Langerhans cell histiocytosis (LCH) is a rare disease affecting primarily young children. While LCH may heal by itself without treatment in some patients, others require intensive chemotherapy and suffer from long-term consequences, or may even succumb to the disease. The reasons for these differences in disease severity are poorly understood. In a new study published in Cancer Discovery, researchers from the St. Anna Children’s Cancer Research Institute (CCRI) and the CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences revealed important insights into the cellular heterogeneity and molecular mechanisms underlying LCH.