<unk>  is the common benign cause of mediastinal widening. While it may be associated with exogenous obesity, steroid ingestion, or Cushing's syndrome, these factors often are not present.
Mediastinal lipomatosis
Mediastinal tumor
Tracheal diverticulum
Mediastinal mass
Mediastinal hematoma
Pulmonary cystic lymphangiectasis
Peritonsillar abscess
Adenoid hypertrophy