Case 14-2019: A 44-Year-Old Man with Neck Pain and Swelling

A 44-year-old man was admitted to the hospital because of pain and swelling on the left side of the neck, which developed 12 weeks after placement of an implantable cardioverter–defibrillator. CT revealed a 4-cm heterogeneous soft-tissue mass located deep to the sternocleidomastoid muscle. Additional diagnostic tests were performed.