Чиста еритроцитарна аплазія

Pure red blood cell (RBC) aplasia is most often due to an inappropriate immune response causing suppression of erythropoiesis. Well-known causes include

• ABO-mismatched bone marrow transplant

• Autoimmune disorders/collagen vascular diseases (systemic lupus erythematosus, rheumatoid arthritis)

• Medications (eg, tranquilizers, antiseizure medications, recombinant erythropoietin, immune checkpoint inhibitors)

• HIV infection

• Lymphoproliferative diseases (chronic lymphocytic leukemia, large granular lymphocyte leukemia, chronic myeloid leukemia, Hodgkin lymphoma, non-Hodgkin lymphoma, multiple myeloma/plasma cell disorders)

• Parvovirus B19, particularly in immunocompromised patients such as those with HIV infection or chronic hemolytic anemias (the parvovirus binds to the blood group P antigen on erythroid precursors and is directly cytotoxic to the cells)

• Pregnancy

• Riboflavin deficiency

• Solid tumors

• Thymomas

• Toxins (organic phosphates)

Symptoms of pure RBC aplasia are generally mild and relate to the degree of the anemia or to the underlying disorder. The onset of pure red blood cell anemia usually is insidious, often occurring over weeks or months. Symptoms related to anemia include fatigue, lethargy, decreased exercise tolerance, and pallor.

• Complete blood count (CBC), reticulocyte count

• Bone marrow examination

• Peripheral blood smear looking for large granular lymphocytes

• Sometimes peripheral blood flow cytometry and T cell gene rearrangement testing

Pure RBC aplasia manifests with a normocytic anemia but normal white blood cell and platelet counts. Reticulocytes are decreased (absolute reticulocyte count < 10,000/microliter, reticulocyte percentage < 1%).

The bone marrow reveals normal cellularity with a maturation arrest at the proerythroblast stage. In parvovirus B19 infection, giant pronormoblasts may be present. Although not widely available, if possible, a marrow burst forming units-erythroid (BFU-E) assay should be obtained to differentiate autoimmune causes of pure red cell aplasia from primary bone marrow disorders such as myelodysplastic syndrome (1).

Chest CT is indicated to evaluate for thymoma in the absence of another identified cause.

• Immunosuppression

• Sometimes intravenous immunoglobulin (IVIG) or thymectomy

Some patients undergo spontaneous remission after an ABO-incompatible stem cell transplant, if the causative medication is stopped, or following delivery if pregnancy is the cause. 

Pure RBC aplasia has been successfully managed with immunosuppressants (eg, prednisone, cyclosporine, cyclophosphamide), especially when an autoimmune mechanism is suspected.

Pure RBC aplasia secondary to parvovirus infection is treated with intravenous immune globulin.

Thymectomy is done in patients with thymoma-associated pure RBC aplasia; most patients improve but are not always cured and require immunosuppressive agents.