Pure red cell aplasia is a rare bone marrow failure syndrome characterized by normocytic normochromic anemia, severe reticulocytopenia (<10 × 10⁹/L), and marked reduction or absence of erythroid precursors (<5%) on bone marrow examination, with preserved granulopoiesis and megakaryopoiesis. [1-2] The estimated annual incidence is approximately 1.06 per million. [2] Approximately 50% of cases are idiopathic; the remainder are secondary to lymphoproliferative disorders, infections, autoimmune diseases, thymoma, drugs, or solid tumors. [1][3]
1. History
- Onset and duration of fatigue, dyspnea on exertion, exercise intolerance, pallor
- Gradual vs. acute onset (gradual onset is typical; acute suggests parvovirus B19 aplastic crisis in patients with underlying hemolytic anemias) [4]
- Transfusion history and frequency — many patients present profoundly anemic (mean Hb ~6.6 g/dL at diagnosis) [2]
- Prior or concurrent autoimmune conditions (SLE, rheumatoid arthritis, myasthenia gravis, Graves' disease) [2][4]
- History of thymoma or anterior mediastinal mass [2]
- Medication exposure: erythropoiesis-stimulating agents (ESAs), phenytoin, valproate, carbamazepine, azathioprine, isoniazid, chloramphenicol, sulfonamides, procainamide, immune checkpoint inhibitors [4-6]
- Recent viral illness (parvovirus B19, EBV, hepatitis, HIV, COVID-19) [4]
- History of hematopoietic stem cell transplant with ABO mismatch [7-8]
- Immunosuppression status (HIV, organ transplant, chemotherapy)
- Pregnancy (rare association)
2. Alarm Features
- Hemoglobin <7 g/dL with symptomatic anemia (chest pain, syncope, high-output heart failure) — many patients present with Hb in the 4–7 g/dL range [2]
- Rapidly progressive anemia unresponsive to ESAs in CKD patients (suspect anti-EPO antibody-mediated PRCA) [9-10]
- Concurrent cytopenias (neutropenia, thrombocytopenia) — suggests aplastic anemia, MDS, or LGL leukemia rather than isolated PRCA [6]
- New anterior mediastinal mass on imaging (thymoma) [2]
- Signs of underlying malignancy (lymphadenopathy, splenomegaly, B symptoms)
- Features of Good syndrome: thymoma + hypogammaglobulinemia + recurrent infections [2]
- Hemodynamic instability from severe anemia
3. Medications
Drug-induced PRCA (offending agents to identify and discontinue):
- Erythropoiesis-stimulating agents (epoetin alfa, darbepoetin, CERA) — anti-EPO antibody-mediated PRCA, particularly with subcutaneous administration. The FDA label for epoetin alfa warns that PRCA should be suspected when response to ESA is lost, and the drug must be permanently discontinued [9-12]
- Antiepileptics: phenytoin, valproate, carbamazepine [4]
- Immunosuppressants: azathioprine [4]
- Antibiotics: chloramphenicol, sulfonamides, isoniazid [4]
- Antiarrhythmics: procainamide [4]
- Immune checkpoint inhibitors [6]
Treatment medications
- Cyclosporine A (CsA) ± corticosteroids — first-line; overall response rate ~70–76% [3][13]
- Corticosteroids — initial response rate ~67–77%, but frequent relapse on taper [2][14]
- Cyclophosphamide — second-line, lower response than CsA [3]
- IVIG — specifically effective for parvovirus B19-associated PRCA and hypogammaglobulinemia-associated cases [3]
- Salvage agents: alemtuzumab (especially for LGL leukemia-associated), rituximab, ATG, bortezomib, sirolimus, daratumumab (post-HSCT setting) [2-3][7]
- Roxadustat (HIF-PHI) — emerging evidence for anti-EPO antibody-mediated PRCA in CKD patients [15-16]
Contraindicated: Do not re-expose to any ESA product if anti-EPO antibody-mediated PRCA is confirmed [10]
4. Diet
- No specific dietary triggers or restrictions for PRCA itself
- Iron overload from chronic transfusions is a major concern — iron chelation therapy may be needed; avoid unnecessary iron supplementation [8][17]
- Adequate folate and B12 intake to support erythropoiesis once treatment response begins
- Immunosuppressed patients should follow food safety precautions (avoid raw/undercooked foods)
5. Review of Systems
- Constitutional: fatigue, weakness, exercise intolerance, dizziness, weight loss
- Cardiovascular: dyspnea on exertion, palpitations, chest pain (high-output state)
- Neurologic: headache, difficulty concentrating, syncope
- Musculoskeletal: myasthenia symptoms (ptosis, diplopia, dysphagia) — thymoma association [2]
- Infectious: recurrent infections (Good syndrome, immunosuppression) [2]
- Rheumatologic: joint pain, rash, photosensitivity (SLE association) [17]
- Hematologic: easy bruising, bleeding (if concurrent cytopenias)
- GI: abdominal pain, hepatosplenomegaly (lymphoproliferative disorders)
6. Collateral History and Family History
- Family history of congenital anemias or Diamond-Blackfan anemia (congenital PRCA — presents in infancy with physical anomalies in ~50%) [4][18]
- Family history of autoimmune diseases (SLE, thyroid disease)
- History of blood product transfusions and reactions
- Social history: occupational exposures to toxins, travel history (parvovirus exposure)
- In pediatric patients: distinguish from transient erythroblastopenia of childhood (TEC), which is self-resolving [4]
7. Risk Factors
- Lymphoproliferative disorders: CLL, LGL leukemia (most common hematologic association) [1][14]
- Thymoma: found in ~10–22% of PRCA patients; conversely, 2–5% of thymoma patients develop PRCA [2][18]
- Autoimmune diseases: SLE, rheumatoid arthritis, myasthenia gravis [1][17]
- Infections: parvovirus B19 (especially in immunocompromised), HIV, EBV, hepatitis, COVID-19 [4]
- Drug exposure: ESAs (especially subcutaneous epoetin alfa), antiepileptics, azathioprine [4][9]
- ABO-incompatible allogeneic HSCT: incidence 10–30% [7-8]
- Immune checkpoint inhibitor therapy [6]
- Clonal hematopoiesis: STAT3 mutations, DNMT3A, TET2 mutations detected in ~62% of patients [19-20]
- HLA associations: HLA-B46:01 and HLA-DRB109:01 associated with anti-EPO PRCA (particularly in Asian populations) [21]
8. Differential Diagnosis
- Aplastic anemia — pancytopenia with hypocellular marrow (all lineages affected, unlike PRCA) [6][22]
- Myelodysplastic syndrome (MDS) — may present with PRCA morphology; 5q deletion syndrome is a specific overlap [1][4]
- Iron deficiency anemia — microcytic, low ferritin, responds to iron
- B12/folate deficiency — megaloblastic anemia with macrocytosis
- Anemia of chronic disease/inflammation — typically mild-moderate, elevated ferritin
- Hemolytic anemias — elevated reticulocyte count (opposite of PRCA), elevated LDH, low haptoglobin
- Renal anemia — low EPO levels, responds to ESAs (unless anti-EPO PRCA)
- Transient erythroblastopenia of childhood (TEC) — self-resolving, age >1 year, normal eADA [4]
- Diamond-Blackfan anemia — congenital, presents in infancy, elevated eADA, macrocytic [4]
- Large granular lymphocyte (LGL) leukemia — may present as PRCA; check flow cytometry and TCR rearrangement [3][14]
9. Past Medical History
- Prior episodes of unexplained anemia or transfusion dependence
- Known thymoma or prior thymectomy [2][23]
- Autoimmune conditions (SLE, RA, myasthenia gravis, thyroid disease) [2]
- Lymphoproliferative disorders (CLL, lymphoma, LGL leukemia) [1]
- CKD and ESA use history [9]
- Prior HSCT with ABO mismatch [7]
- Solid organ transplant and immunosuppressive regimen [24]
- History of parvovirus B19 infection
- Malignancy and treatment history (checkpoint inhibitors, chemotherapy) [6]
10. Physical Exam
- Vital signs: tachycardia, hypotension (if severely anemic), tachypnea
- General: pallor (conjunctival, palmar, nail beds), fatigue
- HEENT: conjunctival pallor, scleral icterus (absent in PRCA — no hemolysis)
- Cardiovascular: flow murmur, S3 gallop (high-output failure in severe anemia)
- Chest: anterior mediastinal mass (thymoma — may not be palpable)
- Abdomen: hepatosplenomegaly (lymphoproliferative disorders), no splenomegaly expected in isolated idiopathic PRCA
- Lymph nodes: lymphadenopathy (CLL, lymphoma)
- Neurologic: ptosis, fatigable weakness (myasthenia gravis with thymoma) [2]
- Skin: petechiae/purpura (if concurrent thrombocytopenia — suggests broader marrow failure), malar rash (SLE)
- Notably absent: jaundice and splenomegaly (which would suggest hemolysis rather than PRCA)
11. Lab Studies
Diagnostic labs
- CBC with differential: normocytic normochromic anemia, WBC and platelets typically normal [1][22]
- Reticulocyte count: severely depressed, typically <10 × 10⁹/L (often <1%) — this is the hallmark finding [2][22]
- Peripheral blood smear: normocytic normochromic RBCs, no schistocytes, no spherocytes
Etiologic workup
- Parvovirus B19: IgM/IgG serology AND PCR (serology may be negative in immunocompromised) [2][4]
- HIV testing [4]
- Hepatitis B and C serologies [4]
- ANA, anti-dsDNA (SLE screen) — ANA positive in ~56% of thymoma-associated PRCA [2]
- Direct antiglobulin test (DAT) [2][6]
- Serum immunoglobulins (hypogammaglobulinemia → Good syndrome) [2]
- LDH, haptoglobin, indirect bilirubin — to exclude hemolysis (should be normal/near-normal in PRCA) [2]
- Serum EPO level — typically elevated (unless anti-EPO antibody-mediated) [25]
- Anti-EPO antibodies — if CKD patient on ESAs with loss of response [9-10]
- Flow cytometry (peripheral blood): T-cell and NK-cell subsets, CD3+CD8+CD57+ expansion (LGL leukemia) [3][20]
- TCR gene rearrangement [20]
- SPEP/UPEP with immunofixation (B-cell dyscrasia screen) [3]
- Iron studies, ferritin (iron overload from transfusions) [8]
Monitoring parameters on treatment
- CBC with reticulocyte count (response marker)
- Cyclosporine trough levels (target 150–250 ng/mL)
- Renal function, blood pressure, magnesium (cyclosporine toxicity)
- Ferritin (transfusional iron overload)
12. Imaging
- CT chest with contrast: first-line to evaluate for thymoma/anterior mediastinal mass — found in 10–22% of PRCA patients. Should be obtained in all new PRCA diagnoses [2][18]
- CT abdomen/pelvis: evaluate for lymphadenopathy, hepatosplenomegaly (lymphoproliferative disorders)
- PET-CT: if malignancy suspected [2]
- Imaging is unnecessary for monitoring PRCA response (follow labs instead)
13. Special Tests
- Bone marrow aspirate and biopsy: essential for diagnosis — shows normocellular or hypocellular marrow with selective absence or marked reduction of erythroid precursors (<5%), normal granulopoiesis and megakaryopoiesis, often increased iron stores [2][18]
- Giant proerythroblasts with intranuclear inclusions suggest parvovirus B19 [18]
- Increased hematogones may mimic ALL [18]
- Flow cytometry on marrow for LGL leukemia
- Cytogenetics (5q deletion → MDS overlap) [4]
- STAT3 mutation testing: recurrently mutated in T-cell-mediated PRCA subtypes; STAT3-mutated cases may have higher IST response rates [13][20]
- Next-generation sequencing for clonal hematopoiesis genes (DNMT3A, TET2, TP53) — TP53 and DNMT3A mutations associated with worse OS [19]
- Erythrocyte adenosine deaminase (eADA): elevated in Diamond-Blackfan anemia, normal in TEC and acquired PRCA [4]
14. ECG
- ECG indicated in patients with severe anemia (Hb <7 g/dL) to evaluate for:
- Sinus tachycardia
- ST-segment changes or T-wave inversions (demand ischemia)
- Signs of right heart strain (chronic anemia with high-output state)
- No PRCA-specific ECG findings
- Continuous monitoring if hemodynamically unstable
15. Assessment
PRCA is a rare but serious cause of isolated, severe normocytic anemia with a reticulocyte count that is inappropriately low. The clinical presentation is typically insidious with progressive fatigue and pallor, though patients may present acutely with symptomatic severe anemia (mean Hb ~6.6 g/dL at diagnosis). [2]
Classification
- Congenital: Diamond-Blackfan anemia [1]
- Acquired primary (idiopathic): ~50% of cases; autoimmune, frequently antibody- or T-cell-mediated [1][3]
- Acquired secondary: lymphoproliferative disorders (LGL leukemia most common), thymoma, autoimmune diseases, infections (parvovirus B19), drugs, post-HSCT [1][14]
The pathogenesis is predominantly T-cell-mediated (autoreactive cytotoxic T cells targeting erythroid precursors), with a continuum from polyclonal to monoclonal T-cell expansion. [3][20] Antibody-mediated mechanisms also occur (anti-EPO antibodies, anti-erythroblast antibodies). [1][9]
Complications: transfusion dependence, transfusional iron overload, infectious complications from immunosuppressive therapy (major cause of morbidity/mortality), and relapse (54% of thymoma-associated cases experience multiple relapses). [2][17][26]
16. Treatment Plan
Initial stabilization
- RBC transfusion for symptomatic severe anemia — most patients require transfusion support at diagnosis [2]
- Identify and treat underlying cause (discontinue offending drug, treat parvovirus B19, address thymoma)
Etiology-specific treatment
- Parvovirus B19-associated: IVIG (0.4 g/kg/day × 5 days) — highly effective [3]
- Drug-induced: discontinue offending agent; may resolve spontaneously [4][10]
- Anti-EPO antibody-mediated: permanently discontinue all ESAs + immunosuppression (CsA or corticosteroids); roxadustat (HIF-PHI) is an emerging alternative for anemia management [10][15-16]
- Thymoma-associated: thymectomy alone rarely curative for PRCA; immunosuppressive therapy is typically required [2][23]
First-line immunosuppressive therapy (idiopathic/immune-mediated):
- Cyclosporine A (3–5 mg/kg/day, target trough 150–250 ng/mL) ± corticosteroid taper — first-line ORR ~70–76%. CsA + corticosteroids combined yields the highest efficacy (ORR ~76%) [3][13]
- Response assessment at 2–3 months; median of 2 different therapies needed to achieve remission [3]
Salvage/refractory options
- Oral cyclophosphamide [3]
- Alemtuzumab (particularly effective in LGL leukemia-associated PRCA) [3]
- Rituximab, ATG, bortezomib [3]
- Sirolimus (50% response in refractory thymoma-associated cases) [2]
- Daratumumab (promising in post-HSCT PRCA) [7-8]
- Allogeneic HSCT — potentially curative for refractory cases, but carries significant early transplant-related mortality (4/8 patients died within 3 months in one series) [27]
Iron chelation: for patients with transfusional iron overload (ferritin >1000 ng/mL)
The following swimmer plot from a French nationwide study illustrates the heterogeneous treatment courses and frequent relapses in thymoma-associated PRCA:
17. Disposition
Admission criteria
- Symptomatic severe anemia (Hb <7 g/dL, hemodynamic instability, angina, heart failure)
- Need for urgent transfusion
- New diagnosis requiring bone marrow biopsy and expedited workup
- Severe infection in immunosuppressed patient
Observation/outpatient management
- Stable patients with moderate anemia and established diagnosis can be managed outpatient with close hematology follow-up
- Initiation of immunosuppressive therapy can often be done outpatient
Specialist consultation triggers
- Hematology: all cases — PRCA requires specialist-directed workup and treatment [3][28]
- Oncology/thoracic surgery: if thymoma identified [2]
- Rheumatology: if SLE or other autoimmune disease suspected [17]
- Nephrology: if CKD-related anti-EPO antibody PRCA [9]
- Infectious disease: parvovirus B19 in immunocompromised, HIV
18. Follow Up / Return Precautions
Follow-up timing
- CBC with reticulocyte count every 1–2 weeks during initial treatment until response
- Response assessment at 2–3 months after initiating immunosuppressive therapy [3]
- Cyclosporine trough levels, renal function, and blood pressure monitoring every 2–4 weeks
- Ferritin monitoring every 1–3 months in transfusion-dependent patients
- Long-term follow-up is essential — relapse is common (56% of responders relapse in some series) [2][29]
Prognosis
- Median overall survival for primary PRCA is >10 years; for secondary PRCA, ~4 years (older data). Japanese nationwide data showed median OS not yet reached for idiopathic PRCA; ~142 months for thymoma-associated and ~148 months for LGL-associated PRCA [26][29]
- Infection is the major cause of morbidity and mortality from immunosuppressive therapy [17][26]
- Higher somatic mutation burden (TP53, DNMT3A) is associated with worse long-term outcomes [19]
Return precautions (patient counseling)
- Return immediately for worsening fatigue, dizziness, syncope, chest pain, shortness of breath, or fever
- Signs of infection (fever, chills, cough) while on immunosuppression require urgent evaluation
- Symptoms of cyclosporine toxicity: tremor, gingival hyperplasia, elevated blood pressure, decreased urine output
- Expected recovery: reticulocyte count typically rises within 2–4 weeks of effective therapy; hemoglobin normalization may take 2–3 months
- Emphasize medication adherence — premature discontinuation of CsA leads to high relapse rates [2][30]
References
1. Pure Red Cell Aplasia. — Means RT. Blood. 2016.
2. Pure Red Cell Aplasia Associated With Thymic Tumors, a Nationwide Retrospective Study. — Hemmer M, Moinard S, Lambotte O, et al. American Journal of Hematology. 2025.
3. Rational Management Approach to Pure Red Cell Aplasia. — Balasubramanian SK, Sadaps M, Thota S, et al. Haematologica. 2018.
4. DBA Syndrome. — Sieff C GeneReviews® [Internet]. 2025.
5. Hematopoietic Growth Factors. — Updated 2025-12-05. National Comprehensive Cancer Network.
6. Management of Immune Checkpoint Inhibitor-Related Toxicities. — Updated 2025-10-23. National Comprehensive Cancer Network.
7. Daratumumab in the Management of Red Cell Aplasia Following Allogeneic Hematopoietic Stem Cell Transplantation. — Desai N, Viswabandya A, Kim DDH, et al. European Journal of Haematology. 2025.
8. Pure Red Cell Aplasia Among ABO Mismatched Hematopoietic Stem Cell Transplant Recipients: A 13-Years Retrospective Study and Literature Review. — Metafuni E, Busnego Barreto MT, Valentini CG, et al. Frontiers in Oncology. 2024.
9. Pure Red-Cell Aplasia and Antierythropoietin Antibodies in Patients Treated with Recombinant Erythropoietin. — Casadevall N, Nataf J, Viron B, et al. The New England Journal of Medicine. 2002.
10. FDA Drug Label. — Updated date: 2025-06-22. Food and Drug Administration.
11. Anti-Erythropoietin Antibody-Mediated Pure Red Cell Aplasia After Treatment With Recombinant Erythropoietin Products: Recommendations for Minimization of Risk. — Cournoyer D, Toffelmire EB, Wells GA, et al. Journal of the American Society of Nephrology : JASN. 2004.
12. Pure Red-Cell Aplasia and Epoetin Therapy. — Bennett CL, Luminari S, Nissenson AR, et al. The New England Journal of Medicine. 2004.
13. Efficacy and Influencing Factors of Immunosuppressive Therapy for Pure Red Cell Aplasia: Meta-Analysis and Systematic Review. — Yusup M, He G, Qin Y, Tuerxun N, Hao J. Annals of Hematology. 2025.
14. Clinical Characteristics and Outcomes of 100 Adult Patients With Pure Red Cell Aplasia. — Wu X, Cheng L, Liu X, et al. Annals of Hematology. 2022.
15. A Rising Cluster of Erythropoietin-Associated Pure Red Cell Aplasia and Subsequent Response to Roxadustat: A Case Series. — Devathasan J, Goh TL, Lin DC, et al. Nephrology. 2026.
16. Roxadustat on anti‐erythropoietin antibody‐related pure red cell aplasia in the patient with end‐stage renal disease. — Wu R, Peng Y. Seminars in Dialysis. 2021.
17. Pure Red Cell Aplasia in Systemic Lupus Erythematosus, a Nationwide Retrospective Cohort and Review of the Literature. — Lobbes H, Mahévas M, Alviset S, et al. Rheumatology. 2021.
18. The pathology of bone marrow failure. — Leguit RJ, van den Tweel JG. Histopathology. 2010.
19. Somatic Mutations and Mutation Burden Predict Treatment Response and Survival in Adult Acquired Pure Red Cell Aplasia. — Yang L, Zhang H, Wei Y, et al. American Journal of Hematology. 2026.
20. T Cell Clonal Expansion and STAT3 Mutations: A Characteristic Feature of Acquired Chronic T Cell-Mediated Pure Red Cell Aplasia. — Kawakami F, Kawakami T, Yamane T, et al. International Journal of Hematology. 2022.
21. HLA-B*46:01:01:01 and HLA-DRB1*09:01:02:01 Are Associated With Anti-rHuEPO-Induced Pure Red Cell Aplasia. — Suttichet TB, Chamnanphon M, Pongpanich M, et al. Scientific Reports. 2023.
22. Recommendations on haematological criteria for the diagnosis of epoetin‐induced pure red cell aplasia. — Casadevall N, Cournoyer D, Marsh J, et al. European Journal of Haematology. 2004.
23. Thymoma and pure red cell aplasia: A single institution experience. — Tara Seibert , Patrick J. Loehrer Sr. and Andrew O'Brien Journal of Clinical Oncology. 2022.
24. Case Report: Dynamic Antibody Monitoring in a Case of Anti-Recombinant Human Erythropoietin-Mediated Pure Red Cell Aplasia With Prolonged Course After Kidney Transplantation. — Chen XM, Li H, Wu Y, et al. Frontiers in Immunology. 2022.
25. Successful Treatment of Antibody-Mediated Pure Red Cell Aplasia Induced by Continuous Erythropoietin Receptor Activator With Prednisolone. — Okahashi N, Kubo M, Hoshino E, et al. Internal Medicine. 2022.
26. Long-Term Outcome of Patients With Acquired Chronic Pure Red Cell Aplasia (PRCA) Following Immunosuppressive Therapy: A Final Report of the Nationwide Cohort Study in 2004/2006 by the Japan PRCA Collaborative Study Group. — Hirokawa M, Sawada K, Fujishima N, et al. British Journal of Haematology. 2015.
27. Outcomes of Allogeneic Hematopoietic Stem Cell Transplantation for Acquired Pure Red Cell Aplasia. — Noguchi Y, Mori T, Onishi Y, et al. International Journal of Hematology. 2026.
28. How I Manage Acquired Pure Red Cell Aplasia in Adults. — Gurnari C, Maciejewski JP. Blood. 2021.
29. Studies on Pure Red Cell Aplasia. XI. Results of Immunosuppressive Treatment of 37 Patients. — Clark DA, Dessypris EN, Krantz SB. Blood. 1984.
30. Acquired Pure Red Cell Aplasia: Updated Review of Treatment. — Sawada K, Fujishima N, Hirokawa M. British Journal of Haematology. 2008.