Pectus excavatum is a structural deformity of the anterior thoracic wall in which the sternum and rib cage are shaped abnormally. This produces a caved-in or sunken appearance of the chest. It can either be present at birth or develop after puberty.

Pectus excavatum can impair cardiac and respiratory function and cause pain in the chest and back.

People with the condition may experience severe negative psychosocial effects and avoid activities that expose the chest.

Pectus excavatum is from Latin meaning hollowed chest. It is sometimes referred to as sunken chest syndrome, cobbler's chest or funnel chest.

The hallmark of the condition is a sunken appearance of the sternum. The most common form is a cup-shaped concavity, involving the lower end of the sternum; a broader concavity involving the upper costal cartilages is possible. The lower-most ribs may protrude ("flared ribs"). Pectus excavatum defects may be symmetric or asymmetric.

People may also experience chest and back pain, which is usually of musculoskeletal origin.

In mild cases, cardiorespiratory function is normal, although the heart can be displaced and/or rotated. In severe cases, the right atrium may be compressed, mitral valve prolapse may be present, and physical capability may be limited due to base lung capacity being decreased.

Psychological symptoms manifest with feelings of embarrassment, social anxiety, shame, limited capacity for activities and communication, negativity, intolerance, frustration, and even depression.