WHOLE-BODY SESTAMIBI SCAN USEFULNESS AND DETECTION OF MULTIPLE BROWN TUMOURS

Abstract

INTRODUCTION
Radionuclide sestamibi scan with standard neck and mediastinum acquisition is an important modality to localise parathyroid lesion. Hyperparathyroidism can be associated with brown tumour or lytic bone lesion arising from excess osteoclast activity. Although bone scan is commonly used to evaluate brown tumour, parathyroid scan with whole-body image acquisition may also be deployed. We present a rare case of primary hyperparathyroidism in young adult complicated with brown tumour to highlight the usefulness of whole-body sestamibi scan.

RESULTS
30-year-old male with no prior comorbidity or family history of endocrine disorders had presented with nontraumatic right forearm and right mid shin swellings for two months in late 2020. These swellings caused some degree of discomfort, but he was otherwise asymptomatic. Radiographs revealed lucent bone lesions. He was then further investigated and found to have raised serum alkaline phosphatase (674 U/L), calcium (2.95 mmol/L) and parathyroid hormone levels (50.4 pmol/L). His renal profile and remaining routine blood investigations were unremarkable. Diagnosis of primary hyperparathyroidism was made, and he was referred for scintigraphy localisation of hyperfunctioning parathyroid gland. Single tracer sestamibi scan (9.3.2021) was performed using standard acquisition followed by planar whole-body imaging at delayed phase. Supplementary thorax and lower limb single photon emission computed tomography/ computerised tomography (SPECT/CT) was also done. A parathyroid adenoma is seen at inferior pole of right thyroid lobe associated with multiple sestamibi-avid lytic lesions suggestive of brown tumours involving proximal right radius, right anterolateral 8th rib, distal third of left femur, proximal and distal end of left tibia, and mid shaft of right tibia.

CONCLUSION
Whole-body sestamibi scan appears not only useful to identify hyperfunctioning parathyroid lesion, but concurrently evaluate multiple brown tumours in a young adult with primary hyperparathyroidism. Information obtained may facilitate overall management including treatment of potential brown tumour related morbidities.