Cutaneous and systemic plasmacytosis is a rare disorder observed mainly in Japanese that features an infiltration of mature plasma cells in various organ systems. In addition to the skin, lymph nodes and bone marrow are regularly affected. Laboratory tests show a polyclonal hypergammaglobulinemia. The cutaneous morphology is characterized by red to dark brown macules, papules and plaques a few centimeters in diameter, usually distributed symmetrically on the face, neck and back. Etiology and pathogenesis are not known. It is speculated that a reactive dysfunction of plasma cells may be triggered by various stimuli, such as interleukin 6. Treatment of cutaneous and systemic plasmacytosis is difficult. A standardized treatment concept does not yet exist. Topical corticosteroids and calcineurin inhibitors are mainly used.