Chapter 102. Aplastic Anemia, Myelodysplasia, and Related Bone Marrow Failure Syndromes (Part 12) Pure Red Cell Aplasia: Treatment History, physical examination, and routine laboratory studies may disclose an underlying disease or a suspect drug exposure. Thymoma should be sought by radiographic procedures. Tumor excision is indicated, but anemia does not necessarily improve with surgery. The diagnosis of parvovirus infection requires detection of viral DNA sequences in the blood (IgG and IgM antibodies are commonly absent). The presence of erythroid colonies has been considered predictive of response to immunosuppressive therapy in idiopathic PRCA. Red cell aplasia is compatible with long survival with supportive care alone: a combination of erythrocyte transfusions and iron chelation. For persistent B19 parvovirus infection, almost all patients respond to intravenous immunoglobulin therapy (for example, 0.4 g/kg daily for 5 days), although relapse and retreatment may be expected, especially in patients with AIDS. The majority of patients with idiopathic PRCA respond favorably to immunosuppression. Most first receive a course of glucocorticoids. Also effective are cyclosporine, ATG, azathioprine, cyclophosphamide, and the monoclonal antibodydaclizumab, an antibody to the IL-2 receptor. PRCA developing on erythropoietin therapy should be treated with immunosuppression and withdrawal of erythropoietin. Myelodysplasia Definition The myelodysplasias (MDSs) are a heterogeneous group of hematologic disorders broadly characterized by cytopenias associated with a dysmorphic (or abnormal appearing) and usually cellular bone marrow, and by consequent ineffective blood cell production. A clinically useful nosology of these entities was first developed by the French-American-British Cooperative Group in 1983. Five entities were defined: refractory anemia (RA), refractory anemia with ringed sideroblasts (RARS), refractory anemia with excess blasts (RAEB), refractory anemia with excess blasts in transformation (RAEB-t), and chronic myelomonocytic leukemia (CMML). The World Health Organization classification (2002) recognizes that the distinction between RAEB-t and acute myeloid leukemia is arbitrary and groups them together as acute leukemia, notes that CMML behaves as a myeloproliferative disease, and separates refractory anemias with dysmorphic change restricted to erythroid lineage from those with multilineage changes (Table 102-5). Table 102- 5 World Health Organization Classification of Myelodysplastic Syndromes Disease Freque ncy Blood Findings Bone Marrow Findings Prognos is Refractory anemia (RA) 5–10% Anemia No or rare blasts Erythro id dysplasia only <5% blasts <15% ringed sideroblasts Protract ed course Leukem ic transformation in ~6% Refractory anemia with ringed sideroblasts 10–12% Anemia No blasts Erythro id dysplasia only Protract ed course Leukem (RARS) ≥15% ringed sideroblasts <5% blasts ia in ~1–2% Refractory cytopenia with multilineage dysplasia (RCMD) 24% Cytope nias (2 or 3 lineages) No or rare blasts No Auer rods <1 x 10 9 /L monocytes Dysplas ia in ≥10% of cells in ≥2 lineages <5% blasts No Auer rods <15% ringed sideroblasts Variable clinical course Leukem ia in ~11% RCMD with 15% Cytope Dysplas ringed sideroblasts (RCMD-RS) nias (2 or 3 lineages) No or rare blasts No Auer rods <1 x 10 9 /L monocytes ia in ≥10% of cells in ≥2 lineages ≥15% ringed sideroblasts <5% blasts No Auer rods Refractory anemia with excess blasts-1 (RAEB-1) 40% (RAEB- 1 +2) Cytope nias <5% blasts No Auer rods <1 x Uniline age or multilineage dysplasia 5–9% blasts No Progress ive BM failure Leukem ia in ~25% 10 9 /L monocytes Auer rods Refractory anemia with excess blasts-2 (RAEB-2) Cytope nias 5–19% blasts ±Auer rods <1 x 10 9 /L monocytes Uniline age or multilineage dysplasia 10– 19% blasts ±Auer rods Progress ive BM failure Leukem ia in ~33% Myelodyspl astic syndrome, unclassified (MDS- U) Unkno wn Cytope nias No or rare blasts No Dysplas ia in myeloid or platelet lineage <5% blasts Unknow n Auer rods No Auer rods MDS with isolated del(5q) Unkno wn Anemia <5% blasts Platelet s nl or increased Nl or increased megakaryocyt es w ith hypolobated nuclei <5% blasts No Auer rods Isolated del(5q) Long survival Note: BM, bone marrow. Source: Extracted from Jaffe ES et al (eds): Pathology and Genetics of Tumors of Haematopoietic and Lymphoid Tissues. Lyon, IARC Press, 2001. . Chapter 102. Aplastic Anemia, Myelodysplasia, and Related Bone Marrow Failure Syndromes (Part 12) Pure Red Cell Aplasia: Treatment History, physical examination, and routine. characterized by cytopenias associated with a dysmorphic (or abnormal appearing) and usually cellular bone marrow, and by consequent ineffective blood cell production. A clinically useful nosology. Isolated del(5q) Long survival Note: BM, bone marrow. Source: Extracted from Jaffe ES et al (eds): Pathology and Genetics of Tumors of Haematopoietic and Lymphoid Tissues. Lyon, IARC Press,