Examkin

Soru

Zorluk: ZorFormulating a Differential Diagnosis

A 34-year-old man presents to the emergency department with severe, acute-onset right upper quadrant abdominal pain and progressive abdominal swelling. Over the past six months, he has experienced recurrent episodes of profound fatigue and notes that his urine is occasionally dark red or brown, particularly when he wakes up in the morning. Two years ago, he was treated for a deep vein thrombosis in his left lower extremity following a long flight. Vital signs show a temperature of 37.2°C (99.0°F), blood pressure of 135/85 mm Hg, heart rate of 105/min, and respiratory rate of 18/min. Physical examination reveals scleral icterus, tender hepatomegaly, and moderate ascites.

Laboratory studies:
Hemoglobin: 8.8 g/dL
Reticulocyte count: 7.5%
Leukocyte count: 3,200/mm³
Platelet count: 105,000/mm³
Total bilirubin: 4.1 mg/dL
Direct bilirubin: 0.6 mg/dL
Lactate dehydrogenase (LDH): 1,600 U/L
Haptoglobin: 8 mg/dL (Normal: 41-165 mg/dL)
Prothrombin time: 13 sec
Activated partial thromboplastin time: 30 sec

Abdominal duplex ultrasonography reveals absent flow in the hepatic veins. Which of the following is the most likely diagnosis?

  1. Paroxysmal nocturnal hemoglobinuriaCevap
  2. B
    Factor V Leiden mutation
  3. C
    Autoimmune hemolytic anemia
  4. D
    Antiphospholipid syndrome
  5. E
    Acute intermittent porphyria

Cevap

The most likely diagnosis is paroxysmal nocturnal hemoglobinuria.
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic stem cell disorder characterized by a mutation in the PIGA gene, leading to an absence of glycosylphosphatidylinositol (GPI) anchor proteins (such as CD55 and CD59) on the surface of blood cells. This renders red blood cells highly susceptible to complement-mediated destruction, resulting in intravascular hemolysis (fatigue, dark morning urine due to hemoglobinuria, highly elevated LDH, low haptoglobin). The condition also affects platelets and leukocytes, leading to pancytopenia. Furthermore, the complement-mediated damage and release of free hemoglobin create a highly prothrombotic state, particularly in atypical locations such as the hepatic veins (Budd-Chiari syndrome), cerebral veins, and dermal vessels. The patient's triad of intravascular hemolysis, pancytopenia, and Budd-Chiari syndrome is classic for PNH.

Adım Adım Çözüm

1
Analyze the hematologic abnormalities.
The patient has pancytopenia (anemia, leukopenia, thrombocytopenia) along with markers of severe intravascular hemolysis (elevated LDH, low haptoglobin, indirect hyperbilirubinemia, and reticulocytosis).
Identifying the pattern of cellular deficiencies and hemolysis is critical for narrowing the differential diagnosis.
2
Evaluate the clinical presentation and imaging findings.
The patient has a history of unprovoked deep vein thrombosis and now presents with acute Budd-Chiari syndrome (hepatic vein thrombosis), indicated by right upper quadrant pain, hepatomegaly, ascites, and absent flow on Doppler ultrasound.
Connecting the hematologic findings with the thrombotic events defines the syndromic presentation.
3
Synthesize the findings to formulate the most likely diagnosis.
The combination of acquired intravascular hemolysis, pancytopenia, and atypical venous thrombosis (Budd-Chiari syndrome) strongly points to paroxysmal nocturnal hemoglobinuria.
PNH is caused by an acquired mutation in the PIGA gene, leading to a lack of GPI-anchored proteins on blood cells, making them susceptible to complement-mediated destruction and promoting a prothrombotic state.

Anahtar Kavram

Paroxysmal nocturnal hemoglobinuria (PNH) presents with the classic triad of intravascular hemolysis, atypical venous thrombosis, and cytopenias.
Bu soruyu puanla

Konular

Formulating a Differential Diagnosis

Bu konudan daha fazla soru