• • Histiocytic Disorders – over-production of histiocytes; wide group of diseases
    • Dendritic cell disorders (Langerhans cell histiocytosis)
    • Macrophage cell disorder (Rosai-Dorfman and hemophagocyticlymphohistiocytosis (HLH))
  • Rosai-Dorfman
    • Sinus Histiocytosis with massive lymphadenopathy
    • Presents in children with massive, nontender cervical adenopathy but can also include mediastinal and inguinal lymphadnopathy
    • Also involves pulmonary nodules, rash, lytic bone lesions, and fevers
    • Emperipolesis (engulfment of inflammatory cells by histiocytes) is a pathologic hallmark
    • Clofarabine (purine analog) has been used as treatment 
  
  

  Posted 04/18/17 10:17:03 AM by Ying Liu

• Hemophagocytic Lymphohistiocytosis (HLH)
  • Aggressive and life-threatening syndrome of excessive immune activation due to lack of normal downregulation of activated macrophages and lymphocytes
  • 3 Types:
    • Familial
    • Sporadic
    • Associated with rheumatological conditions (Macrophage Activating Syndrome)
  • Infection is a common trigger
  • Commonly viral such as EBV
  • Incidence of 1 child in 3000 admitted to a tertiary care pediatric hospital 
  
  

  Posted 04/18/17 10:17:49 AM by Ying Liu

• For further reading...

  http://www.bloodjournal.org/content/118/17/4577.long?sso-checked=true
  
  

  Posted 04/18/17 10:19:06 AM by Ying Liu

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