García-Rodríguez, EstherBernabeu-Wittel, JoséCalderón-López, GemmaPavón-Delgado, Antonio2023-01-252023-01-252016-04-01http://hdl.handle.net/10668/9996Langerhans cell histiocytosis is a systemic disease associated with the proliferation of this type of cells in tissues. Its prevalence is estimated at 1-9/100 000. Bone is the most frequently affected organ, followed by the skin, lymph nodes, haematopoietic system, pituitary gland, lungs and liver. In the majority of cases, onset occurs during childhood, with peak between one and three years of age, and poor prognosis before two years of age. The haematological forms (pancytopenia) are usually aggressive in infants. We report a case of Langerhans cell histiocytosis with neonatal onset and complex diagnosis: maintained and significant leukocytosis was the predominant data for the first two months of life, so some type of leukemia was considered. However, the most common blood disorder in Langerhans cell histiocytosis is pancytopenia rather than leukocytosis, so that the diagnosis was delayed.esImmunohistochemistryLangerhans cell histiocytosisLeukocytosisNewbornAge of OnsetHistiocytosis, Langerhans-CellHumansInfant, Newbornresearch article27079402open access10.5546/aap.2016.e1041668-3501https://doi.org/10.5546/aap.2016.e104