|Classification and external resources|
Myelophthisic anemia (or myelophthisis) is a severe kind of anemia found in some people with diseases that affect the bone marrow. Myelophthisis refers to the displacement of hemopoietic bone-marrow tissue  either by fibrosis, tumors or granulomas.
Myelophthisis can occur in the setting of chronic myeloproliferative disease (e.g. myelofibrosis), leukemia, lymphoma, and metastatic carcinoma or myeloma. It is common in people who have chronic idiopathic myelofibrosis. It has been linked to small-cell lung cancer, breast cancer or prostate cancer that metastasizes to the bone marrow.
The first test for diagnosis myelophthisis involves looking at a small sample of blood under a microscope. Myelophthisis is suggested by the presence of red blood cells that contain nuclei or are teardrop-shaped (dacryocytes), or immature granulocyte precursor cells which indicates leukoerythroblastosis is occurring because the displaced hematopoietic cells begin to undergo extramedullary hematopoiesis. These immature granulocytes are seen in peripheral blood smears. Diagnosis is confirmed when a bone marrow biopsy demonstrates significant replacement of the normal bone marrow compartment by fibrosis, malignancy or other infiltrative process. The presence of immature blood cell precursors helps distinguish another cause of pancytopenia, aplastic anemia, from myelophthisic anemia because in aplastic anemia the hematopoietic cells are damaged and immature blood cells are not seen in the peripheral blood.
The most common cause is replacement of bone marrow by metastatic cancer (tramedullary hematopoiesis tends to be modest. Other causes include myeloproliferative disorders (especially late-stage or spent polycythemia vera), granulomatous diseases, and (lipid) storage diseases. Myelofibrosis can occur in all of these. Factors that may contribute to decreased RBC production include a decreased amount of functioning hematopoietic tissue, disordered metabolism related to the underlying disorder, and, in some cases, erythrophagocytosis. Extramedullary hematopoiesis or disruption of the marrow sinusoids causes release of immature cells. Abnormally shaped RBCs often result in increased RBC destruction.
- American Society of hematology self-assessment program, second edition, 2005, page 82.
- "Myelophthisic Anemia: Anemias Caused by Deficient Erythropoiesis: Merck Manual Professional". Retrieved 2008-03-08.
- Makoni SN, Laber DA (May 2004). "Clinical spectrum of myelophthisis in cancer patients". Am. J. Hematol. 76 (1): 92–3. doi:10.1002/ajh.20046. PMID 15114608.