Match each patient's clinical presentation with the most accurate description of the underlying pathophysiologic mechanism responsible for their condition.
- A 32-year-old woman presents with progressive fatigue and scleral icterus. Labs reveal hemoglobin 8.2 g/dL, reticulocytes 8%, and elevated indirect bilirubin. Smear shows numerous spherocytes. Direct antiglobulin test (DAT) is strongly positive.Production of IgG autoantibodies directed against red blood cell surface antigens, leading to macrophage-mediated extravascular hemolysis
- A 28-year-old man reports passing dark-colored urine, particularly upon waking, and recent abdominal pain. Flow cytometry of peripheral blood reveals a significant population of erythrocytes lacking CD55 and CD59 surface proteins.Acquired somatic mutation in the PIGA gene causing impaired synthesis of the glycosylphosphatidylinositol (GPI) anchor
- A 45-year-old woman is evaluated for new-onset petechiae and easy bruising but feels otherwise well. Labs show a platelet count of 12,000/μL with normal hemoglobin and leukocytes. Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are normal.Production of IgG autoantibodies targeting platelet membrane glycoproteins (e.g., GPIIb/IIIa), leading to accelerated destruction in the spleen
- A 39-year-old woman is brought to the emergency department with confusion and fever. Labs show hemoglobin 7.5 g/dL, platelets 18,000/μL, and elevated creatinine. Smear demonstrates numerous schistocytes. PT and aPTT are normal.Severe deficiency or autoantibody-mediated inhibition of the ADAMTS13 metalloproteinase
- A 65-year-old man in the intensive care unit with gram-negative sepsis begins bleeding persistently from venipuncture sites. Labs reveal a platelet count of 45,000/μL, prolonged PT and aPTT, and a fibrinogen level of 80 mg/dL.Systemic uncontrolled activation of the coagulation cascade resulting in widespread microvascular thrombosis and consumption of clotting factors
Answer
The correct matches align each clinical vignette with its definitive underlying pathophysiology: Autoimmune hemolytic anemia is caused by IgG autoantibodies against red blood cells; Paroxysmal nocturnal hemoglobinuria is caused by a PIGA mutation; Immune thrombocytopenia is caused by IgG against platelet glycoproteins; Thrombotic thrombocytopenic purpura is caused by ADAMTS13 deficiency; and Disseminated intravascular coagulation is caused by systemic coagulation cascade activation.
Each clinical scenario corresponds uniquely to one distinct pathophysiologic mechanism. Careful interpretation of the clinical history, physical findings, and diagnostic laboratory panels allows for accurate diagnosis and matching.
Step-by-Step Solution
Key Concept
Pathophysiology of common hematologic disorders including microangiopathic hemolytic anemias, autoimmune cytopenias, and consumptive coagulopathies.