Episode Details

Emergencies happen in hematology and oncology. This is a fact. But how do we manage these emergencies? Look no further.

In this episode, we’ll talk about one of the key hematologic malignancies that you’ll encounter as a fellow, one that requires immediate action to reduce mortality: acute promyelocytic leukemia (APL or APML)

- Acute Promyelocytic leukemia (APL or APML):

**Stay tuned for our upcoming “part two” and “chemotherapy basics” episodes for more information on non-acute management of this disease

**APL is a true hematologic emergency! Although this is a very curable form of leukemia, it is associated with high rates of severe DIC and high mortality in the period immediately following diagnosis

***Untreated, can see pulmonary or cerebrovascular hemorrhage in up to 40% of patients

***10-20% incidence of hemorrhage-related mortality in the initial period

***Statistically significant increase in mortality at 30 days with just a 12-hour delay in initial hematologist consultation

- Disease basics:

** Rare subtype of AML( <10% of cases)

** Driven by translocations involving the retinoic acid receptor alpha (RARA) on chromosome 17, classically with the promelocytic leukemia gene (PML) on chromosome 15 [i.e. t(15;17)]

***Other non-classical translocations exist, but nearly all involve RARA

**Because of this driver mutation, treatment with a specific isoform of vitamin A: all-trans retinoic acid (ATRA) forces promyelocytes to differentiate and ultimately apoptose 

- Initial work up:

**Standard CBC with differential, CMP

** Review smear for characteristic features:

** Large nuclei and scant cytoplasm

** “Folded” appearance to nuclei (like a peach emoji 🍑)

** Auer rods (which tells you blasts are myeloid lineage)

** Heavily granulated cytoplasm (hypergranular form - most common)

***Also a “hypogranular variant,” so like always, make sure to discuss any findings with your friendly neighborhood hematopathologist

**Stat DIC labs:

**PT/aPTT

**Fibrinogen

**Stat PML-RARA FISH (see next section) to look for classic driver mutation and clinch diagnosis

** “Tumor lysis syndrome (TLS) labs”

***LDH

*** Uric acid

**Peripheral flow cytometry

***CD33+, CD 117+

***CD34-, HLA-DR-, CD11a/b/c-

*** Increased side scatter (esp in hypergranular type)

- Acute Management

** Start ATRA: immediate treatment is so important in this disease, and side effect profile is minimal enough that empiric treatment when disease is on the differential is standard of c