Sucking pads (sucking calluses) of the lips in neonates: a manifestation of transient leukoedema.

The clinical and histologic features of sucking pads in neonates are clearly different from sucking blisters and leukoedema, both of which may also be present in neonates. We propose that the condition is due to a combination of intracellular edema and hyperkeratosis. Perhaps the alternative term of sucking calluses is more appropriate. The intracellular edema is ascribed to passive diffusion of fluid, presumably saliva, into the cells, while the hyperkeratosis is regarded as an adaptive phenomenon to friction during sucking.