Acute Promyelocytic Leukemia (APL)

Acute promyelocytic leukemia (APL) is a special subtype of AML, classified as FAB M3. Improved cell-biology understanding and treatment have greatly improved outcomes and reduced early mortality. Clinically not rare; patients relatively young (median 30-38y); <10y rare. Chinese data: M3 ~10% higher than Western (~18.7% of concurrent AML); up to 20-30% in Northeast oilfields. European/Latin-American higher; APL ~10-15% of adult primary AML.

Common Symptoms

Lymph-node enlargement; bleeding tendency; bone pain; intravascular coagulation

Causes and Pathogenesis

Primary APL etiology unknown; secondary after chemo/radiation (alkylating agents/topoisomerase-II inhibitors); secondary APL prognosis similar to primary. APL is differentiation-therapy responsive (RARalpha fusion protein). 5 translocations all involve RARalpha (chr17q21, 39398bp, 9 exons). t(15;17) = PML-RARalpha in vast majority. PML: nuclear protein (proline-rich, cysteine-rich, coiled-coil, NLS); normally in PODs (15-20 nuclear bodies); growth-suppressor/apoptosis. t(15;17)(q22;q21): (i) dominant-negative inhibition of promyelocyte maturation; (ii) PML delocalization, POD destruction; (iii) RARalpha binds N-CoR/Sin3a/HDAC-1; PML-RARalpha enhances co-repressor binding → blocks differentiation; ATRA degrades PML-RARalpha, releases co-repressors, recruits CBP/P300/P/CAF/NCoA-1/SRC-1 → histone acetylation → differentiation. Variant t(11;17)(q23;q21) PLZF-RARalpha + RARalpha-PLZF (ATRA-resistant); t(5;17) NPM-RARalpha; t(11;17)(q13;q21) NuMA-RARalpha; dup(17) STAT5b-RARalpha. Transgenic mouse models confirm leukemogenicity.

Treatment

Drug, supportive therapy

Preventive Measures

(1) Avoid excessive X-rays/radiation. (2) Don't abuse chloramphenicol/cytotoxic/immunosuppressants. (3) High-protein/high-fiber/high-calorie; fresh produce; avoid greasy/raw/cold/spicy; meat:veg ratio 3:7; limit processed meats. (4) Avoid benzene/formaldehyde/radon (new renovation; ventilate; air purifiers/active carbon/spider plants/pothos). (5) Sleep on time; melatonin suppressed by night light → cancer risk.

Department to Visit

It is recommended to visit the Hematology department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.