[Pulmonary histiocytosis X. Report of a case and review of the literature].

Histiocytosis X or Langerhans cell histiocytosis is an infrequent disease, which consists on proliferation of Langerhans cells. The etiology is unknown. Diagnosis is reached by electron microscope study of the biopsy, in which the Birbeck intracytoplasmatic granules of the Langerhans cells are found and/or by immunohistochemistry procedures able to detect S-100 antigen and CD1 cells. Diagnosis can also be reached with a bronchoalveolar lavage in which CD1 cells will appear in a score higher than 5%. We present the case of a 16 year-old girl that first appeared with a pulmonary lesion with a honey comb X-ray pattern and unsyntomatic mandibular bone affectation. Diagnosis was reached by biopsy study using S-100 antigen detection procedures. We consider this case an important one due to the infrequency of this particular disease.