Is erythema toxicum neonatorum a mild self-limited acute cutaneous graft-versus-host-reaction from maternal-to-fetal lymphocyte transfer?

Abstract Erythema toxicum neonatorum (ETN) is a common, self-limited neonate dermatosis affecting worldwide about 50% of newborns—mostly second and later deliveries—irrespective of sex and race. Its etiology still remains obscure: some reaction of the skin of the newborn in adapting to its new environment is the favorite hypothesis to date. A suggested viral or allergic nature could not be confirmed by adequate agent or antigen isolation respectively. In this paper a hypothesis is presented that ETN is a self-limited acute cutaneous graft-versus-host reaction (GVHR) caused in the transiently immunosuppressed newborn by maternal lymphocytes transferred shortly prior to or during delivery.