Langerhans cell histiocytosis (LCH) is a clonal proliferation of pathologic cells with the characteristics of Langerhans cells. It has a broad spectrum of manifestations, ranging from a benign single-system presentation to a severe multi-system disease.
We report a case of a generally well two-day old boy who was referred to our service for multiple papules and vesicles noted at birth that rapidly progressed into erythematous papules and macules, some topped with yellowish and hemorrhagic crusts. Initial assessment by Pediatrics was possible herpes simplex virus or varicella infection, which was supported by a positive Tzanck smear. However, pertinent laboratory examinations were negative. Skin biopsy showed proliferation of large epithelioid histiocytes with large vacuolar reniform nuclei in the dermis. Immunohistochemical staining with CD1A was positive. The results were consistent with LCH. The early onset of skin lesions, lack of systemic involvement, and rapid improvement, point to a diagnosis of a single system LCH or the congenital self-healing variant. A positive Tzanck smear in a case of LCH has previously been reported in literature and is attributed to histiocytes viewed on examination. Upon discharge, the remaining lesions were light brown macules. Monitoring was done on an outpatient basis.
LCH is diagnosed based on the histopathologic evaluation of involved skin tissue interpreted within the clinical context. It is confirmed by appropriate positive immunohistochemical staining. Relevant diagnostic examinations are needed to rule in a diagnosis of the congenital self-healing variant. While it is typically benign, monitoring is still warranted given the possibility of relapse or progression.

Human ; Male ; Infant Newborn ; Chickenpox ; Dermis ; Histiocytes ; Histiocytosis, Langerhans-cell ; Langerhans Cells ; Pediatrics ; Recurrence ; Simplexvirus ; Skin ; Skin Diseases ; Staining And Labeling ; Vacuoles