Match each clinical presentation with its most characteristic peripheral blood smear findi… — USMLE Step 2 CK

Match each clinical presentation with its most characteristic peripheral blood smear finding.

Routine preoperative laboratory testing for an asymptomatic 65-year-old man reveals a white blood cell count of $55,000/\mu L$ with marked lymphocytosis.Remnants of fragile lymphocytes lacking intact cytoplasm (Smudge cells)
During evaluation for progressive fatigue and gingival bleeding, a 40-year-old woman is found to have pancytopenia with a high fraction of circulating blasts.Linear, azurophilic cytoplasmic granules representing fused lysosomes (Auer rods)
Two days after initiating trimethoprim-sulfamethoxazole therapy, a 25-year-old man develops acute jaundice, dark urine, and a rapidly falling hemoglobin level.Erythrocytes with semicircular peripheral defects from splenic phagocytosis (Bite cells)
A rapid response is called for a 35-year-old woman who develops sudden-onset confusion, fever, acute kidney injury, and profound thrombocytopenia.Irregularly shaped, mechanically sheared erythrocytes lacking central pallor (Schistocytes)

Cevap

The asymptomatic older male with marked lymphocytosis matches with fragile leukocyte remnants (smudge cells). The patient with pancytopenia and circulating blasts matches with linear azurophilic granules (Auer rods). The young man with sulfa-induced hemolysis matches with semicircular erythrocyte defects (bite cells). The woman with confusion, fever, acute kidney injury, and thrombocytopenia matches with mechanically sheared erythrocytes (schistocytes).

Peripheral blood smear evaluation is critical for distinguishing hematologic pathologies. Smudge cells indicate the fragile monoclonal B-cells of CLL. Auer rods are pathognomonic for myeloblasts in AML. Bite cells indicate splenic phagocytosis of oxidized hemoglobin seen in G6PD deficiency. Schistocytes represent the mechanical destruction of erythrocytes characteristic of microangiopathic hemolytic anemias like TTP.

Adım Adım Çözüm

Evaluate the first vignette describing an asymptomatic elderly patient with significant incidental lymphocytosis.

Diagnose Chronic Lymphocytic Leukemia (CLL), which pairs with smudge cells due to the characteristic fragility of the malignant lymphocytes.

Identifying the classic demographic and lab presentation of CLL isolates its specific morphologic marker.

Analyze the second vignette featuring pancytopenia and circulating blasts in a middle-aged adult.

Diagnose Acute Myeloid Leukemia (AML), which pairs with Auer rods.

Auer rods are pathognomonic for myeloblasts in AML and help distinguish it from acute lymphoblastic leukemia (ALL).

Assess the third vignette involving acute hemolysis triggered by a sulfa antibiotic.

Diagnose Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency, which pairs with bite cells (degmacytes).

Sulfa drugs induce oxidative stress in G6PD deficiency, causing Heinz body formation; splenic removal of these bodies produces bite cells.

Examine the final vignette showing the classic pentad of fever, neurologic changes, renal failure, and thrombocytopenia.

Diagnose Thrombotic Thrombocytopenic Purpura (TTP), which pairs with schistocytes.

TTP is a microangiopathic hemolytic anemia (MAHA) where microthrombi shear red blood cells as they pass through small vessels.

Anahtar Kavram

Recognizing the pathognomonic peripheral blood smear findings associated with highly tested hematologic and oncologic disorders.

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