agnogenic myeloid metaplasia

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Related to agnogenic myeloid metaplasia: polycythemia vera


the change in the type of adult cells in a tissue to a form abnormal for that tissue. adj., adj metaplas´tic.
agnogenic myeloid metaplasia the primary or idiopathic form of myeloid metaplasia, which is often accompanied by myelofibrosis; it is considered one of the myeloproliferative disorders. Called also aleukemic or nonleukemic myelosis.
myeloid metaplasia the occurrence of myeloid tissue in extramedullary sites; specifically, a syndrome characterized by splenomegaly, anemia, nucleated erythrocytes and immature granulocytes in the circulating blood, and extramedullary hematopoiesis in the liver and spleen. The primary form is called agnogenic myeloid metaplasia. The secondary or symptomatic form may be associated with various diseases, including carcinomatosis, tuberculosis, leukemia, and polycythemia vera.

pri·mar·y my·e·loid met·a·pla·si·a

myeloid metaplasia occurring as the primary condition, often in association with myelofibrosis.

agnogenic myeloid metaplasia

chronic idiopathic myelofibrosis

A chronic progressive condition characterised by panmyelosis and variable marrow fibrosis, massive splenomegaly secondary to extramedullary haematopoiesis, and leukoerythroblastic anaemia with dysmorphic red blood cells, circulating normoblasts, immature white blood cells and atypical platelets.
Clinical findings
Patients are often > age 50, suffer from insidious weight loss, anaemia, and abdominal discomfort due to splenomegaly, often with hepatomegaly; 80% have nonspecific chromosome defects.
Bone marrow biopsy.
No specific therapy; packed RBCs for anaemia; androgens may reduce transfusion requirements, but are poorly tolerated in women; recombinant erythropoietin.
Survival ± 5 years, often progresses to acute leukaemia.

No name used for this condition has proven consistently satisfactory to those who work in the field. Chronic idiopathic myelofibrosis is preferred by the World Health Organisation, while others prefer the term primary myelofibrosis. None of the terms fully take into account the functional defects—e.g., haemopoietic stem cell disturbance, extramedullary haemopoiesis and the pathological changes seen in the bone marrow (e.g., intense marrow fibrosis).

agnogenic myeloid metaplasia

Myelofibrosis with myeloid metaplasia Hematology A chronic progressive condition–panmyelosis and variable BM fibrosis, massive splenomegaly 2º to extramedullary hematopoiesis and leukoerythroblastic anemia with dysmorphic RBCs, circulating normoblasts, immature WBCs, atypical platelets Clinical Pts are often > age 50, insidious weight loss, anemia, abdominal discomfort due to splenomegaly, often with hepatomegaly; 80% have nonspecific chromosome defects Diagnosis BM Bx Management No specific therapy; packed RBCs for anemia, androgens may ↓ transfusion requirements, but are poorly tolerated in ♀; recombinant erythropoietin Prognosis Survival ± 5 yrs, often → acute leukemia. See Pseudonym syndrome.


of unknown origin.

agnogenic myeloid metaplasia
see myeloid metaplasia.