Overgrowth of the Hand and Upper Extremity and Associated Syndromes.

The family of overgrowth disorders affecting the hand and upper extremity constitutes a wide spectrum of clinical phenotypes. These conditions and malformations may be isolated to the upper limb or part of an underlying syndrome. When present, these conditions will challenge even the most experienced hand surgeon. Overlapping clinical presentations and a lack of insight into the fundamental pathogenesis that drives overgrowth in these conditions have created confusion in diagnosis and classification, and have also hampered treatment outcome research. In recent years, advances in molecular biology have identified genetic mutations within the affected tissues of overgrowth patients that appear to mediate these disorders. This may elucidate further understanding, classification, and treatment of these conditions. The purpose of this article is to discuss a range of overgrowth conditions, review some of the newer biological insights, and delineate the general treatment principles.