A 34-year-old woman is evaluated in the emergency department for a 2-day history of heavy … — USMLE Step 2 CK

A $34$ -year-old woman is evaluated in the emergency department for a $2$ -day history of heavy gingival bleeding, recurrent epistaxis, and a large bruise on her thigh after minor trauma. Her temperature is $37.9^\circ\text{C}$ ( $100.2^\circ\text{F}$ ), pulse is $112/\text{min}$ , and blood pressure is $105/65 \text{ mm Hg}$ . Physical examination reveals pallor, diffuse petechiae over the chest and extremities, and continuous oozing of blood from the intravenous line insertion site. Laboratory studies show:

Test	Value	Normal Range
Hemoglobin	$7.8 \text{ g/dL}$	$12.0-15.5 \text{ g/dL}$
Platelet count	$18,000/\text{mm}^3$	$150,000-400,000/\text{mm}^3$
Leukocyte count	$32,000/\text{mm}^3$	$4,500-11,000/\text{mm}^3$
Prothrombin time	$21 \text{ sec}$	$11-15 \text{ sec}$
aPTT	$45 \text{ sec}$	$25-40 \text{ sec}$
Fibrinogen	$80 \text{ mg/dL}$	$200-400 \text{ mg/dL}$

A peripheral blood smear demonstrates numerous atypical mononuclear cells with folded nuclei, heavily granulated cytoplasm, and bundles of rod-shaped cytoplasmic inclusions.

Arrange the following management steps in the most appropriate chronological sequence for this patient.

1Administer all-trans retinoic acid (ATRA)
2Perform bone marrow aspiration and biopsy
3Obtain molecular confirmation of the PML-RARA fusion
4Initiate definitive induction therapy with arsenic trioxide

Cevap

The correct sequence is: Administer all-trans retinoic acid (ATRA) -> Perform bone marrow aspiration and biopsy -> Obtain molecular confirmation of the PML-RARA fusion -> Initiate definitive induction therapy with arsenic trioxide.

The presentation of pancytopenia, severe coagulopathy (prolonged PT/aPTT, low fibrinogen), and a peripheral smear showing atypical cells with prominent bundles of Auer rods (faggot cells) is the classic manifestation of Acute Promyelocytic Leukemia (APL) complicated by disseminated intravascular coagulation (DIC). Because this coagulopathy can rapidly lead to fatal hemorrhage, the absolute first step in management is the immediate administration of all-trans retinoic acid (ATRA). This decision must be based purely on clinical and morphologic suspicion. ATRA forces the differentiation of leukemic promyelocytes into mature neutrophils, rapidly improving the coagulopathy. Once ATRA is administered and the patient's bleeding diathesis is acutely managed (often with cryoprecipitate, fresh frozen plasma, and platelets), a bone marrow aspiration and biopsy should be performed to secure the diagnostic material. The samples obtained are then sent for cytogenetic or molecular testing to confirm the presence of the

\text{t}(15;17)

translocation, which creates the PML-RARA fusion protein. Finally, once the diagnosis is definitively confirmed, combination induction therapy (often incorporating arsenic trioxide and/or an anthracycline alongside ATRA) is initiated to achieve complete remission.

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Analyze the clinical presentation and laboratory findings.

The patient has pancytopenia, clinical signs of disseminated intravascular coagulation (DIC), and atypical cells with bundles of Auer rods (faggot cells).

These findings are highly specific for Acute Promyelocytic Leukemia (APL), a medical emergency driven by the PML-RARA fusion protein.

Determine the most urgent, life-saving intervention.

Administration of all-trans retinoic acid (ATRA) is the immediate priority.

APL causes severe DIC leading to a high rate of early hemorrhagic death. ATRA induces differentiation of leukemic promyelocytes, rapidly resolving the coagulopathy, and must not be delayed.

Sequence the diagnostic and definitive treatment steps following initial stabilization.

Bone marrow biopsy is followed by molecular testing, which is then followed by targeted combination therapy.

Tissue acquisition must precede molecular confirmation. Once the specific genetic lesion is confirmed, final chemotherapeutic adjustments (such as adding arsenic trioxide) are made.

Anahtar Kavram

In patients with suspected Acute Promyelocytic Leukemia (APL) presenting with severe coagulopathy, all-trans retinoic acid (ATRA) must be administered immediately based on clinical suspicion, prior to bone marrow biopsy and molecular confirmation, to prevent fatal hemorrhage.

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