As the extent of Poland Syndrome is so variable, nobody is entirely sure how common the condition is, but it is most likely to occur in about 1 in 25,000 people. The exact cause is also not known for sure, but it is likely to be due to a temporary blockage of the blood supply of the arm during development. As a result of that lack of blood supply, the muscles connecting the chest to the arm do not develop as they should, and the arm and hand itself can also not develop well. It is three times as common in boys as in girls, and is more common on the right side than on the left. The condition was first described by Alfred Poland, in London, in 1841.
There are no distinct types of Poland Syndrome, as there is a continuous spectrum of severity of the condition and its impact on patients. It is, however, helpful to consider Poland Syndrome in terms of what it affects. In almost everyone with the condition, there is underdevelopment of the main ‘pec’ muscle, the pectoralis major. This muscle has two parts: one that connects the clavicle or collar bone to the upper arm and another that connects the sternum or breast bone to the upper arm. The most common developmental problem in Poland Syndrome is that the sternal head connecting the breast bone to the upper arm is missing. This has the effect of giving an asymmetry in the upper chest, where this muscle would normally be, but this muscle is also responsible for giving the shape of the fold of skin separating the upper chest from the armpit, the anterior axillary fold. As a result of this missing fold, the definition of the side of the upper chest is altered, and this is a common complaint among patients with Poland Syndrome.
In female patients, there is often underdevelopment of the breast on the affected side, which is the most common reason that patients with Poland Syndrome consult a Plastic Surgeon. With increasing severity of the condition, the other part of the pectoralis major muscle can be missing and, in the more severe cases there can be other missing muscles between the chest or back and the arm, the skin and fat over the chest can be thin and patients can have a missing shoulder blade or missing ribs which can lead to breathing difficulties.
The hand and arm can be underdeveloped, not only in terms of the length of the upper arm, forearm, hand or fingers, but also because the fingers can fail to separate well. Although a wide variety of hand problems can be found with Poland Syndrome, the most common is brachysyndactyly in which the fingers are short and partially joined together.
Poland Syndrome is most commonly the only problem affecting a patient, but it can be found together with Dextrocardia, in which the heart lies on the right side of the body rather than the left, Moebius Syndrome, or underdevelopment of the kidneys or the feet.
A child can be affected by Poland Syndrome in various ways depending on the degree of severity of the condition. Some children have only a mild asymmetry of their chest and may not even know they have Poland Syndrome. Others, especially girls, can be unaffected until they reach puberty at which point they notice that one breast fails to keep up with the development of the other or fails to develop entirely. In the most severely affected patients, diagnosis is usually soon after birth and may require early treatment for the underdeveloped hand or to correct breathing difficulties due to the incomplete rib cage.
There is no lab test for Poland Syndrome, and the diagnosis is made by a doctor based on an assessment and physical examination of the patient. The doctor will look and feel for the different parts of the pectoralis major muscle and then also examine for other signs of the condition in the chest, back, arm and hand.
Signs to look for would include asymmetry between the two sides of your chest, asymmetry in breast development between the two sides in female patients, a difference between your two sides in the skin fold between the side of the chest and the armpit and any difference between your hands.