The pathology of clubbing: vascular changes in the nail bed.

In this study post-mortem angiograms were prepared from both normal and clubbed hands and attempts were made to estimate the size of the vascular bed in the terminal parts of each finger. Representative cases were also examined histologically. There were no differences between the groups. The increase in blood flow in clubbing is the result of vasodilatation rather than hyperplasia of vessels in the nail bed.