Squamous cell carcinoma of the lung mimicking an ectopic mediastinal parathyroid adenoma demonstrated by Tc-99m sestamibi in a hypercalcemic patient

Hypercalcemia was an incidental finding of a physical checkup in a 63- year-old woman. Laboratory data showed hypercalcemia, low serum immunoreactive parathyroid hormone level, and high serum c-terminal parathyroid hormone-related protein level. A Tc-99m sestamibi (MIBI) scan was performed to search for any hypercalcemia-related malignancy. An area of abnormal accumulation of MIBI in the right superior mediastinal region was noted. Because malignancy in the right superior mediastinum seemed certain, she had a CT. The results of the chest CT scan revealed an enlarged lymph node in the right upper mediastinum. Cytologic analysis during bronchoscopy showed squamous cell carcinoma of the lung.