Increased 99mTc-MAA Uptake in Supraclavicular Brown Adipose Tissue in a Pediatric Patient With Hereditary Hemorrhagic Telangiectasia

A 10-year-old boy underwent a whole-body scan using 99mTc-labeled macroaggregated albumin (99mTc-MAA) to evaluate the underlying cause of hypoxemia. The scan demonstrated abnormally increased 99mTc-MAA uptake in the brain, thyroid, kidneys, and metaphyses of long bones—findings consistent with significant intrapulmonary shunting. Subsequent whole-exome sequencing confirmed a diagnosis of hereditary hemorrhagic telangiectasia. Notably, markedly increased 99mTc-MAA uptake was also observed in the supraclavicular brown adipose tissue.