Poland anomaly is an underdevelopment or absence of the chest muscle on one side of the body and webbing of the fingers of the hand on the same side.
What is Poland anomaly?
Named after Sir Alfred Poland, Poland anomaly (PA) is described as an underdevelopment or absence of the chest muscle (pectoralis) on one side of the body and webbing of the fingers (cutaneous syndactyly) of the hand on the same side (ipsilateral hand). Sometimes referred to as "Poland syndrome," it is an uncommon condition present at birth (congenital). For people born with PA, the breastbone portion (sternal) of the pectoralis is also missing.
Since the severity of Poland anomaly differs from person to person, it is not often diagnosed or reported. Sometimes, a person does not realize they have the condition until puberty, when lopsided (asymmetrical) growth makes it more obvious. The incidence, therefore, is difficult to determine. Current estimates are between one in 10,000 to one in 100,000 births. Poland anomaly is more common in boys than girls, and the right side is affected twice as often as the left. The reasons for these differences are unknown.
What are the associated features of Poland anomaly?
People born with Poland anomaly have several physical and cosmetic disabilities, which can be treated if correctly diagnosed. Although severity and associated features vary from patient to patient, there are some common characteristics of this condition:
- Absence (aplasia) of some of the chest (pectoralis) muscles.
- The end of the main chest muscle, where it attaches to the breastbone, is usually missing.
- The nipple, including the darkened area around it (areola) is underdeveloped or missing. And in females, this may extend to the breast and underlying tissues.
- Abnormally short, webbed fingers (syndactyly).
- Often, the armpit (axillary) hair is missing.
- The skin in the area is underdeveloped (hypoplastic) with a thinned subcutaneous fat layer.
- The upper rib cage can be underdeveloped or missing. Sometimes, such abnormal development extends to the shoulder blade or the bones of the arm.
- Rarely, spine or kidney problems may also be present.
All these symptoms occur on one side of the body (unilateral). Also, it is important to note that Poland anomaly does not typically affect intelligence.
What causes Poland anomaly?
The cause of Poland anomaly is unknown. Most evidence supports the idea that something happens during the sixth week of fetal development (gestation). This event most likely involves the vascular (blood and lymph) system. Speculations include:
- An interruption of the embryonic blood supply of the arteries that lie under the collarbone (subclavian arteries). This could be caused by the forward growth of the ribs reducing the flow of blood.
- A malformation of the subclavian arteries causes a reduced amount of blood delivered to the developing tissues on one side of the body.
How is Poland anomaly diagnosed and treated?
Poland anomaly can be detected as early as birth and as late as adolescence, depending on how severe it is. PA can be detected through thorough clinical evaluation and from a variety of specialized tests. Tests may include advanced magnetic resonance imaging (MRI) techniques, computerized tomography (CT) scans and X-Rays. CT scans help determine the extent to which the muscles may be affected, by showing cross-sectional images of particular structures within the body. X-Rays can help identify and characterize any specific abnormality in the hand, forearm, ribs and/or shoulder blades.
Under mild circumstances, a person may not know he or she has PA until puberty. Puberty makes the difference between the two sides of the body more obvious. This is especially true for girls, who may notice a difference in the development of the breasts. When the anomaly is more severe, hand and arm abnormalities make the disorder more apparent early in life.
The most viable treatment for PA is reconstructive surgery. Existing chest muscles are used to rebuild the chest. Muscle can be taken from other parts of the body, for instances where there is not enough chest muscle for rebuilding. For males with PA, reconstructive surgery can be done as early as age 13. For females, surgery may have to be postponed until breast development is complete. Reconstructive surgery can be helpful for the psychological development of teenagers, who are especially aware of physical differences. However, if surgery is performed too early, while the individual is growing, asymmetry can result or be made greater than before. For females, reconstructive surgery may be performed to correct the different sizes of the two breasts. Differences in the nipple and areola can be treated by therapeutic tattooing. This treatment is intended to give the breast the appearance of a nipple and areola.
What do we know about heredity and Poland anomaly?
Poland anomaly is rarely inherited and generally sporadic. Though instances of patients with PA are isolated within the family, familial occurrence has been observed. The exact mode of transmission has not yet been confirmed. Familial occurences include: transmission from parent to offspring; in siblings born to unaffected parents; and with the presence of PA in distant family members such as cousins. Some researchers suggest that familial PA may stem from inherited susceptibility to events such as interruption of blood flow that may predispose a person to the anomaly.