Eosinophilic granuloma of the bone is a rare, noncancerous tumor that tends to affect children. It’s part of a spectrum of rare diseases, known as Langerhans cell histiocytosis, involving the overproduction of Langerhans cells, which are part of your immune system.

Langerhans cells are found in the outer layer of your skin and other tissues. Their function is to detect the presence of disease organisms and communicate that information to other immune system cells.

Eosinophilic granuloma most commonly shows up in the skull, legs, ribs, pelvis, and spine. In some cases, it can affect more than one bone.

The most common symptoms of eosinophilic granuloma are pain, tenderness, and swelling around the affected bone.

Other possible symptoms include:

  • headache
  • back or neck pain
  • fever
  • high white blood cell count (also called leukocytosis)
  • skin rash
  • difficulty bearing weight
  • limited range of motion

Fifty percent of cases of eosinophilic granuloma occur in one the bones that make up the skull. Other commonly affected bones include the jaw, hip, upper arm, shoulder blade, and ribs.

Researchers aren’t sure about what causes eosinophilic granuloma. However, it seems to be related to a specific gene mutation. This mutation is somatic, meaning it occurs after conception and can’t be passed on to future generations.

Eosinophilic granuloma is usually diagnosed with an X-ray or CT scan of the affected area. Depending on what the image shows, you may need to have a bone lesion biopsy done. This involves taking a small sample of bone tissue from the affected area and looking at it under a microscope. In some cases, children may need general anesthesia before a biopsy.

Many cases of eosinophilic granuloma eventually clear up on their own, but there’s no standard timeline for how long this could take. In the meantime, corticosteroid injections can help with the pain.

In rare cases, the tumor may need to be either partially or completely removed with surgery.

In some cases, eosinophilic granuloma can spread to multiple bones or to lymph nodes. If the tumor is particularly large, it can also cause bone fractures. When eosinophilic granuloma affects the spine, this can lead to a collapsed vertebra.

While eosinophilic granuloma can be a painful condition, it often resolves on its own without treatment. In other cases, corticosteroid injections can help to manage the pain. If the tumor becomes too large, it may need to be surgically removed.