(i.e., Kawasaki disease) often have cervical lymphadenopathy and, on rare occasions, have active life-threatening vasculitis of the coronary vessels Although neck tumors generally grow outward, in children, they may become large enough to encroach on vital structures Lymphoma, an uncommon but important cause of neck mass, is usually associated with painless enlargement (often of supraclavicular nodes) that occurs over several weeks in the older school-aged children Anterior mediastinal node involvement creates airway collapse in the supine position secondary to tracheal compression This may manifest as orthopnea Cystic hygromas and hemangiomas occasionally enlarge sufficiently enough to interfere with feeding or to obstruct the airway Other neoplasms, such as rhabdomyosarcoma, leukemia, neuroblastoma, and histiocytosis X, are life threatening because of local invasion and metabolic and hematologic effects Table 48.1 lists disorders that constitute true emergencies because of local pressure on vital structures or because of systemic toxicity TABLE 48.1 LIFE-THREATENING CAUSES OF NECK MASS Hematoma secondary to trauma Cervical spine injury Vascular compromise or acute bleeding Late arteriovenous fistula Subcutaneous emphysema with associated airway or pulmonary injury Local hypersensitivity reaction (sting/bite) with airway edema Airway compromise with epiglottitis, peritonsillar abscess, or infection of floor of mouth or retropharyngeal space (with adenopathy) Bacteremia/sepsis associated with local infection of a cyst (cystic hygroma, thyroglossal, or branchial cleft cyst) Non-Hodgkin lymphoma with mediastinal mass and airway compromise Thyroid storm Mucocutaneous lymph node syndrome with coronary vasculitis (Kawasaki disease) Tumor—leukemia, lymphoma, rhabdomyosarcoma, histiocytosis X Lemierre syndrome Child With Neck Mass and No Distress