A Langerhans cell is a specific kind of white blood cell. Found largely in the epidermis, the outer layer of the skin, as well as in lymph nodes, Langerhans cells are an important element of the immune system. They are classified as dendritic cells because they grow projections called dendrites as they develop. Langerhans cells work to prevent infections, and they help trigger immune reactions by interacting with T-cells. The Langerhans cell, like other forms of white blood cells, is produced in the bone marrow.
Under normal conditions, Langerhans cells occur in small numbers, concentrated mostly in the skin, and respond to bacteria and other agents that occur on the skin's surface and can cause infection. In some cases, though, the body produces far too many of this specialized cell, leading to a rare condition called Langerhans cell histiocytosis (LCH). This condition leads to a variety of systematic symptoms and is often difficult to diagnose.
The symptoms and seriousness of Langerhans cell diseases are determined by where the proliferation of the Langerhans cell occurs. If the cells multiply and remain mostly in the skin, the result often is localized to the skin. This disorder occurs most often in younger children, so this can manifest as diaper rashes or other types of rash that do not respond to normal treatment. When the cells migrate to other parts of the body, the symptoms are much more widespread and serious, and the disorder can be life-threatening. Determining the presence of the Langerhans cell in major organs also can be difficult, often requiring biopsy and other complex diagnostic techniques.
LCH is classified as a histiocytosis, a term used to describe diseases that result from overproduction of white blood cells. Other histiocytoses include leukemia and lymphoma. While some doctors consider LCH to be a cancer-type disease because it results from abnormal proliferation of a cell, others consider it to be an autoimmune disorder. It occurs most often in children younger than 10 years old. Treatment varies based on the individual patient's condition, symptoms and age, and it can include steroid treatment as well as chemotherapy and radiation.
Another form of LCH, pulmonary LCH, occurs in adult smokers rather than in children. In this disorder, pulmonary Langerhans cells build up in the lungs, filling air spaces and other small open areas in the lung tissue. Treatment with steroids sometimes is utilized, but the most effective treatment for pulmonary LCH is to stop smoking. In advanced cases, lung transplant might be necessary.