• A chronic myeloproliferative neoplasm characterized by bone marrow fibrosis, proliferation of atypical megakaryocytes and granulocytes in the bone marrow, anemia, splenomegaly, and extramedullary hematopoiesis. (WHO, 2001)
  NCI
  U.S. National Cancer Institute, 2021
• A de novo myeloproliferation arising from an abnormal stem cell. It is characterized by the replacement of bone marrow by fibrous tissue, a process that is mediated by CYTOKINES arising from the abnormal clone.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• (agnogenic myeloid metaplasia) A progressive, chronic disease in which the bone marrow is replaced by fibrous tissue and blood is made in organs such as the liver and the spleen, instead of in the bone marrow. This disease is marked by an enlarged spleen and progressive anemia.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• Primary myelofibrosis (PMF) is a chronic myeloproliferative neoplasm characterized by bone marrow fibrosis, splenomegaly, and anemia with nucleated and teardrop-shaped red blood cells. Diagnosis requires bone marrow examination and exclusion of other conditions that can cause myelofibrosis (secondary myelofibrosis). Treatment is often...
  Merck Manuals
  Merck & Co., Inc., 2025
• Primary myelofibrosis is a clonal disorder arising from the neoplastic transformation of early hematopoietic stem cells. Older terms for this disorder include agnogenic myeloid metaplasia with myelofibrosis and chronic idiopathic myelofibrosis.
  Medscape
  WebMD, 2025
• Primary myelofibrosis is a condition characterized by the buildup of scar tissue (fibrosis) in the spongy tissue tissue inside the bone (bone marrow), the tissue that contains the stem cells that will produce blood cells. Because of the fibrosis, the bone marrow is unable to make enough normal blood cells. In myelofibrosis, the bone...
  NIH Genetic and Rare Diseases
  National Center for Advancing Translational Sciences