The characteristic histologic change seen at 2 h in the Rumpel-Leede (Hess) test is, in addition to focal hemorrhage in the upper dermis, a perivascular lymphocyte infiltrate with focal areas of lymphocytic epidermal invasion. The histologic findings, even with the liquefaction degeneration, are similar to those of purpura simplex and indicate that, early in many forms of vasopermeability, the lymphocyte may be a primary inflammatory cell.