A Gnogenic myeloid metaplasia may best be defined as a disorder involving hematopoiesis outside the usual marrow sites, most frequently accompanied by fibrosis of the marrow. This condition represents a distinct clinical-hematologic-roentgenologic entity, with characteristic features. The literature dealing with this disease is voluminous and confused. References are made to primary and secondary forms and some investigators have even considered it to be a variant of leukemia, including it among the “myeloproliferative disorders.” Synonyms include “pseudoleukemia with splenic-cachexia,” “osteosclerosis with myelofibrosis,” “splenic pseudoleukemia,” “aleukemic myelosis,” “myeloproliferative syndrome,” “myeloid metaplasia,” “panmyelosis,” “megakaryocytic myelosis,” etc. The term agnogenic myeloid metaplasia is becoming increasingly acceptable. It is not within the purview of this presentation to review and evaluate the entire literature. Some of the classic articles which may best be read in the original ar...