Poland syndrome: description of an atypical variant.

Poland syndrome comprises a unilateral absence of the large pectoral muscle, ipsilateral symbrachydactyly, and occasionally other malformations of the anterior chest wall and breast. The condition is more frequent among males, and usually occurs on the right hemithorax in the unilateral form. The syndrome is believed to be caused by a genetic disorder that reduces the embryonal circulation in the interior chest artery: the stronger the interaction, the more severe the pathology. This article analyzes an unusual pathologic case in which the 17-year-old patient lacked the large pectoral muscle on the left side, but showed no arterial alteration. This case raises questions as to the true pathogenesis of this syndrome.