Figure 3.

Treatment algorithm for adult Langerhans cell histiocytosis (LCH). Diagnosis of LCH is based on histological and immunophenotypic examination. The primary indicators are characteristic LCH cells and positivity for CD1a and/or Langerin (CD207) cells. Confirmation of cytoplasmic Birbeck granules by electron microscopy is no longer necessary. Complete patient history, including smoking history, must be determined, and specific physical examinations should be carried out, including neurological evaluation of central nervous system (CNS) and peripheral nerves. *In certain situations, such as involvement in vertebra or tissues near sensory organs, systemic therapy is recommended. **Involvement in craniofacial bones, eyes, ears, and oral cavity. MS, multisystem; PLCH, pulmonary LCH; SS, single system