Brown adipose tissue in a newborn.

ing 2605 g was found to have bilateral supraclavicular masses at 13 days of life. He had persistent pulmonary hypertension of the newborn and thrombocytopenia. Delivery was by cesarean section for nonreassuring fetal status, and Apgar scores were 5 at 1 minute and 8 at 5 minutes. Initial radiographs of the chest demonstrated abnormal supraclavicular fullness bilaterally (Figure 1), and soft tissue neck sonography demonstrated hyperechoic masses involving the supraclavicular region bilaterally with internal vascular flow and hyperechoic bands. Differential considerations included lipoma, lipofibroma, hemangioma, and lymphangioma. Computed tomography (CT) of the chest and neck were subsequently performed to evaluate the masses for the presence of fat (Figure 2). Hypodense masses were demonstrated within the axilla, supraclavicular fossa, and lower neck bilaterally. Peripheral nodular enhancement was present within the axillae. Differential considerations included mixed venolymphatic malformation, hemangioma, and lymphoproliferative disorder. There was no evidence of lymphadenopathy within the chest or neck. Subsequent magnetic resonance imaging (MRI) of the chest demonstrated symmetric and confluent soft tissue extending from Radiology Report