IgG4 is an immunoglobulin subtype that has many physiologic and morphologic peculiarities. In cutaneous pathology, IgG4 has been related to the pathogenesis of many diseases. Moreover, in the recent years, new IgG4-related diseases have been described. Since some involve the skin, either primarily or as part of their systemic manifestations, we have tried to briefly examine some of the cutaneous conditions related to IgG4.