How Far Should We Search for Parathyroıd Adenoma?

Primary hyperparathyroidism is one of the most common endocrine disorders. It happens when the parathyroid glands make too much Parathyroid Hormone (PTH), which causes hypercalcemia. Over the past few decades, the clinical presentation has changed a lot [1]. Most patients now have asymptomatic hypercalcemia instead of the classic signs of bone disease and nephrolithiasis [2]. There are three main causes of primary hyperparathyroidism: Solitary parathyroid adenoma (about 85% of cases), multiglandular hyperplasia (10-15%) and parathyroid carcinoma (1-2%). Most parathyroid adenomas are in the right places in the body, but ectopic adenomas can make diagnosis and treatment harder. It is thought that ectopic parathyroid adenomas make up 4-16% of all cases of primary hyperparathyroidism and are a major reason why neck exploration fails [3]. These adenomas can be found in many places in the body, such as the thymus, mediastinum, carotid sheath, retroesophageal space, or even inside the thyroid. Mediastinal adenomas make up only 1-5% of all ectopic parathyroid adenomas, but they need special care because of where they are and how easy they are to reach for surgery. Not only is the right surgical technique important for treating primary hyperparathyroidism, but so is finding the adenoma in the right place before surgery [4]. This case report shows how important advanced imaging techniques are for finding ectopic parathyroid adenomas when standard imaging methods don’t work.

Patient history and clinical presentation

A 47-year-old female patient was referred to our Endocrinology clinic due to asymptomatic hypercalcemia discovered during routine laboratory screening [5]. The patient had a significant medical history of recurrent nephrolithiasis but was not taking any medications at the time of presentation.

Laboratory investigations

Initial laboratory workup revealed:
A. Serum calcium: 11.43mg/dL (normal range: 8.6-10.0mg/ dL)
B. Parathyroid hormone (PTH): 459.7pg/mL (normal range: 15-65pg/mL)
C. 25-hydroxy vitamin D: 15ng/mL (normal range: 30- 100ng/mL)
D. 24-hour urine calcium: 395mg/day (normal range: 50- 200mg/day)

These findings were consistent with primary hyperparathyroidism, demonstrating elevated serum calcium and inappropriately elevated PTH levels, along with increased urinary calcium excretion.

Initial imaging

Based on the biochemical diagnosis of primary hyperparathyroidism, neck ultrasonography was performed as the initial imaging modality. However, no pathological findings were detected in the parathyroid region..

Advanced imaging

Given the negative initial ultrasonography, further imaging studies were pursued:
Parathyroid scintigraphy: This study was performed but showed no evidence of parathyroid adenoma.
Neck MRI: Magnetic resonance imaging of the neck was also negative for adenoma.
F-18 choline PET imaging: Due to the negative conventional imaging studies, F-18 Choline PET was performed at an external center [6]. This study revealed intense radiotracer uptake at the left cervical level 3, suspicious for ectopic parathyroid adenoma (Figure 1).

Figure 1:F-18 choline PET image.

Figure 2:Control USG image.

Targeted imaging

Following the F-18 Choline PET findings, repeat ultrasonography was performed specifically targeting the area of increased uptake. This targeted approach successfully identified the adenoma at the location suggested by the PET scan [7] (Figure 2).

Surgical management

Based on the successful localization of the ectopic parathyroid adenoma, the patient was referred to the general surgery team for surgical management [8]. The patient underwent successful surgical removal of the ectopic adenoma.

Clinical ımages

The case was documented with F-18 Choline PET imaging showing the area of intense uptake corresponding to the ectopic parathyroid adenoma, as well as targeted ultrasonography images confirming the adenoma location.

This case highlights several important aspects of managing primary hyperparathyroidism with ectopic parathyroid adenomas:

Diagnostic challenges

The initial negative imaging studies with conventional ultrasonography, parathyroid scintigraphy and neck MRI demonstrate the diagnostic challenges posed by ectopic parathyroid adenomas. These lesions can be difficult to detect with standard imaging protocols, particularly when they are located outside the typical parathyroid regions.

Role of advanced imaging

F-18 Choline PET imaging proved to be crucial in this case. This advanced imaging modality has emerged as a valuable tool for localizing parathyroid adenomas, particularly in cases where conventional imaging has failed. The high specificity of F-18 Choline for parathyroid tissue makes it particularly useful for detecting ectopic adenomas.

Importance of targeted approach

The success of repeat ultrasonography after F-18 Choline PET localization emphasizes the importance of a targeted imaging approach. When the general location of an adenoma is known from functional imaging, high-resolution anatomical imaging can provide detailed information necessary for surgical planning.

Clinical implications

Ectopic parathyroid adenomas represent a significant challenge in the management of primary hyperparathyroidism. Failed initial surgery due to unlocalized adenomas can lead to persistent disease, increased morbidity and the need for repeat surgical procedures. This case underscores the importance of thorough preoperative localization studies.

Surgical considerations

The successful surgical management of this case demonstrates that ectopic parathyroid adenomas can be effectively treated when properly localized. The cooperation between endocrinology and surgery teams is essential for optimal patient outcomes.

This case report demonstrates the importance of considering ectopic parathyroid adenomas in patients with primary hyperparathyroidism when conventional imaging fails to identify the source of excessive PTH secretion. The successful localization of the adenoma using F-18 Choline PET imaging, followed by targeted ultrasonography, led to successful surgical management.

Key learning points from this case include:
A. Ectopic parathyroid adenomas should be considered in patients with biochemical evidence of primary hyperparathyroidism but negative conventional imaging.
B. Advanced imaging techniques, particularly F-18 Choline PET, play a crucial role in localizing ectopic parathyroid adenomas.
C. A multidisciplinary approach involving endocrinology, nuclear medicine, radiology and surgery is essential for optimal patient outcomes.
D. The success of parathyroid surgery depends not only on surgical expertise but also on accurate preoperative localization of the adenoma.

This case contributes to the growing body of evidence supporting the use of advanced imaging modalities in the management of challenging cases of primary hyperparathyroidism and emphasizes the importance of persistent investigation when initial studies are negative.

This case report was prepared in accordance with ethical guidelines for case reporting. Patient confidentiality has been maintained throughout the preparation and presentation of this case. Written informed consent was obtained from the patient for publication of this case report.

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