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Histiocytic disorders

Langerhans cell histiocytosis

Also called: LCH · Langerhans-cell histiocytosis · histiocytosis X · eosinophilic granuloma · Hand-Schuller-Christian disease · Letterer-Siwe disease · Hand-Schüller-Christian disease · eosinophilic granuloma (historical phenotype names)

What a donor has to do with this

A transplant is not a standard part of treating this condition. It is used rarely, in particular situations, and most people diagnosed with it will not have one.

This is our reading of published transplant guidelines for this condition, not a measurement of how many people need a donor. Where a source actually counted donors, the figure and the people it counted are shown further down. Where none did, we say so rather than estimate.

This page is not written out in full yet

We have not written this condition out in full yet. What is on this page — how a donor fits in, who it affects, and the sources behind that — is researched and linked, but the plain-English explanation of the condition itself is still to come.

What the evidence says

Who it affects
Childhood populations summarized by NCI LCH PDQ, United States page reviewed 2025, had a median presentation age of 30 months; adult LCH also occurs.
Treatments other than a transplant
Risk- and organ-directed chemotherapy (commonly vinblastine plus prednisone), cladribine- or cytarabine-based salvage, and BRAF/MEK-targeted therapy for MAPK-pathway disease; transplant is confined to refractory high-risk multisystem disease.
If a transplant is used, the cells come from
Allogeneic bone marrow, peripheral blood stem cells and unrelated cord blood are documented; the dominant source is not reported in the opened disease-specific sources (international paediatric series and reviews, published 2015 and 2025).
How often the donor was unrelated
Not reported. No source we could read states this for this condition, so we do not give a number. An estimate here would be a guess dressed as evidence.

Where this gets complicated

Modern MAPK-targeted therapy has changed salvage practice; sources agree HCT is not routine for single-system or pulmonary LCH, but its place relative to prolonged targeted therapy in refractory high-risk multisystem disease remains unsettled.

Written for transplant clinicians, not for patients, in NCI LCH Treatment PDQ.. We quote it so you can see what the guidance actually says:
“HSCT has been used in patients with multisystem high–risk-organ involvement that is refractory to chemotherapy.”

It describes what teams consider in general. It cannot say what applies to any one person. Read the source.

Registries need people

An unrelated donor is not a usual part of treating this condition. Registering still matters, for the many conditions where it is.

Joining a registry is a cheek swab and a short health form. You are not matched to a condition — you are matched to a person, and it could be someone with any of the conditions in this library. You are contacted only if you turn out to be a possible match for someone, and you can ask questions and decline before anything else happens.

Find your registry

Related conditions

Others in histiocytic disorders. They are genuinely different diseases with different treatments — the group name is not a diagnosis.

Where this came from

Langerhans cell histiocytosis — what a bone marrow donor has to do with it | Jada Bascom Foundation