Mediastinal Remnant Thymic Tissue Misdiagnosed as Ectopic Parathyroid Hyperplasia in Secondary Hyperparathyroidism.

A 56-year-old woman with secondary hyperparathyroidism was referred for preoperative localization of hyperfunctioning parathyroid lesions. Tc-MIBI dual-phase and SPECT/CT parathyroid scan showed multiple focal activities behind the thyroid and in the anterior mediastinum, diagnosed as parathyroid hyperplasia. However, the histopathological findings proved them to be hyperplastic parathyroid glands and remnant thymic tissue after parathyroidectomy and unnecessary thoracotomy, respectively.