Langerhans cell histiocytosis (LCH) in children — a clear explanation for parents

To understand LCH, it helps to know what a Langerhans cell normally does. Langerhans cells are a type of immune cell that live in the skin and in the lining of the airways, gut, and other body surfaces. Their job is to act as sentinels — they detect foreign particles and alert the rest of the immune system. In Langerhans cell histiocytosis, these cells develop a genetic change (most commonly in a gene called BRAF) that causes them to multiply out of control and collect in one or more tissues. The word “histiocytosis” simply means an abnormal accumulation of histiocytes, which are a family of immune cells that includes Langerhans cells.

The BRAF mutation — the same mutation found in some melanomas and other cancers — is present in a large proportion of LCH cases. This discovery, made within the last two decades, has been important: it confirmed that LCH is a neoplastic (cancer-like) condition rather than an inflammatory reaction, and it opened the door to targeted therapies in difficult cases. Because of this, LCH is now managed within paediatric oncology departments at specialist centres, even though it is quite different from what most people picture when they hear the word “cancer.”

LCH can affect children of any age, but the peak incidence is in young children between one and three years old. It can also occur in older children, adolescents, and adults, though the pattern of disease can differ across age groups. The condition affects various parts of the body, including bones (most commonly the skull and other flat bones), skin, lymph nodes, the pituitary gland (a small gland at the base of the brain that controls hormone production), the liver, spleen, bone marrow, and less commonly the lungs. In some children, only a single area is affected; in others, the disease is widespread at diagnosis.

LCH is not caused by anything the parents did. It does not run strongly in families. It is not infectious. The genetic change in the Langerhans cells happens by chance within the child’s body, not because of any exposure, diet, or environmental factor that the family could have prevented or controlled.

LCH is not a single disease with a single course. The most important factor in planning treatment is understanding how widely it has spread and which organs it has reached. These are the classifications your child’s oncology team will use.

These classifications guide treatment planning. Your child’s exact classification will be determined after biopsy, blood tests, and imaging. The oncology team will explain what this means for your child in detail. — Back to the Paediatric Cancer Hub

One of the challenges with LCH is that its signs closely mimic those of far more common conditions. This can mean it takes time — sometimes months — from the first symptom to the correct diagnosis. The signs depend on which part of the body is affected.

Bone pain and swelling — The most common sign of LCH is a painful lump or swelling in a bone, most often in the skull. A parent may notice a tender raised area on the child’s head, or the child may begin protecting a limb or complaining of ongoing bone pain. Skull lesions are sometimes found when a parent feels an unusual bump while washing the child’s hair. Bone involvement in the spine can rarely cause back pain or, in serious cases, contribute to spinal instability; bone disease in the orbit (eye socket) can cause one eye to appear to protrude or “bulge.”

Ear symptoms — LCH in the bone behind the ear (the mastoid) or in the ear canal can cause chronic ear pain, discharge from the ear, or hearing loss that does not improve with the antibiotic courses typically used for ear infections. This is a commonly missed presentation in young children.

Skin changes — LCH affecting the skin may appear as a persistent scaly or greasy rash in areas where seborrhoeic dermatitis normally occurs — the scalp, behind the ears, in skin folds, and in the nappy area in infants. It can also present as small raised red-brown or yellow-brown spots. Unlike eczema or cradle cap, LCH skin involvement does not respond to standard topical treatments, which is an important clue.

Excessive thirst and urination — When LCH affects the pituitary gland (the small gland at the base of the brain), it can damage the cells that produce a hormone called ADH (antidiuretic hormone), which controls how much water the body retains. Without enough ADH, the child passes very large amounts of dilute urine and drinks enormous amounts of water. This condition is called central diabetes insipidus and is one of the more significant complications of LCH. It is not the same as diabetes mellitus (the familiar blood-sugar condition) and does not involve blood sugar at all. Diabetes insipidus caused by LCH may be permanent even after the LCH itself has been treated.

Swollen lymph nodes, liver, or spleen — In multi-system disease, the lymph nodes may be visibly enlarged, or the liver and spleen may be enlarged enough to cause a noticeably distended abdomen. Blood tests may show that the liver is not functioning normally.

Teeth and gums — In older children, LCH in the jawbone can cause loose teeth, bleeding gums, or a mass in the gum tissue. This is sometimes first noticed by a dentist.

General symptoms — Children with more widespread disease may also have persistent unexplained fever, significant weight loss, or a general failure to gain weight and grow as expected.

At CION, every child suspected of having LCH goes through a carefully structured evaluation before any treatment is proposed. Here is what the journey typically looks like.

Your child deserves a team that takes its time

17 oncologists. 35+ centres. A tumour board for every child. 45-minute consultations where we listen first — and every decision is made for healing, not billing.

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