Langerhans Cell Histiocytosis (LCH) is a rare disease that affects children and teenagers under 18. It involves an overgrowth of certain immune cells, which can lead to damage in various organs. The LCH-IV study is an international effort to improve treatment for kids with LCH. It uses a mix of medicines called vinblastine and prednisone to help treat this disease. The study divides patients into seven groups, or strata, based on their specific needs and treatment responses.

• The study may take up to a year, depending on the patient's response.
• Participants need to be under 18 and have a confirmed diagnosis of LCH.
• There will be regular check-ups to monitor progress and manage any side effects.

Before joining the study, parents or guardians must give permission, and patients should be aware of the potential risks and benefits. The study aims to personalize treatment to help prevent the disease from coming back and manage any long-term effects. This study is a chance to advance our understanding and improve care for LCH patients worldwide.