Pectus carinatum
Pectus carinatum, (L carinatus, equiv. to carin(a) keel), also called pigeon chest, is a deformity of the chest characterized by a protrusion of the sternum and ribs. It is the opposite of pectus excavatum.

# Causes
Pectus carinatum is an overgrowth of cartilage causing the sternum to protrude forward. It occurs in 3 different ways.
The least common way is post surgically after open heart surgery. Sometimes the sternum does not heal flat and there is a protrusion of the sternum.
The second most common is from birth. It is evident in newborns as a rounded chest and as they reach 2 or 3 years old the sternum begins to grow outwardly even more.
The most common occurrence for pectus carinatum seems to be in the 11-14 year old pubertal male undergoing a growth spurt. Some parents report that their child's pectus seemingly popped up 'overnight'.
It may occur as a solitary congenital abnormality or in association with other genetic disorders or syndromes : Marfan syndrome, Morquio syndrome, Noonan syndrome,  Trisomy 18, Trisomy 21, homocystinuria, osteogenesis imperfecta, multiple lentigines syndrome, Sly syndrome and Scoliosis.
In about 25% of cases of pectus carinatum, the patient has a family member with the condition.

# Epidemiology
Pectus deformities are common; about 1 in 400 people have a pectus disorder.
Pectus carinatum is rarer than pectus excavatum, another pectus disorder, occurring in only about 20% of people with pectus deformities.  About four out of five patients are males.

# Symptoms
People with pectus carinatum usually develop normal hearts and lungs, but the deformity may prevent these from functioning optimally. In moderate to severe cases of pectus carinatum, the chest wall is rigidly held in an outward position. Thus, respirations are inefficient and the individual needs to use the diaphragm and accessory muscles for respiration, rather than normal chest muscles, during strenuous exercise. This negatively affects gas exchange and causes a decrease in stamina. Children with pectus deformities often tire sooner than their peers, due to shortness of breath and fatigue. Commonly concurrent is mild to moderate asthma.
Some children with pectus carinatum also have scoliosis (curvature of the spine). Some have mitral valve prolapse, a condition in which the mitral valve functions abnormally. Connective tissue disorders involving structural abnormalities of the major blood vessels and heart valves are also seen. Although rarely seen, some children have other connective tissue disorders, including arthritis, visual impairment and healing impairment.
Apart from the possible physiologic consequences, pectus deformities can have a significant psychologic impact. Some people, especially those with milder cases, live happily with pectus carinatum. For others, though, the shape of the chest can damage their self-image and confidence, possibly disrupting connections and causing them to feel uncomfortable throughout adolescence and adulthood. As the child grows older, especially if male, bodybuilding techniques may be useful for balancing visual impact.

# Prognosis
Pectus deformities usually become more severe during adolescent growth years and may worsen throughout adult life. The secondary effects, such as scoliosis and cardiovascular and pulmonary conditions, may worsen with advancing age.
Body building exercises (often attempted to cover the defect with pectoral muscles) will not alter the ribs and cartilage of the chest wall, and are generally considered not harmful.
Fortunately, most insurance companies no longer consider chest wall deformities like pectus carinatum to be purely cosmetic conditions. While the psychologic impact of any deformity is real and must be addressed, the physiological concerns must take precedence. The possibility of lifelong cardiopulmonary difficulties is serious enough to warrant a visit to a thoracic surgeon.

# Treatment

## External bracing technique
In children up to age 16 who have mild to moderate pectus carinatum and are motivated to avoid surgery, the use of a custom-fitted chest-wall brace pushing directly on the sternum produces excellent outcomes. Willingness to wear the brace as required is essential for the success of this treatment approach. The brace works in much the same way as orthodontics (braces) works to correct the alignment of teeth. It consists of front and back compression plates that are anchored to aluminum bars. These bars are bound together by an adjustable leather strap on each side. This device is easily hidden under clothing and must be worn over a T-shirt for 14 to 16 hours a day for a minimum of two years or until full height is reached. Children are taught how to tighten the straps of the brace so to gradually increase the pressure applied to their chest. Parents learn how to check to see if adequate pressure is being applied. Pediatric surgeons monitor progress at office visits every six months.

## Surgery
In children who are not candidates for bracing, surgery may be necessary to restore normal chest contour. Open surgery in boys is performed through a horizontal incision on the anterior chest wall, usually just below the nipple area. In girls, this incision is placed to coincide with the lower breast margins when possible. The lower four to five cartilages that are abnormal are removed, leaving the perichondrium (the lining that envelops the outer portion of rib cartilage). This allows the cartilage to regrow in its new position. The sternum is surgically fractured and placed in the correct position. The incision is usually closed with internal sutures that minimize scarring.
The length of hospital stay following surgery is typically three to four days, but children often experience some discomfort for several weeks. For several days following surgery pain can be well controlled by epidural analgesia catheters or intravenous narcotics. Milder pain is managed with oral medication. Although minor complications sometimes occur, these are quite easy to treat. Cosmetic and physical outcomes in children who have undergone surgery in mid-childhood or early adolescence are generally excellent.

## Non-surgical options
After adolescence, some males use bodybuilding as a means to hide their deformity, where women find that their breasts, if large enough, serve the same purpose. Some plastic surgeons perform breast augmentation to disguise mild to moderate cases in women. Bodybuilding is suggested for people with symmetrical pectus carinatum.