Multisystem LCH in Children Under 18: What to Do When Prednisolone and Vinblastine Fail to Resolve Risk Organ Involvement
Clinical Scenario
This protocol applies to patients under 18 years of age with multisystem Langerhans cell histiocytosis (MS-LCH) in the risk group — defined by involvement of at least one risk organ: the hematopoietic system, liver, and/or spleen.
Risk organ involvement may present as:
- Peripheral blood cytopenia (including bi- or pancytopenia)
- Hepatomegaly with organ dysfunction
- Splenomegaly
First-Line Treatment Did Not Work
Standard first-line therapy for risk-group MS-LCH — prednisolone combined with vinblastine, administered over up to 12 months — is intended to achieve resolution of risk organ involvement within 6–12 weeks of initiation.
This protocol is triggered when that goal was not reached: risk organ involvement persisted despite first-line therapy, placing the patient in a very high-risk category that requires a next-line approach.
Next-Line Approach (Partial Overview)
For very high-risk MS-LCH refractory to first-line therapy, salvage options involve chemotherapy-based combinations and — depending on patient-specific factors including molecular characteristics — transplant strategies or targeted interventions.
Regimen selection criteria, patient eligibility, and the full sequencing algorithm are contained in the complete structured protocol below.
References
- 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 curative potential of the combination of 2-CdA and Ara-C in patients with severe refractory to front-line systemic therapy multisystem LCH has been confirmed by two prospective trials.
- Allogeneic hematopoietic stem cell transplantation is another treatment option for very high-risk multisystem LCH with curative rate comparable to those achieved with 2-CdA and Ara-C.
- Currently published pediatric series show impressive rapid response to vemurafenib and prove that sustainable treatment effect can be achieved with BRAF inhibitors.
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