Hypereosinophilic Syndrome

 

Epidemiology:

    • Whites > blacks
    • Men > women (9:1)
    • 20-50y

 

Common sites:

    • heart (>60%) (Loeffler endocarditis)
    • lungs
    • liver
    • spleen
    • nervous system
    • skin
    • may involve any organ

 

Gross features:

    • heart:
      • fibrous biventricular endocardial thickening
        • frequent extension to and involvement of mitral valve and its supporting structures
      • mural thrombi
      • cardiomegaly
        • ventricular hypertrophy
        • atrial enlargement
      • pericardial effusion

 

Histologic features:

    • eosinophils in tissue (any tissue)
    • tissue destruction
      • fibrosis
    • blood:
      • mature eosinophils
      • small numbers of eosinophilic myelocytes or promyelocytes
      • neutrophilia often
      • blasts infrequent or <2%
        • if above, consider eosinophilia secondary to leukemia
    • bone marrow:
      • hypercellular
      • eosinophilic proliferation
      • Charcot-Leyden crystals often
      • Normal erythropoiesis and megakaryocytopoiesis
      • Marrow fibrosis in some
    • heart:
      • earliest changes:
        • eosinophilic infiltrates in the myocardium
        • focal necrosis
      • mural thrombosis of the endocardium with infiltration by eosinophils
      • involvement of small intramural coronary vessels by fibrosis, thrombosis, and inflammatory cells
      • Endocardial and endothelial deposition of major basic protein (MBP), eosinophil peroxidase (EPO) and eosinophil cationic protein (ECP)
      • eosinophilic infiltration of the endocardium and myocardium (not in all cases)
      • diffuse fibrosis in late stage
    • nervous system:
      • peripheral neuropathies
      • infarcts (embolic)
    • skin:
      • dermal perivascular infiltrate of eosinophils and mononuclear cells
    • liver:
      • chronic active hepatitis
        • infiltration of portal triads by eosinophils

 

Immunophenotype:

Marker:

Sensitivity:

Specificity:

 

 

 

 

Molecular features:

    •  

 

Other features:

    • note: these pathologi cal and clinical features can occur in patients with eosinophilia from any cause
    • clinically:
      • >1500 eos/mm^3 for >6 mo.
      • Rule out all other causes
      • Signs or symptoms of organ infiltration by eosinophils
        • chronic congestive heart failure
        • mitral regurgitation
        • systemic embolization
        • cough & infiltrates
        • peripheral neuropathies
        • embolic strokes
        • global CNS dysfunction
    •  

 

References:

    • 2006