• Lytic skull lesion differential: skeletal mets, MM, Langerhans, Paget’s, osteomyelitis, sarcoidosis, hemangioma
  
  

  Posted 05/29/16 03:46:24 PM by Matthew Cummings

• Langerhans’ cell histiocytosis: monocytic malignancy derived from myeloid dendritic cells --> distinct from pulmonary Langerhans’ in smokers who often present with cystic lung disease/spontaneous pneumothorax
  • Single-system disease occurs in >50% cases: bone>skin>LN>liver>pituitary (DI)
  • Multi-system disease often presents w/ constitutional symptoms and other organ-specific manifestations (assess extent with close skin exam, skeletal survey, CT chest, +/- MRI brain for pituitary)
  • Hand-Schuller-Christian: exophthalmos, lytic bone lesions, DI
  • Letterer-Siwe: constitutional symptoms, rash, anemia, hepatosplenomegaly 
  
  

  Posted 05/29/16 03:48:07 PM by Matthew Cummings

• Typically want tissue for dx (skin/bone/liver), rule out other malignancies/osteomyelitis
  • Histology: Sheets of histiocytes with eosinophils, +CD68 (monocyte marker), +CD1a and Langerin (Birbeck granules); ~50% BRAF mutations 
  
  

  Posted 05/29/16 03:48:27 PM by Matthew Cummings

• Limited evidence to guide therapy, but generally:
  • Localized disease = localized therapy (surgery, radiation), can be curative (calvarial lesions challenging, difficult to get clean margins so often combine surgery + radiation)
  • Systemic disease = chemotherapy, usually MTX, vinblastine/etoposide, steroids, some evidence for BRAF inhibition (vemurafenib)
  
  

  Posted 05/29/16 03:48:52 PM by Matthew Cummings

• For further reading...

  Langerhans' cell histiocytosis: diagnostic and therapeutic recommendations
  2014 update on pathogensis and treatment of Langerhans' cell histiocytosis
  Vemurafenib in multiple nonmelanoma cancers with BRAF V600 mutations (NEJM 2015)
  
  

  Posted 05/29/16 03:52:22 PM by Matthew Cummings

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