Abnormal cutaneous topobiology: the molecular basis for dermatopathologic mononuclear cell patterns in inflammatory skin disease.

Because of the identification and characterization of various adhesion molecules (lymphocyte function associated antigen-1, intercellular adhesion molecule-1), chemotactic factors (interleukin-8, monocyte chemotactic/activating factor), and their modulatory cytokines (gamma interferon, tumor necrosis factor), it is possible to begin to ascribe specific molecules to cutaneous cellular reaction patterns. The abnormal topobiology, or altered spatial distribution, of mononuclear cells, which gives rise to disease-specific patterns, was described in molecular terms. A large number of diverse skin diseases were classified into six different groups, with each group highlighting distinctive cell types, adhesion molecules, chemotactic factors, and cytokines. The diseases within each group, which share functional anatomical reaction zones, were postulated to share common pathophysiologic pathways. Thus, it is now possible, as one scans the microscopic field, to look past the static images of red- and blue-stained cells and appreciate a dynamic and detailed medley of molecularly defined events emanating from the eyepiece.