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 Diagnosis
 Parathyroid Adenoma

Case 4

                                       Contributors

                                                 Dr.Ambika Sunil Gayad                                                            Dr. Susheel

 Radiological Findings, Disease course, and Management

 

 High Resolution Ultrasound examination of the neck

 

 

 

 

 

 

 

 

 

   

 

 

 

 

 

 

 

 

Findings

  • well-circumscribed, oval shaped hypoechoic lesion approximately measuring 12 x 6 mm with significant internal vascularity near the inferior pole of left lobe of thyroid gland

  • Thyroid gland shows coarse echotexture with diffuse increase in vascularity. No focal lesions seen in thyroid gland. No cystic lesions /   micro-calcification seen

  • No evidence of enlarged cervical lymph nodes seen.

 

Impression

   Coarse echotexture of thyroid gland with increased vascularity and          a well-defined hypoechoic lesion near the inferior pole of left lobe of        thyroid gland --- could represent Parathyroid adenoma  

 

Nuclear Parathyroid study

 

               

                                                  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Findings

  • Tracer uptake in the thyroid which washes away with time

  • Persistent focal tracer uptake in the lower pole of the left lobe of thyroid

Impression

  • Scan features are suggestive of a functioning parathyroid adenoma in the region of the lower pole of the left lobe of the thyroid

 

Discussion

   Background

  • Parathyroid adenomas are benign tumours of the parathyroid glands

  • most common cause of primary hyperparathyroidism.

  • Patients present with primary hyperparathyroidism: elevated serum calcium levels and elevated serum parathyroid hormone levels resulting in multisystem effects like osteoporosis, renal calculi, constipation, peptic ulcers, mental changes, fatigue, and depression.

  • usually oval or bean-shaped, but larger adenomas can be multilobulated. The vast majority (up to 87% 2) of adenomas occur as solitary lesions.

  • Location: majority of parathyroid adenomas are juxtathyroid immediately posterior or inferior to the thyroid gland.
    Superior gland parathyroid adenoma may fall posteriorly in the tracheo-     oesophageal groove or para-oesophageal location or even fall inferior as     far as the mediastinum. Up to 5% of parathyroid adenomas can occur in     ectopic locations that include mediastinum, retropharygneal,carotid           sheath, intrathyroidal
  • Serology: Parathyroid hormone levels are usually elevated (usual normal reference range 1.6-6.9 pmol/L or 10 to 55 pg/mL).

 Diagnosis

 Imaging findings

 Ultrasound

 Greyscale

  • homogeneously hypoechoic to the overlying thyroid gland with an echogenic thyroid capsule separating the thyroid and parathyroid 

 Doppler ultrasound

  • may show a characteristic extrathyroidal feeding vessel (typically a branch off the inferior thyroidal artery which enters the parathyroid gland at one of the poles 

  • Internal vascularity has a peripheral distribution giving a characteristic arc or rim of vascularity 

 
 Nuclear medicine

  • useful for localising the lesion when the site is not known

  • Shows increased uptake with agents such as technetium (Tc) 99m Sestamibi (MIBI) (commonly used agent) and Tc-99m tetrofosmin.

 
 CT

4D-CT has emerged as valuable modality in minimally invasive parathyroidectomy a surgery that requires precise localization with anatomical detail and a confident diagnosis of parathyroid adenoma

Enhancement on 4D-CT

On 4D-CT parathyroid adenomas typically demonstrate intense enhancement on arterial phase, washout of contrast on delayed phase and low attenuation on non-contrast imaging 12.

Secondary signs include 14:

  • the polar vessel which represents an enlarged feeding artery or draining vein to the hypervascular parathyroid adenoma

  • a larger lesion size increases the confidence of diagnosis

  • parathyroid adenomas can also have cystic change

 
 MRI

MRI is infrequently utilized in initial work up because of lower spatial resolution and artifacts. Adenomas can show variable signal intensity on MRI. Reported signal characteristics include:

  • T1

    • typically intermediate to low signal

    • subacute haemorrhage can cause high signal intensity 6

    • fibrosis or old haemorrhage can cause low signal intensity 6

  • T2

    • typically hyperintense

    • subacute haemorrhage can cause high signal intensity 6

    • fibrosis or old haemorrhage can cause low signal intensity 6

Since most lesions demonstrate high T2 signal intensity, the addition of contrast for MR scanning does not significantly increase detection.

 

 Differential diagnosis

 

 Treatment and prognosis

  • Surgery is successful in treating primary hyperparathyroidism caused by parathyroid adenomas in 95-98% of cases

 

 References

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