreased at normal level 10 min after removal of the ectopic gland. The patient remained with normal value of calcemia and PTH during the 10 months of follow-up.

High cardiac background activity limits 99mTc-MIBI radioguided surgery in aortopulmonary window parathyroid adenomas

BACKGROUND

Radioguided surgery using 99m-Technetium-methoxyisobutylisonitrile (99mTc-MIBI) has been recommended for the surgical treatment of mediastinal parathyroid adenomas. However, high myocardial 99mTc-MIBI uptake may limit the feasibility of radioguided surgery in aortopulmonary window parathyroid adenoma.

CASE PRESENTATION

Two female patients aged 72 (#1) and 79 years (#2) with primary hyperparathyroidism caused by parathyroid adenomas in the aortopulmonary window were operated by transsternal radioguided surgery. After intravenous injection of 370 MBq 99mTc-MIBI at start of surgery, the maximum radioactive intensity (as counts per second) was measured over several body regions using a gamma probe before and after removal of the parathyroid adenoma. Relative radioactivity was calculated in relation to the measured ex vivo radioactivity of the adenoma, which was set to 1.0. Both patients were cured by uneventful removal of aortopulmonary window parathyroid adenomas of 4400 (#1) and 985 mg (#2). Biochemical cure was documented by intraoperative measurement of parathyroid hormone as well as follow-up examination. Ex vivo radioactivity over the parathyroid adenomas was 196 (#1) and 855 counts per second (#2). Before parathyroidectomy, relative radioactivity over the aortopulmonary window versus the heart was found at 1.3 versus 2.6 (#1) and 1.8 versus 4.8 (#2). After removal of the adenomas, radioactivity within the aortopulmonary window was only slightly reduced.

CONCLUSION

High myocardial uptake of 99mTc-MIBI limits the feasibility of radioguided surgery in aortopulmonary parathyroid adenoma.

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

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

Techniques for parathyroid localization with ultrasound

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

Diagnostic localization of ectopic parathyroid lesions: developmental consideration

Parathyroid glands arise from the third and fourth pharyngeal pouches. Parathyroid lesions sometimes develop ectopically. The aim of this article is to illustrate the knowledge of pharyngeal apparatus development to assist with diagnostic localization of ectopic parathyroid lesions. We retrospectively reviewed charts of 23 patients who received a diagnosis of ectopic parathyroid lesions. The ectopic lesions were widely distributed; cranially lesions were located on the carotid bifurcation, caudally in the right paraaortic region, ventrally on the surface of the sternohyoid muscle, and dorsally in the paraesophageal region. In most cases, parathyroid tissues were associated with structures related to the third or fourth pharyngeal pouches that traveled to regions where the ectopic lesions ultimately developed. In a few cases, lesions were not associated with these pouches and might have developed from parathyroid tissue that migrated due to an anomalous pathway of parathyroid travel. When patients present without entopic lesions, the presence of ectopic lesions should be evaluated based on an understanding of the developmental mechanisms of parathyroid glands and the frequency with which ectopic lesions have been found in specific locations. Systematic diagnosis can minimize the frequency with which ectopic lesions are missed during clinical care and maximize their accurate localization.

Multicenter study of 19 aortopulmonary window parathyroid tumors: the challenge of embryologic origin

BACKGROUND

Ectopic abnormal parathyroid glands are relatively common in the superior mediastinum but are rarely situated in the aortopulmonary window (APW). The embryological origin of these abnormal parathyroid glands is controversial. The purpose of this investigation was to investigate the embryological origin and the surgical management of abnormal parathyroid glands situated in the APW.

METHODS

The databases of patients operated on for primary, secondary, and tertiary hyperparathyroidism at eight European medical centers with a special interest in endocrine surgery were reviewed to identify those with APW adenomas. Demographic features, localization procedures, and perioperative and pathology findings were documented. The embryological origin was determined based on the number and position of identified parathyroid glands.

RESULTS

Nineteen (0.24%) APW parathyroid tumors were identified in 7,869 patients who underwent an operation for hyperparathyroidism (HPT) and 181 patients (2.3%) with mediastinal abnormal parathyroid glands. Ten patients had primary, eight had secondary, and one had tertiary HPT. Sixteen patients had undergone previous unsuccessful cervical exploration. In three patients, an APW adenoma was suspected by preoperative localization studies and was cured at the initial operation. Sixteen patients had persistent HPT of whom 15 were reoperated, resulting in 6 failures. Evaluation of 17 patients who had bilateral neck exploration allowed us to determine the most probable origin of the APW parathyroid tumors: 12 were supernumerary, 4 appeared to originate from a superior, and 1 from an inferior gland.

CONCLUSIONS

Abnormal parathyroid glands situated in the APW are rare and usually identified after an unsuccessful cervical exploration. Preoperative imaging of the mediastinum and neck are essential. The origin of these ectopically situated tumors is probably, as suggested by our data, from a supernumerary fifth parathyroid gland or from abnormal migration of a superior parathyroid gland during the embryologic development.

Minimally invasive parathyroidectomy: benefits and requirements of localization, diagnosis, and intraoperative PTH monitoring. long-term results

BACKGROUND

Surgery is the only curative treatment for primary hyperparathyroidism. Initial parathyroidectomy procedures fail due to ectopic gland location and unappreciated multigland disease.

METHODS

An evidence-based literature review was performed,which surveyed all human studies in PubMed, searching for parathyroidectomy in humans between 1990 and 2009. Between 10 and 30% of patients have multigland disease caused by double adenomas or hyperplasia. Use of preoperative imaging studies and intraoperative PTH monitoring helps parathyroid surgeons overcome these obstacles.

RESULTS

Sestamibi nuclear scan and neck ultrasound identify 70-80% of abnormal glands in patients with single adenomas. The sensitivity of ultrasound or sestamibi to identify all abnormal glands in patients with multigland disease is extremely low. Intraoperative PTH monitoring should be utilized in all patients who undergo neck exploration for primary hyperparathyroidism to reduce failures due to multigland disease. Blood samples should be drawn from peripheral veins only and a postresection level 10-15 min after gland removal should have a >50%decrease from baseline preoperative levels, and also must go to the normal range for the PTH assay being used.

CONCLUSIONS

Contemporary prospective studies (level of evidence III/IV) show that by combining preoperative imaging and IOPTH it is possible to maximize performance of successful outpatient minimally invasive parathyroidectomy.

Resection of ectopic mediastinal parathyroid glands with the da Vinci® robotic system

Background

Mediastinal ectopic parathyroid adenoma is a frequent cause of persistent or recurrent hyperparathyroidism, traditionally treated by open surgery. Thoracoscopic access is associated with reduced morbidity in mediastinal surgery. The aim of this study was to evaluate the feasibility and effectiveness of robot-assisted dissection for mediastinal ectopic parathyroid glands.

Methods

Two patients with recurrent secondary hyperparathyroidism and three with complicated primary hyperparathyroidism were operated on between July 2004 and August 2008 for ectopic mediastinal parathyroid glands. Fusion of single-photon emission computed tomography and computed tomography led to an exact identification of the culprit glands. Surgery was performed thoracoscopically with the da Vinci® robotic system using a three-trocar approach.

Results

All procedures were completed successfully with the robotic system. No perioperative morbidity or mortality was noted. Median operating time was 58 (range 42–125) min. Intraoperative parathyroid hormone reduction indicated complete resection. Median hospital stay was 3 (range 2–4) days.

Conclusion

Robot-assisted dissection is a promising approach for resection of ectopic parathyroid glands in remote narrow anatomical locations such as the mediastinum.

Hybrid SPECT/CT imaging for primary hyperparathyroidism: case reports and pictorial review

The utility of hybrid single photon emission computed tomography/computed tomography imaging for primary hyperparathyroidism is both intuitive and becoming increasingly apparent clinically, particularly for patients with prior failed surgery and for those with suspected ectopic adenomas. Second generation imaging equipment, capable of superimposing functional information on highly detailed anatomic images is proving useful in surgical planning, permitting the successful application of minimally invasive techniques. The clinical background and hybrid imaging modality are discussed, together with a selection of illustrative case images. Special emphasis is placed on the use of the technique for imaging ectopic parathyroid adenomas.

Accurate localization of supernumerary mediastinal parathyroid adenomas by a combination of structural and functional imaging

Reoperation for refractory or recurrent hyperparathyroidism following parathyroidectomy carries the potential for increased morbidity and the possibility of failure to localize and remove the lesion intraoperatively. Reported herein are three cases demonstrating the combined use of sestamibi scintigraphy, CT and MR for accurate localization of mediastinal parathyroid adenomas.

Imaging of the mediastinum: applications for thoracic surgery

The diagnostic approach to patients who have mediastinal masses should include thorough preoperative imaging. Once limited to plain radiographic techniques, the radiologist now has a wide variety of imaging modalities to aid in the evaluation of the mediastinum. CT is the imaging modality of choice for evaluating a suspected mediastinal mass or a widened mediastinum, and it provides the most useful information for the diagnosis, treatment, and evaluation of postoperative complications.

Middle mediastinal parathyroid: diagnosis and surgical approach

We report two cases of middle mediastinal parathyroid ectopia associated with chronic renal disease. In both patients the diagnosis was delayed and prolonged due to the unusual location of the ectopic parathyroid tissue. The surgical approach was in error in 1 patient and corrected during the second procedure. We describe the surgical technique for exposing and excising parathyroid tissue from this area.

Parathyroid imaging with Tc-99m sestamibi planar and SPECT scintigraphy

Technetium-99m sestamibi planar and single-photon-emission computed tomographic scintigraphy is useful in the diagnosis of parathyroid gland disease. To understand the various patterns of parathyroid disease, it is important to understand parathyroid embryology and anatomy. The spectrum of parathyroid disease demonstrated with Tc-99m sestamibi scintigraphy includes eutopic disease, ectopic disease, solitary adenoma, double or multiple adenomas, cystic adenoma, lipoadenoma, multiple endocrine neoplasia, hyperfunctioning parathyroid transplant, entities with atypical washout, and nonparathyroid entities that take up Tc-99m sestamibi. The diagnosis of parathyroid tumors with Tc-99m sestamibi scintigraphy is based on the difference in clearance rates between the thyroid and diseased parathyroid glands, and any condition that interferes with radiotracer clearance will limit the effectiveness of the study. The technique is most clearly indicated for the preoperative evaluation of recurrent or persistent hyperparathyroidism, but it is increasingly being used before the initial surgical exploration as well. Subtraction Tc-99m sestamibi and iodine-123 scintigraphy may be helpful in difficult cases. Parathyroid hyperplasia, multisite parathyroid disease, and concomitant thyroid and parathyroid disease remain potential hurdles for this scintigraphic technique, and optimal handling of these problems still relies heavily on the skill and experience of the endocrine surgeon.

Problems in endocrinologic imaging

Imaging particularly cross-sectional computer-assisted techniques such as CT and MR imaging, has become so refined and even breathtaking that the display of anatomy is beguiling endocrinologists into an unhealthy reliance on visual data. The demonstration of a focal abnormality in an endocrine gland tells us nothing about its function. Overreliance on such displays of anatomy leads to problems in diagnosis and treatment. This article points out some instances in which imaging is deceptive.

The role of thyroid resection during reoperation for persistent or recurrent hyperparathyroidism

BACKGROUND

The role of "blind" thyroid lobectomy in the surgical management of patients with persistent or recurrent primary hyperparathyroidism is not known. We reviewed our experience with reoperation for hyperparathyroidism to determine the utility of blind thyroid resection in this setting.

METHODS

From 1982 to 1995, 269 patients underwent reoperation for hyperparathyroidism at our institution. All patients had biochemical confirmation of hyperparathyroidism and underwent noninvasive and if necessary invasive localization studies. Patients who underwent thyroid lobectomy in an attempt to extirpate the hyperfunctioning parathyroid gland form the basis of this report.

RESULTS

Thirty-two of 269 patients (12%) underwent thyroid lobectomy to remove a parathyroid gland. Intrathyroidal parathyroids were confirmed in 19 of 32 patients (59%). In 18 of 19 patients (94%), preoperative or intraoperative ultrasonography correctly identified an intrathyroidal lesion suspicious or a parathyroid. Only 1 of 6 patients (17%) undergoing a blind thyroidectomy had an intrathyroidal gland identified. Ultrasonography had a sensitivity of 95% and a negative predictive value of 99.5% in detecting an intrathyroidal parathyroid gland.

CONCLUSIONS

The prevalence of an intrathyroidal parathyroid gland in our series is low (19 of 269, 7%). Ultrasonography can be used reliably to select patients for thyroid resection, reducing the need to perform a blind thyroid lobectomy and avoiding the potential morbidity of thyroid resection in this clinical setting.

Contrast-enhanced magnetic resonance imaging in a spinal epidural tumor model

RATIONALE AND OBJECTIVES

A spinal epidural tumor model was developed, using the VX-2 adenocarcinoma in rabbits, to assess the strengths and weaknesses of magnetic resonance (MR) as a cross-sectional imaging modality for the evaluation of epidural neoplastic disease. High-resolution MR images were acquired both before and after intravenous gadolinium chelate injection, assessing lesion detectability and efficacy of imaging technique.

METHODS

An adenocarcinoma tumor (VX-2) was produced in the epidural space of six New Zealand White rabbits and subsequently studied on a 1.5 tesla whole body MR scanner. VX-2 tumor tissue was removed from the thigh of a carrier rabbit, minced, and screened. Under fluoroscopic guidance, 0.2 mL of the tumor preparation was then injected into the epidural space of the experimental rabbits. The injection was performed at the L5-6 level using an epidural needle and polyethylene tubing sleeved within the needle. The rabbits were imaged using a circular small parts surface coil 5 to 15 days after the epidural injection. In all six animals, one complete MR exam was obtained within the time frame of days 9 to 11. T1- and T2-weighted axial scans were obtained before contrast injection, with the T1 scans acquired both with and without fat saturation. Postcontrast T1 scans also were obtained, using fat saturation, after the injection of 0.1 and 0.3 (cumulative dose) mmol/kg gadoteridol (Gd HP-DO3A; ProHance) in all animals. The film images were interpreted in a prospective fashion by a single neuroradiologist who was masked to imaging technique and contrast dosing. The digital data was analyzed by region of interest measurement. At the end of the imaging studies, the animals were sacrificed and the epidural lesion confirmed by gross and microscopic exam.

RESULTS

On a prospective masked read of the MR films, epidural tumor was depicted best on postcontrast fat saturation T1-weighted scans using a cumulative contrast dose of 0.3 mmol/kg. Substantial contrast enhancement of the tumor was observed in all instances on postcontrast scans. The precontrast T1-weighted scan was least efficacious for lesion identification and differentiation from the compressed spinal cord. Depending on the pulse sequence used, one (T2-weighted) to three (T1-weighted without fat saturation) of the lesions could not be identified prospectively on precontrast scans. Lesion growth with time after implantation was chronicled by MR imaging, accompanied by progression of symptoms. On region of interest analysis, differentiation of epidural tumor from normal cord was greatest (11.6 +/- 6.1) on postcontrast scans using a cumulative contrast dose of 0.3 mmol/kg. The level of differentiation achieved was twice that of postcontrast scans using a contrast dose of 0.1 mmol/kg (5.9 +/- 3.6). These results were superior on statistical analysis to that with all other scan techniques (P = 0.002-0.0005). Cord and tumor could not be differentiated on the basis of signal intensity, with any statistical significance, using precontrast T1 and T2 scans. The lesions were confirmed in each animal by gross and microscopic exam. On inspection of the gross specimen, the tumors were noted to be located in the epidural space and to cause cord compression. On microscopic exam, the tumor was composed of epithelial cells that were moderately pleomorphic.

CONCLUSIONS

In the New Zealand White rabbit, an epidural tumor could be created consistently using the described percutaneous approach. These lesions are suitable for MR imaging studies, examining lesion detectability and efficacy of imaging technique. The lesions created in the current study could not be diagnosed prospectively in all cases on precontrast T1 and T2 scans images. Postcontrast scans were most efficacious for diagnosis and lesion delineation, with high-dose (0.3 mmol/kg) scans superior to standard dose (0.1 mmol/kg).

SPECT and subtraction imaging of an ectopic parathyroid adenoma

Primary hyperparathyroidism is a disease best managed surgically; resection of the lesion(s) is curative. Although the routine use of localizing procedures is controversial before surgery, it is generally agreed that these techniques are useful in cases of reexploration. The authors have recently studied a patient with long-standing hyperparathyroidism, in whom initial surgery was unsuccessful. Although planar imaging with Tc-99m sestamibi is usually sufficient for identification and localization of the lesion, both SPECT and subtraction imaging provided additional information that contributed to the success of the subsequent surgery. Single-proton emission computed tomography provided critical information about the position of the ectopic parathyroid adenoma in relation to the right submandibular salivary gland, whereas subtraction imaging confirmed that the focus was indeed a parathyroid lesion, and not merely an anatomic variant of a normal salivary gland.