Ectopic Parathyroid Adenoma: A Case Study




Tijerina, Rudy
Swanson, Lawrence


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Background: Primary hyperparathyroidism is rare in pediatrics, occurring in 1 in every 50,000 children. This case study presents an adolescent with biochemical evidence of primary hyperparathyroidism in the context of a normal neck ultrasound. Case Information: A 15-year-old male with a one-year history of recurrent nephrolithiasis presented for evaluation of hypercalcemia. His initial work-up was notable for elevated PTH, elevated 1,25(OH)2 vitamin D, and low 25OH vitamin D, yielding a diagnosis of primary hyperparathyroidism. However, a neck ultrasound showed no evidence of parathyroid gland abnormalities. He then underwent sestamibi-single photon emission computed tomography/computed tomography (SPECT/CT), which revealed an area of localized uptake in the anterior mediastinum near the aortic arch. He later underwent endoscopic removal of the lesion with no complications. The pathology specimen was consistent with a well circumscribed parathyroid adenoma. Repeat tests performed one month after surgery demonstrated biochemical resolution of the hyperparathyroidism. The patient's pre-surgery labs showed a serum Ca of 11.6 mg/dL (ref 8.9-9.4), an intact PTH of 141 pg/mL (ref 12-71), a 25OHvitD of 17 ng/mL (ref 30-100), and a 1,25(OH)2vitD of 104 pg/mL (ref 19-83). The patient's post-surgery labs showed a serum Ca of 9.3, an intact PTH of 57, a 25OHvitD of 16, and a 1,25(OH)2vitD of 115. Conclusions: The patient's initial laboratory evaluation was consistent with primary hyperparathyroidism, but his neck ultrasound was negative. Because 5 to 26% of children with primary hyperparathyroidism have ectopic parathyroid adenomas, there is value in using broader imaging modalities. Data on the accuracy of various imaging modalities for the detection of ectopic parathyroid adenomas in the pediatric populations is limited. In adult populations, the sensitivity of 99mTechnetium sestamibi scintigraphy for ectopic parathyroid adenomas has ranged from 54% to 100%. Combining functional imaging with detailed anatomic imaging, as with SPECT/CT, aides pre-operative surgical planning and likely further improves diagnostic accuracy. The diagnosis of primary hyperparathyroidism is established by typical findings on blood and urine studies. A negative neck ultrasound does not rule out the presence of a parathyroid adenoma. Scintigraphy and computed tomography are valuable tools in the evaluation of unexplained primary hyperparathyroidism.