A case-control study addressing the population of epidermal and dermal inflammatory infiltrate including neural milieu in primary prurigo nodularis using S-100 and toluidine blue stain and its therapeutic implications.

We can infer that the epidermal and dermal pathology in PN is related to the infiltrate of lymphocytes, mast cells, and neural hyperplasia which perpetuate the pathogenesis by triggering the itch-inflammation cycle. Thus, apart from immunosuppressive agents that target lymphocytes and their cytokines, therapy targeted at mast cells and neural proliferation may be needed to treat prurigo nodularis.