What Is Poland Syndrome?

Poland syndrome, also known as Poland sequence or Poland anomaly, is characterized by pectoralis major muscle hypoplasia or aplasia combined with symbrachydactyly (syndactyly). Clinical manifestations primarily involve the thorax and upper limbs; it occurs more frequently in males and is typically unilateral, with bilateral involvement being extremely rare. In its mildest form, the condition involves only absence of the sternocostal head of the pectoralis major muscle and syndactyly between the third and fourth fingers. In severe cases, in addition to complete absence of the pectoralis major muscle, other structures may be affected—including the underlying pectoralis minor, serratus anterior, intercostal muscles, and even adjacent portions of the latissimus dorsi, external oblique muscle, and even parts of the ribs and costal cartilages in the anterior chest wall.