[Splenic extramedullary hematopoiesis in myelofibrosis. Pathogenetic considerations apropos of a personally studied case].

A case of myelofibrosis developing in a peripheral leukaemia-type situation after splenectomy is presented. An examination of the hypotheses on the pathogenesis of myeloid metaplasia during myelofibrosis lead to the proposition that it may be caused by the "seeding" of medullary precursors in the spleen.