Pathology of macrodactyly.

Macrodactyly is an unusual congenital anomaly in which there is hamartomatous proliferation of the soft tissue of the affected digit. It is usually present at birth or recognized during adolescence. Eleven cases are presented. All showed abnormal accumulation of adipose tissue in the affected digits. In five cases, prominent endoneural and perineural fibrosis was noted. Two cases also demonstrated focal neural and vascular proliferation. This is an unusual finding in macrodactyly and may be a part of the abnormal hamartomatous proliferation that is observed in this condition. None of the patients had clinical evidence of neurofibromatosis. One patient had the Proteus syndrome.