Histiocytosis: Symptoms, Types & Treatment

Histiocytosis is a rare condition in which too many histiocytes build up in the body. Histiocytes are specialized immune cells, and this buildup can lead to symptoms like skin lesions, headache, fever, and unexplained weight loss.

There are different forms of histiocytosis, based on where these cells collect. Examples include Langerhans cell histiocytosis, Erdheim-Chester disease, and Rosai-Dorfman disease.

In some cases, histiocytosis may resolve on its own, but its course can vary depending on the specific type and how extensively it affects the body. Diagnosis and treatment should always be managed by a doctor and may involve medications, chemotherapy or radiation therapy, surgery, or, in certain cases, transplantation.

Main symptoms

The main symptoms of histiocytosis are:

• Fever;

• Unexplained weight loss;

• Loss of appetite;

• Extreme fatigue;

• Swollen lymph nodes, especially in the neck;

• Spontaneous fractures and bone pain;

• Skin rashes;

• Lesions on the gums and teeth.

Depending on which organs and tissues are affected and how severe the damage is, histiocytosis may also cause hard-to-treat seborrheic dermatitis, skin tumors, headache, dizziness, seizures, and cognitive decline.

In addition, a person with histiocytosis may have vision problems, cough, chest pain or tightness, anemia, and yellowing of the skin and eyes, for example.

Histiocytosis can cause no symptoms at all, or symptoms can appear quickly. Symptoms can also vary depending on where the histiocytes are collecting.

Histiocytosis most often affects the bones, skin, liver, and lungs, especially in people with a history of smoking. Less often, it may involve the central nervous system, lymph nodes, gastrointestinal tract, and thyroid.

Is histiocytosis cancer?

Histiocytosis is not classified as cancer. It is a group of rare diseases or syndromes involving abnormal growth and buildup of histiocytes, which are specialized immune system cells.

Even though histiocytosis is not cancer, it can sometimes behave in ways that resemble cancer. For example, it may cause symptoms and organ involvement that can look similar to cancer.

Types of histiocytosis

The main types of histiocytosis are:

1. Langerhans cell histiocytosis

Also called histiocytosis X, Langerhans cell histiocytosis is the most common type of histiocytosis.

It is more common in children, with most cases diagnosed between ages 1 and 4. However, it can also occur in adults.

Langerhans cell histiocytosis may affect only one area of the body, and bone is the most common site. It can also affect two or more organs or body systems, which is more likely in younger children, especially infants.

2. Erdheim-Chester disease

Erdheim-Chester disease is a rare type of histiocytosis that mainly affects adults.

It can involve multiple areas of the body, including long bones (such as the bones in the legs), the eyes, the central nervous system, the lungs, the heart, the kidneys, and blood vessels.

3. Rosai-Dorfman disease

Rosai-Dorfman disease, also known as sinus histiocytosis, is another rare type of histiocytosis. Although it mainly affects children, it can also occur in adults.

It mainly causes swollen lymph nodes, especially in the neck, and may also affect the skin and bones.

Confirming a diagnosis

Histiocytosis may be diagnosed by a primary care provider, pediatrician, or hematologist through a physical exam and review of personal and family medical history.

To confirm histiocytosis and identify the specific type, a biopsy may be needed to remove cells or tissue from an affected site so it can be examined under a microscope, according to the National Cancer Institute (NCI). 

Other tests may also be used to support the diagnosis, such as a bone scan, ultrasound, computed tomography (CT) scan, mutation testing (such as BRAF), and a complete blood count.

Possible causes

Histiocytosis refers to a group of syndromes marked by an abnormal increase in histiocytes. These are specialized immune cells that include monocytes, macrophages, and dendritic cells, including Langerhans cells.

The exact cause of histiocytosis is still unknown. However, it is believed to be linked to genetic problems in immune system cells.

Factors that may increase the risk of histiocytosis include smoking, exposure to certain chemicals (such as solvents), exposure to metals, granite, or wood dust, and having a family history.

Treatment options

Treatment depends on how widespread the disease is and which areas are affected, and it may include:

• Chemotherapy;

• Radiation therapy;

• Medications such as corticosteroids, antibiotics, and immunosuppressants;

• Surgery, especially when bones are affected;

• Transplantation, such as liver transplant or stem cell transplant, for example.

Histiocytosis can be curable, especially when the disease is low-risk or limited to one area.

According to the National Cancer Institute (NCI), histiocytosis can sometimes recur or reactivate after treatment. For this reason, long-term follow-up and monitoring are recommended, even after therapy ends, to check for any signs of the disease returning.