In what condition would a patient exhibit a "barrel chest" deformity?

A "barrel chest" deformity is typically associated with chronic obstructive pulmonary disease (COPD), particularly emphysema, which is a common form of COPD. This deformity occurs due to the over-inflation of the lungs, leading to an increased anterior-posterior diameter of the chest. The hyperinflation arises from the destruction of the alveoli, causing air trapping during exhalation. As a result, the normal rib cage configuration is altered, resulting in the rounded appearance characteristic of a barrel chest.

In cases of asthma, while patients may experience difficulty breathing, the physical manifestation of a barrel chest is less common. Pneumonia typically presents with symptoms like fever, cough, and chest pain, but does not cause the chronic structural changes seen in COPD. Lung cancer may lead to other symptoms and complications, but it is not defined by the barrel chest appearance specifically associated with chronic lung hyperinflation.