Ectopic primary hyperparathyroidism.

OBJECTIVE: To review an unusual case of ectopic primary hyperparathyroidism. METHODS: We present a case report, including longitudinal results of laboratory studies, and comment on the difficulties with standard imaging techniques, interpretation of parathyroid pathologic findings, and use of invasive localization techniques. RESULTS: A 74-year-old woman underwent repeated assessments because of hypercalcemia. When standard parathyroid 99mTc sestamibi imaging was negative for adenoma and initial surgical exploration of the neck and removal of 3' parathyroid glands were unsuccessful in correcting the hyperparathyroidism, the ectopic adenoma was ultimately localized on an extended-field 99mTc sestamibi scan in the region of the right dome of the diaphragm. The localization was confirmed by selective venous sampling and angiography. The ectopic parathyroid adenoma was embolized, and 1 month later, the serum calcium level was normal. CONCLUSION: Ectopic lesions should be considered when standard imaging techniques are nonrevealing and standard neck exploration fails to disclose a parathyroid adenoma in a patient with persistent hypercalcemia. Selective venous sampling and angiography can assist in localization of ectopic parathyroid adenomas.