- Description: a rare disorder caused by clonal proliferation of Langerhans cells (antigen-presenting cells)
- Epidemiology: peak incidence between 5 and 10 years
- Clinical features
- Bone: Painful, lytic “punched-out” lesions, esp. in the skull. Can cause “floating teeth.”
- Skin: Scaly, seborrheic-like rash.
- Endocrine: Diabetes Insipidus from pituitary stalk involvement.
- Other: Recurrent otitis media (mastoid involvement), pulmonary LCH (in adult smokers).
- Diagnostics
- Normal calcium levels
- X-ray: osteolytic lesions with or without marginal sclerosis
- Biopsy (confirmatory test): proliferation of Langerhans cells (polygonal cells with coffee bean-shaped nuclei and eosinophilic cytoplasm)
- Electron microscopy: Birbeck granules (tennis racket-shaped or rod-like structures) in the cytoplasm
- Immunohistochemistry: cells are positive for S100, CD1a, and/or CD207