Correct answer:

(1) In the lumen: foreign body.
(2) In the wall: congenital atresia; inflammatory stricture – secondary to reflux oesophagitis; caustic stricture; achalasia; Plummer-Vinson syndrome with oesophageal web; pharyngeal pouch; Schatzki ring; tumour of oesophagus or cardia; systemic sclerosis (scleroderma).
(3) Outside the wall: bronchial carcinoma; retrosternal goitre; aneurysm of the thoracic aorta; node – pressure from an enlarged lymph node.