Congenital absence of the pectoral muscles. A review of twenty-five patients.

Twenty-five patients with unilateral partial absence of the pectoral major muscle were reviewed to determine the presence of fetal insult, associated anomalies, neoplasia, and prognosis. Fifteen had ipsilateral synbrachydactyly (the Poland Anomaly) which varied in severity from minimal findings to nearly complete absence of the hand. The pattern of abnormality was remarkably uniform with maximal involvement of the midhand and least involvement of the thumb and small finger. The etiology of this condition remains unknown although fetal insult is suggested in some cases. Although reports in the literature suggest a relationship with childhood leukemia, no malignancies were found in these children. None was found to have serious associated anomalies and all were judged to be of normal intelligence, suggesting a generally good prognosis.