This protocol addresses first-line management of pulmonary Langerhans cell histiocytosis in paediatric patients (age under 18 years) who present with multisystem Langerhans cell histiocytosis and confirmed risk organ involvement — the hematopoietic system, liver, and/or spleen.
Multisystem LCH with risk organ involvement is defined by at least one of: peripheral blood cytopenia, hepatomegaly with or without organ dysfunction, or splenomegaly. This finding stratifies patients into a distinct risk group with a probability of survival of 80–90% — substantially lower than low-risk multisystem LCH. Children with bi- or pancytopenia and liver dysfunction who do not respond to early treatment carry a particularly poor prognosis (survival below 50%).
Front-line therapy combines a corticosteroid with a cytotoxic agent, delivered across an initial phase and a subsequent continuation phase. This combination represents the most extensively studied first-line approach in paediatric-onset LCH.
The primary clinical objective is response in risk organs — specifically, resolution of risk organ involvement — assessed after 6–12 weeks of initial treatment.
This document refers to Langerhans cell histiocytosis with onset in childhood and adolescence (age < 18 years).
Risk organ involvement at diagnosis (defined as at least one of the following: peripheral blood cytopenia and/or liver enlargement ± organ dysfunction and/or spleen enlargement) allows stratification of MS-LCH into low risk (probability of survival of nearly 100%) and risk group (probability of survival of 80–90%).
Patients with risk organ involvement (particularly those with bi-, pancytopenia and liver dysfunction), who do not respond to 6 weeks of standard treatment have particularly dismal prognosis (survival less than 50%).
The combination of prednisolone plus vinblastine is the most extensively studied first-line therapy in pediatric-onset LCH.
It consists of 6–12 weeks of initial therapy (oral steroids and weekly vinblastine injections), followed by a continuation therapy given to total treatment duration of 12 months.
The continuation therapy consists of prednisolone (day 1–5)/ vinblastine (day 1) pulses given every 3 weeks.
In ‘high-risk’ patients of the LCH-III trial, the prednisolone plus vinblastine combination has induced response in risk organs in 70% of the patients after 6–12 weeks of treatment, and resulted in an overall 5-year survival of 84%, and a reactivation-free survival of 73%.
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