Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Cancer Health Center

Font Size

Langerhans Cell Histiocytosis Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Histopathologic, Immunologic, and Cytogenetic Characteristics of LCH



The etiology of LCH is unknown. Efforts to define a viral cause have not been successful.[11,12] One study has shown that 1% of patients have a positive family history for LCH.[13]

Cytogenetic and Genomic Studies

Studies showing clonality in LCH using polymorphisms of methylation-specific restriction enzyme sites on the X-chromosome regions coding for the human androgen receptor, DXS255, PGK, and HPRT were published in 1994.[14,15] Biopsies of lesions with single-system or multisystem disease were found to have a proliferation of LCH cells from a single clone. Pulmonary LCH in adults is usually nonclonal and it is possible that this group represents a reactive process to smoking.[16] Cytogenetic abnormalities in LCH have rarely been reported. One study described an abnormal clone t(7;12)(q11.2;p13) from a vertebral lesion of one patient.[17] This study also reported nonclonal karyotypic abnormalities in three patients. An increase in chromosomal breakage was also noted.

Figure courtesy of Rikhia Chakraborty, Ph.D. Permission to reuse the figure in any form must be obtained directly from Dr. Chakraborty.

An activating mutation of the BRAF oncogene (V600E) was detected in 35 of 61 (57%) LCH biopsy samples, with mutations being more common in patients younger than 10 years (76%) than in patients aged 10 years and older (44%).[18] A subsequent study with a larger sample size did not confirm this association.[19] The RAS signaling pathway (Figure) transmits signals from a cell surface receptor (e.g., a growth factor) through the RAS pathway (via one of the RAF proteins [A, B, or C]) to phosphorylate MEK and then ERK, which leads to nuclear signals affecting cell cycle and transcription regulation. The V600E mutation of BRAF leads to continuous phosphorylation, and thus activation, of MEK and ERK without the need for an external signal.

The RAS pathway was activated in a few samples that were tested for MEK and ERK expression, whether or not the BRAF V600E mutation was present. The BRAF V600E mutation in LCH has been demonstrated in flow-sorted CD1a-positive LCH cells from fresh lesions in 11 of 16 samples.[20] Another BRAF mutation (BRAF 600DLAT) was identified that resulted in the insertion of four amino acids and that also appeared to activate MAPK pathway signaling.[20] No clinical characteristics associated with the BRAF mutation have been identified.[18,19,20]

Next Article:

Today on WebMD

Colorectal cancer cells
New! I AM Not Cancer Facebook Group
Lung cancer xray
See it in pictures, plus read the facts.
sauteed cherry tomatoes
Fight cancer one plate at a time.
Ovarian cancer illustration
Real Cancer Perspectives
Jennifer Goodman Linn self-portrait
what is your cancer risk
colorectal cancer treatment advances
breast cancer overview slideshow
prostate cancer overview
lung cancer overview slideshow
ovarian cancer overview slideshow
Actor Michael Douglas