The case illustrates the radiological features of hyperparathyroidism including giant cell tumors at the iliac bones, osteomalacia of the examined bones, stress fractures of the inferior pubic rami, bilateral erosive changes of the articular surfaces of both sacroiliac joints, subperiosteal resorption of the medial aspect of the left femoral neck and erosive changes of the medial sternal heads.

99mTc sestamibi (99mTc-MIBI) imaging gave a false negative study and failed to localize the parathyroid adenoma.

However, CT and MRI of the neck showed an irregular-shaped lesion at the suprasternal region showing mixed fatty and solid texture.

The patient later underwent surgical resection of the suprasternal parathyroid tumor and the pathological diagnosis was parathyroid adenoma.

False negative 99mTc sestamibi results might be secondary to small tumor size, cystic components, multiglandular disease, and the site of parathyroid adenoma. In this case, other imaging modalities such as 4D CT, US, MRI, or even venous sampling might help to localize parathyroid adenomas.