Histiocytic disorders happen when the body produces too many histiocytes, which are a type of white blood cell. When these cells build up, they can form rashes, lesions or tumors on the skin or organs. Severe cases of histiocytic disorders can cause organ damage.

There are several different types of histiocytic disorders. We classify the type of disease based on which kind of histiocyte the body is over-producing.

Our team at the Histiocytosis Center has expertise in diagnosing, treating and monitoring these rare conditions.

Langerhans Cell Histiocytosis (LCH)

Langerhans cell histiocytosis (LCH) is a condition where your body makes too many immature Langerhans cells. These cells are a type of histiocyte cell. When these cells build up, they can form tumors or damage tissue, bone and organs. LCH is the most common type of histiocytic disorder.

Juvenile Xanthogranuloma (JXG) Histiocytosis

Juvenile xanthogranuloma (JXG) is a type of non-Langerhans cell histiocytosis. JXG happens when the body makes too many macrophage-dendritic cells, which are a type of histiocyte cell. When the cells build up, they can cause symptoms like skin rashes (lesions).

JXG is usually benign and often affects infants and children under age 2. The lesions tend to appear on the skin of the head, neck or torso. In some cases, the lesions may also show up on the legs, arms, feet, eye, buttocks and rarely, within organs.

Rosai-Dorfman Disease (RDD)

Rosai-Dorfman disease (RDD) is another type of non-Langerhans histiocytosis. RDD happens when the body makes too many RDD histiocyte cells. The cells tend to build up in the lymph nodes, but can grow in other parts of the body. RDD is usually not life-threatening, but severe cases can sometimes lead to organ damage.

RDD is also called sinus histiocytosis with massive lymphadenopathy (SHML). It usually affects children under the age of 10 but can also sometimes occur in older children and adults.

ALK Histiocytosis

ALK histiocytosis is a histiocytic condition that's caused by a change in the ALK gene. Signs and symptoms of ALK histiocytosis are very similar to other histiocytic conditions, including JXG histiocytosis. The unique feature of this disease is that the patient has a gene fusion in the ALK gene.

Histiocytic Sarcoma (HS)

Histiocytic sarcoma (HS) is a blood-related cancer. It is a very rare type of non-Langerhans cell histiocytosis. It usually causes painful lumps in the lymph nodes, which are found in the neck, under the arms and around the groin. It can also sometimes cause abdominal pain if the disease affects the lymph nodes in the abdomen.

Another cancer-related condition is Langerhans cell sarcoma (LCS). LCS is a malignant tumor of Langerhans cells. It is rare in children, but it can sometimes occur at the same time or after leukemia.
Although typical sarcomas affect bone or connective tissue, HS and LCS are believed to be blood-related cancers that grow from malignant histiocyte cells. They were previously labeled as a sarcoma because the spindle-shaped cells of HS look similar to sarcoma cells.

Post-Leukemia / Lymphoma Histiocytic Lesions

Some children who have leukemia or lymphoma may also have a buildup of histiocyte cells that cause lesions. In some cases, these lesions have the same molecular changes as leukemia and lymphoma cells and can look similar under the microscope.

Pediatric Erdheim-Chester Disease (ECD)

Erdheim-Chester disease (ECD) is a type of non-Langerhans cell histiocytosis. It happens when the body creates too many histiocytes. In ECD, the histiocyte cells usually build up in specific locations in the body, including the long bones of the arms and legs, which causes bone pain. However, ECD can also affect the nervous system, heart, lungs, liver and the soft tissue around the eyes.

ECD is a very rare disease that usually affects adults. However, there are some cases of ECD in children. Children with ECD often have mutations in the BRAF gene. If left untreated, ECD can cause serious health problems in the lungs, heart and kidneys.