Parathyroid hyperplasia shown on (99m)Tc-HYNIC-TOC scan.

A Tc-99m-HYNIC-TOC scintigraphy was performed on a 68-year-old patient with hypercalcemia and borderline hypophosphatemia to assess the source of suspected tumor-induced osteomalacia. The images revealed increased activity in the upper mediastinum and focal activity in the pancreas. The lesion in the upper mediastinum was subsequently proven pathologically as parathyroid hyperplasia in a patient with multiple endocrine neoplasia type 1 (MEN-1 syndrome).