LANGERHAN CELL HISTIOCYTOSIS

Tennis Rackets

Langerhan cells are specialized macrophages that live in the skin. Their job is to be the first WBCs to spot pathogens invading the skin, then present their Ag to naive T cells. 

Langerhan Cell Histiocytosis is cancer of the Langerhan cells. There are a bunch of subtypes, and there’s seemingly a million details, but all you really need to know is what I bolded. This is a very buzzword-y disease. 

• Birbeck granules (random proteins shaped liked tennis rackets) seen on electron microscopy

• They express CD1+ and S100+

• They cause lytic bone lesions

• These are low yield, but here’s how to differentiate the different subtypes (big ups to Dr. Sattar)

  • • • If the disorder is named after someone, then it’s malignant. If it’s malignant, then there are skin symptoms (e.g., a rash)

      • If the disorder has 2 names separated by a hyphen, then it affects kids under 2 years old

      • If the disorder has 3 names separated by hyphens, then it affects kids over 3 years old

  • Letterer-Siwe Disease - malignant, rash, infants, fatal

  • Eosinophilic Granuloma - benign, pathologic fractures, adolescents

  • Hand-Schuller-Christian Disease - malignant, rash, lytic skull lesions, diabetes insipidus, exophthalmos, kids over 3 years old