Disseminated histiocytosis with undetermined Langerhans' cells simulating an acute non lymphoid leukemia

The authors report on a case of disseminated Langerhans' cell histiocytosis with a clinical presentation and a bone marrow simulating, at onset, an acute leukemia non lymphoid. A hepatic needle biopsy performed for the progressive enlargement of the liver oriented the diagnosis towards a Langerhans' cell histiocytosis. The morphological, immunohistochemical and ultrastructural study of these cells showed them to be undetermined, i.e. Langerhans' cell precursors.