Hemophagocytic syndrome

Hemophagocytic syndrome
Diagnosis in short
Micrograph showing phagocytosed RBCs in hemophagocytic syndrome. H&E stain.
LM	macrophages containing erythrocytes (red blood cells), leukocytes, platelets
Subtypes	primary, secondary
LM DDx	overlapping cells, emperipolesis
Molecular	primary form: FHL1 mutation or FHL2 mutation; autosomal recessive
Site	lymph nodes, liver, spleen, bone marrow, others
Associated Dx	only in secondary form (EBV infection, malignancy, rheumatologic disease)
Clinical history	+/-consanguinity for primary form
Signs	fever, splenomegaly, jaundice
Prevalence	rare
Prognosis	dependent on underlying cause

Hemophagocytic syndrome, also known as hemophagocytic lymphohistiocytosis, is a rare condition often associated with viral infections.

Clinical

Features:

• Fever.
• Splenomegaly.
• Jaundice.

Involved organs:

• Lymph nodes.
• Liver.
• Spleen.
• Bone marrow.

Classification

Classified by etiology:

1. Primary, i.e. inherited:
   • Etiology: dysfunction of cytotoxic T lymphocytes with macrophage activating cytokines.
   • Autosomal recessive.
   • Two genes identified:
     • FHL1.
     • FHL2.
2. Secondary:
   • Infection, e.g. EBV (most common infectious etiology), HIV.
   • Malignancy.
   • Rheumatologic condition.

Microscopic

Features:

• Macrophages with phagocytosed:
  • Erythrocytes.
  • Leukocytes.
  • Platelets.

DDx:

• Overlapping cells (red blood cells overlapping macrophages).
• Emperipolesis in the context of other pathology.

Images

• 

  Hemophagocytic syndrome - cropped - very high mag. (WC)

• 

  Hemophagocytic syndrome - very high mag. (WC)

• 

  HLH (WC)

www:

• Hemophagocytic syndrome - several images (upmc.edu).

See also

• Hematopathology.
• Myospherulosis.
• Emperipolesis.