單純紅血球再生不良

Buzzwords → Dx

Diagnostic Criteria

• Severe anemia (Hb often <8) with retic count <1 % or <10 ×10⁹/L.
• Marrow biopsy: <0.5 % erythroblasts; normal granulopoiesis + megakaryopoiesis.
• Cause-specific tests:
  • Parvovirus B19 PCR (most sensitive)
  • CT chest for thymoma
  • PB flow + TCR clonality for T-LGL
  • Drug review
  • Anti-EPO antibodies if EPO-treated

Workup

• CBC + smear + retic count (classic isolated red cell suppression).
• Bone marrow aspirate + biopsy (look for giant proerythroblasts of parvovirus).
• Parvovirus B19 PCR (more sensitive than serology in immunocompromised).
• CT chest for thymoma.
• PB flow cytometry + TCR γ/β clonality for T-LGL.
• Anti-EPO antibodies if recombinant EPO history.
• Drug review (MMF, phenytoin, azathioprine, isoniazid).
• HIV, hepatitis serologies.
• ABO compatibility check in post-HCT patients.
• Pregnancy test in females.

Treatment Algorithm

flowchart TD
  A[Confirmed PRCA] --> B[Identify cause]
  B --> C{Cause}
  C -- parvovirus B19 --> D[IVIG 0.4 g/kg × 5 d<br>or 1-2 g/kg over 1-2 d<br>repeat if relapse]
  C -- thymoma --> E[Thymectomy<br>± immunosuppression]
  C -- T-LGL leukemia --> F[Cyclosporine, MTX, or cyclophosphamide<br>persistent — JAK inhibitors]
  C -- drug-induced --> G[Discontinue offending agent]
  C -- anti-EPO antibodies --> H[Discontinue EPO<br>immunosuppression<br>switch to alternative]
  C -- post-HCT (ABO major mismatch) --> I[Time + donor RBC transfusion<br>rituximab if persistent]
  C -- DBA congenital --> J[Steroids first-line<br>chronic transfusions + chelation<br>HCT for steroid refractory]
  C -- idiopathic / autoimmune --> K[Prednisone ± cyclosporine<br>rituximab if refractory]
  D --> L[Supportive RBC transfusion]
  E --> L
  F --> L
  K --> L

Pearls / Pitfalls

• Parvovirus B19 + SCD or hereditary spherocytosis = aplastic crisis (transient PRCA, 2–4 wk). Treat with IVIG + supportive transfusion.
• Parvovirus PCR is more sensitive than serology in immunocompromised hosts — they may not mount IgG/IgM.
• Thymoma + PRCA = always order CT chest in new PRCA. Thymectomy can resolve PRCA.
• T-LGL leukemia + PRCA: chronic LGL > 0.5 ×10⁹/L, CD3+ CD8+ CD57+ TCR clonal — treat with low-dose immunosuppression (CsA, MTX, cyclophosphamide).
• Anti-EPO antibodies are rare with current ESA formulations (older EPO formulations were more immunogenic) — present as resistant anemia despite EPO.
• DBA (Diamond-Blackfan) in infancy: steroid-responsive (~80 %); chronic transfusion + chelation; HCT for steroid-refractory. Increased AML / MDS / solid tumor risk.
• Post-HCT PRCA with ABO major mismatch: persistent host iso-agglutinins destroy donor RBC precursors; treat with time, rituximab if persistent, donor lymphocyte infusion.
• Pregnancy-associated PRCA typically resolves postpartum.
• Drug-induced is reversible after withdrawal — usually weeks to months.

Cross-references

• AA — broader marrow failure
• SCD — parvovirus aplastic crisis
• HS — parvovirus aplastic crisis
• T-LGL leukemia

相關題目

• Q-120 — HS — parvovirus B19 aplastic crisis
• Q-139 — PRCA — thymoma association
• Q-140 — PRCA — parvovirus B19 in immunocompromised
• Q-141 — PRCA — T-LGL leukemia association

Sources