Langerhans cell histiocytosis: an unusual cause of vesicular rashes in a neonate.

The skin manifestations of Langerhans cell histiocytosis (LCH) in the neonate have a heterogenous presentation and can mimic other causes of neonatal rashes. We report an uncommon case of LCH in a term female neonate presenting with non-specific papules and vesicles from the first day of life. There was a maternal history of genital herpes simplex virus (HSV) infection in the third trimester. Blood, cerebrospinal fluid, surface swabs and vesicular fluid were negative for HSV by PCR, and a skin biopsy confirmed the diagnosis of LCH. Further investigations for systemic involvement returned negative. Our case emphasises the variable and non-specific presentation of neonatal cutaneous LCH, which can progress to or be part of multisystem disease.