Idiopathic myelofibrosis (Agnogenic myeloid metaplasia) in a marmoset (Callithrix jacchus): Hematologic and histopathologic changes

Idiopathic myelofibrosis (IMF), or agnogenic myeloid metaplasia, was diagnosed in a sexually mature male marmoset (Callithrix jacchus) based on the results of hematology and histopathology evaluation of the bone marrow. The hematologic changes included pancytopenia, leukoerythroblastosis, anisocytosis, poikilocytosis, and giant platelets. Histopathologic evaluation of the bone marrow showed marked widespread fibrosis replacing hematopoietic cells and the presence of atypical megakaryocytes. In addition, slight multifocal osteolysis with an increase in serum alkaline phosphatase activity was observed. We believe this is the first report of IMF in a nonhuman primate species.