急性前骨髓細胞白血病

Buzzwords → Dx

Diagnostic Criteria

• Morphology + clinical (DIC): sufficient to start ATRA empirically (board-favorite teaching point).
• Confirmation: RT-PCR or FISH for PML::RARA fusion (rapid, often <24 h). Karyotype t(15;17)(q24.1;q21.2) confirms.
• WHO 5e / ICC 2022: APL with PML::RARA is defined by the fusion alone (no blast threshold required).
• Sanz / PETHEMA risk:
  • Low risk: WBC ≤10 × 10⁹/L AND platelets >40 × 10⁹/L
  • Intermediate: WBC ≤10 AND platelets ≤40 (often grouped with low-risk in modern trials)
  • High risk: WBC >10 × 10⁹/L

Workup

• Smear + flow (CD34– / HLA-DR– / CD117+ / MPO++ in classic; microgranular looks more monocytic).
• Coagulation panel + fibrinogen + D-dimer q6h during induction (DIC monitoring).
• PML::RARA RT-PCR baseline → repeat post-induction, post-consolidation, every 3 mo × 2 yr in high-risk for MRD.
• CXR + echo before induction (DS can mimic CHF).
• No LP at diagnosis (bleeding risk); consider LP before consolidation in high-risk for CNS prophylaxis.

Treatment Algorithm

flowchart TD
  A[Suspected APL<br>faggot cells / DIC] --> B[Start ATRA NOW<br>+ aggressive blood-product support]
  B --> C{Confirmed PML::RARA?}
  C -- variant<br>PLZF::RARA / STAT5B::RARA --> D[Switch to chemo<br>ATRA/ATO ineffective]
  C -- yes --> E{Risk stratification<br>WBC threshold 10K}
  E -- low/int --> F[ATRA + ATO<br>chemo-free, induction + consolidation<br>no maintenance]
  E -- high --> G[ATRA + ATO + idarubicin<br>OR ATRA + ATO + GO<br>± CNS prophylaxis]
  F --> H[Differentiation syndrome prophylaxis<br>prednisone 0.5 mg/kg from day 1]
  G --> H
  H --> I{DS develops?}
  I -- yes --> J[Dexamethasone 10 mg BID<br>hold ATRA only if severe<br>hydroxyurea if WBC rising]
  I -- no --> K[Continue induction]
  J --> K
  K --> L[PCR for PML::RARA after consolidation<br>then q3mo × 2 yr if high-risk]

Pearls / Pitfalls

• Start ATRA on suspicion, not confirmation. Early mortality is 5.9 % in trials but >20 % in population-level data — driven by intracranial hemorrhage before treatment begins. The exam-correct answer is "start ATRA empirically".¹⁶
• Differentiation syndrome ≠ infection ≠ leukostasis. Fever + dyspnea + weight gain + effusions on ATRA → dexamethasone 10 mg BID immediately. Stopping ATRA is reserved for severe/refractory cases only. Concurrent cytotoxic chemotherapy reduces DS risk.⁵
• Variant RARA fusions are ATRA/ATO RESISTANT. t(11;17) PLZF::RARA and STAT5B::RARA do not respond — treat with conventional AML chemotherapy. PML::RARA accounts for ~95 % of APL; always confirm the fusion partner, not just "t(15;17)".⁴
• No maintenance after ATRA + ATO. That's the surprise — chemo-free regimens (APL0406, AML17) have no maintenance phase. Maintenance (ATRA ± low-dose chemo × 2 yr) only applies to ATRA + chemo regimens. Picking "give 2 yr ATRA maintenance" after ATRA+ATO is the wrong answer.⁷²
• Late CNS relapse in high-risk APL. CNS is the most common extramedullary relapse site when WBC >10. NCCN recommends LP + intrathecal prophylaxis (typically MTX + Ara-C × 5) before/during consolidation for high-risk only.¹
• Coagulopathy targets: platelets ≥30–50 K, fibrinogen ≥100–150 mg/dL, INR ≤1.5 — transfuse aggressively in the first 7–10 days, even before traditional thresholds.

Cross-references

• Cytogenetics Atlas — t(15;17), variant RARA fusions
• Drug Regimens — ATRA, ATO, GO dosing
• AML — parent topic
• DIC — APL coagulopathy
• Hyperleukocytosis (esp. microgranular variant)

相關題目

• Q-003 — AML — APL suspicion + DIC, timing of ATRA
• Q-005 — APL — variant translocation t(11;17) PLZF::RARA
• Q-006 — APL — differentiation syndrome management
• Q-007 — APL — high-risk vs low-risk Sanz stratification
• Q-092 — APL DIC — fibrinogen target
• Q-168 — Cryoprecipitate vs FFP for low fibrinogen
• Q-180 — APL with hyperleukocytosis — DS prophylaxis

Sources

Drafted from OpenEvidence query 2026-05-07; cross-checked against APL0406 final (JCO 2017) and AML17 (Lancet Oncol 2015).