Hemolytic Uremic Syndrome (HUS)

Epidemiology and Etiology:

• Thrombotic microangiopathy
• Overlapping features with Thrombotic Thrombocytopenic Purpura (TTP)
• Young children primarily
• Enteric infection by Shiga toxin-producing bacteria (E. coli 0157:H7 or Shigella) (D+HUS) (>90%)
• Develops 4-6 days after diarrhea onset usually
• Summer months more
• Shiga toxin causes endothelial cell death resulting in thrombus formation
• D-HUS (uncommon)
• No antecedent enteric infection with a Shiga toxin-producing organism)

Common sites:

• Kidneys preferentially involved

Gross features:

Histologic features:

• Kidney biopsy:
• Small vessel thrombi composed primarily of fibrin with few platelets and little vWF
• Endothelial damage pronounced in D+HUS
• Glomerular thrombosis (characteristic in D+HUS)

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

Other features:

• Diarrhea (often bloody)
• Vomiting
• Abdo pain
• Fever
• HTN
• Fits
• D-HUS has poor prognosis (25% mortality)

References:

• Porwit A, McCullough J, Erber WN. Blood and bone marrow pathology (2011)