CASE 13575 Published on 28.08.2016

Parathyroid adenoma

Section

Head & neck imaging

Case Type

Clinical Cases

Authors

Lúcia Farracho, Max Scheffler

Department of Radiology,
Geneva University Hospitals,
Rue Gabrielle-Perret-Gentil 4,
1205 Geneva, Switzerland
Patient

88 years, female

Categories
Area of Interest Thyroid / Parathyroids ; Imaging Technique Ultrasound, Ultrasound-Colour Doppler, PET-CT
Clinical History
An 88-year-old woman with a history of right thyroidectomy twenty years before presented to the emergency department with weight loss and asthenia. Blood tests showed an elevated serum calcium level, elevated serum parathyroid hormone, as well as decreased serum vitamin D.
Imaging Findings
Initially, an ultrasound examination was performed. The grayscale images showed an 11 mm nodule of homogeneous hypoechoic echostructure posterior to the left thyroid lobe, separated from it by a fine echogenic capsule (Fig. 1a). On the colour Doppler ultrasound image, internal vascularity of the lesion was noted, with a peripheral predominance (Fig. 1b).
A technetium Tc-99m sestamibi (MIBI) parathyroid scintigram was then obtained, showing on the delayed images increased radiopharmaceutical uptake in the region of the nodule (Fig. 2a, 2b and 2c).
Discussion
Primary hyperparathyroidism (PHP) is defined as a state of parathormone (PTH) hypersecretion by a parathyroid gland, resulting in hypercalcaemia and hypophosphataemia [1]. It is one of the most common endocrine conditions worldwide with an estimated prevalence of 0.1%. Its most frequent cause is a parathyroid adenoma, a benign tumour [2, 3]. PHP has an increasing incidence in patients over 60 years. Women are affected 2-3 times more frequently than men.
80% of PHP patients are asymptomatic, with the condition incidentally detected by blood screening tests [1]. In symptomatic individuals, common presenting symptoms include fatigue, hypertension, bone pain, muscle weakness, and psychiatric illness [4]. Increased serum calcium and PTH levels are the main finding in the diagnostic process, and imaging studies are not mandatory. However, high-resolution ultrasound (US) represents a reliable modality for preoperative localization of parathyroid lesions, and it is often followed by a nuclear medicine imaging study for confirmation.
Typical ultrasound characteristics of parathyroid adenoma include a homogeneously hypoechoic echotexture on grayscale images, a large extrathyroidal feeding artery and peripheral vascularity on colour Doppler. Neck extension is useful during the examination as adenomata are commonly located inferior to the thyroid. Swallowing may improve the visualization of parathyroid adenoma in cases with a limited visual field [1]. For optimal results, neck ultrasound should be performed with a high frequency (7.5–15 MHz) transducer [3]. US alone may miss small lesions or ectopic glands and is difficult if a concomitant goitre is present, resulting in false negative findings. Most ectopic glands are found in typical locations including the paraesophageal space and thymic region [3]. Other locations include the carotid bifurcation or the region along the thyrothymic ligament [1]. Exophytic thyroid nodules may cause false positive results. The identification of the thyroid capsule separating the thyroid from a possibe adjadent parathyroid adenoma may help [1]. Studies comparing US and scintigraphy in the preoperative identification of a parathyroid adenoma have reported a sensitivity of 60-79% for US versus 77-88% for scintigraphy [1] with a false-positive rate of 8% for US versus 17% for scintigraphy [5]. When performed together, the sensitivity increases to 98% [6].
Surgery is the only curative option for symptomatic patients [2].
In conclusion, knowledge of typical imaging characteristics of enlarged parathyroid gland on ultrasound, coupled with a scintigraphic examination, may permit preoperative localization and provide a road map for the surgeon allowing for a focussed unilateral approach in appropriate cases.
Differential Diagnosis List
Parathyroid adenoma
Parathyroid hyperplasia
Eccentric thyroid nodule
Sequestered thyroid tissue
Lymph node
Parathyroid carcinoma
Final Diagnosis
Parathyroid adenoma
Case information
URL: https://www.eurorad.org/case/13575
DOI: 10.1594/EURORAD/CASE.13575
ISSN: 1563-4086
License