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PARATHYROID ADENOMA
Authored By: Collin Liu and Jerold Wallis, Assoc Prof of Radiology.
Patient: 57 year old female
History:

57-year-old woman with hypercalcemia and hyperparathyroidism. The patient had a prior right parathyroidectomy for hyperparathyroidism.

Image Size:[small][as-submitted]

Fig. 1
Planar images at 10 min and 2 hours.

Fig. 2
SPECT at 15 minutes

Fig. 3
SPECT at 15 minutes

Fig. 4
SPECT at 15 minutes
Image Size:[small][as-submitted]

Findings:

Parathyroid Scintigraphy with SPECT-CT
Radiopharmceutical: 21.4 mCi Tc-99m sestamibi i.v.

On the initial images, the right thyroid lobe is absent. The left thyroid lobe is enlarged and multinodular, limiting assessment for a parathyroid adenoma, with areas of increased and slightly decreased uptake throughout the enlarged left lobe (Figure 1, first image).

 

On the SPECT-CT images there is also relative increased uptake in the posterosuperior aspect of the left thyroid lobe adjacent to the thyroid cartilage, (best seen on Figure 3) in the region described on the recent thyroid ultrasound (not shown) as suspicious for parathyroid adenoma.  Lesser diffuse increased uptake is seen in the thyroid (Figure 2, Figure 4).

 

The two-hour delayed planar images show a faint focus of persistent activity in this region (Figure 1, second image, seen as a tiny focus just inferior to the left submandibular salivary gland). There is also mild diffuse retention of activity in the left thyroid gland.

DDx: DDX: Focus of thyroid adenoma in the left superior thyroid bed; thyroid carcinoma; parathyroid hyperplasia
Diagnosis: 1. Parathyroid adenoma in the left superior thyroid bed.
2. Multinodular left thyroid gland
General Discussion:

Full Patient History:
The patient is a 57-year-old woman with hypercalcemia and hyperparathyroidism. The patient had a prior right parathyroidectomy for hyperparathyroidism, as well as right thyroidectomy. The patient is on Synthroid for hypothyroidism.

General Discussion:
Hyperparathyroidism occurs with a frequency of 5 per 10,000. About 80% to 85% of cases of primary hyperparathyroidism are due to single or multiple hyperfunctioning adenomas. Hyperplasia accounts for about 15% of cases and parathyroid carcinomas for about 1-3%

About 80% to 85% of parathyroid adenomas are found adjacent to the thyroid. Ectopic parathyroid adenomas can be found in the anterior or posterior superior mediastinum, within or next to the thymus, along the esophagus, along the carotid sheath, or at the carotid bifurcation. Parathyroid scintigraphy with Tc-99m Sestamibi is commonly part of pre-operative work-up, to help localize adenoma for surgical resection.

Sestamibi (Cardiolite) is an lipophilic cationic isonitrile that passively enters into cellular cytosol and actively concentrate in mitochondria. On parathyroid scintigraphy, Tc-99m Sestamibi initially concentreates in normal thyroid tissue, thyroid adneomas, parathyroid adenomas, and hyperplastic parathyroid glands. Over time (2 hours), there is significant wash-out in the normal thyroid tissue. Thyroid adenomas and hyperplastic parathyroid glands initially have more intense activity than does the thyroid, but they also typically fade with time. Parathyroid adenomas, on the other hand, tend to have more intense initial activity, and retain the radiotracer for longer period of time. Repeat imaging at 2 hours after radiotracer injection can often demonstrate any present parathyroid adenoma, with sensitivity of about 90% in primary hyperparathyroidism. Thyroid cancer and parathyroid carcinoma can also have increased and persistent sestamibi uptake, and should be considered in the differential diagnoses.

In this case, there is initial patchy sestamibi uptake in the left thyroid gland, corresponding to multiple nodules seen on CT (Figure 4), as well as ultrasound (not shown). In addition, there is a small focus of persistent activity in the superior left thyroid bed, corresponding to a nodule on CT (Figure 1, Figure 3). This nodule was proven to be parathyroid adenoma on surgical pathology. Left thyroidectomy showed no cancer. Patient's serum calcium and parathyroid hormone normalized after surgery.

 

References: Essentials of Nuclear Medicine Imaging, Fif-7th Edition, Fred Mettler, MD, Page 96-8
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Additional Details:

Case Number: 241475Owner(s): Collin Liu and Jerold Wallis, Assoc Prof of RadiologyLast Updated: 02-07-2013
Anatomy: Face and Neck   Pathology: Benign Mass, Cyst
Modality: CT, Nuc Med, 3D ReconstructionAccess Level: Readable by all users, writable by NucMed Certifiers
Keywords: parathyroid adenoma, multinoduar thyroid gland, panmACR: 20000.53000, 20000.52000

Case has been viewed 21 times.
Certified by Jerold Wallis on 07-28-2010

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