Langerhans' cell histiocytosis pathobiology and pathogenesis.

Abstract

ANGERHANS L CELL histiocytosis (LCH) is one of several syndromes in which histiocytes play a principal role in pathogenesis outside of the context of inflammation and metabolic storage diseases. The leukemias and “lymphomas” that feature histiocytes (Table 1) are generally regarded as being malignant neoplastic histiocytosis syndromes but others, including LCH, are more difficult to classify (Table 2). Among these, LCH is the most significant in terms of prevalence, morbidity and mortality. The pace of research dealing with histiocytes that is revalent to an insight into LCH is frenzied and has resulted in a jungle of literature on the subject. Before addressing the pathobiology and pathogenesis of LCH, an attempt will be made to provide an infrastructure based on information about histiocytes; their ontogeny, markers and nosology, the phenomenon of activation of the cellular immune system, and metamorphosis of histiocytes.