Macrodactyly simplex congenita. A case series and considerations of differential diagnosis and aetiology

Macrodactyly simplex congenita (MSC) is a rare congenital anomaly comprising some 10% of cases of isolated congenital macrodactyly. The essential elements in MSC are mentioned and a differential diagnosis from other forms of enlarged digits is given, in the light of the natural history of the condition. The distinction is shown to have practical therapeutic implications. The causation is discussed and a hypothesis advanced of a possible somatic mutation in an inhibitory chalone receptor allowing the switch-on of unimpeded local growth.