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.
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.
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.
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.