Discussion of Eosinophilic granuloma
- Eosinophilic granuloma (EG) is the benign form of the 3 clinical variants of Langerhans cell histiocytosis, which include Letterer-Siwe disease, Hand-Schüller-Christian disease, and EG (formerly termed histiocytosis X).
- EG is characterized by a single or multiple skeletal lesions
- Predominantly affects children, adolescents, or young adults.
- Any bone can be involved, but the most common sites include the skull, mandible, spine, ribs, and long bones.
- Lesions usually begin to regress after approximately 3 months, but they may take as long as 2 years to resolve.
- The prognosis is usually excellent, with spontaneous resolution by fibrosis occurring within 1-2 years.
- In other instances, curettage, excision, or local irradiation leads to cure, although some authorities believe that the rate of spontaneous resolution of osseous and extraosseous lesions is unaffected by the mode of therapy.
- The male-to-female ratio is 3:2.
- Most patients have no symptoms, and the diagnosis is usually based on radiographic demonstration of a destructive bone lesion arising from the marrow cavity and on characteristic morphologic findings.
 Imaging Findings for Eosinophilic granuloma
- When tubular bones are involved, diaphyseal and metaphyseal localization is more frequent than epiphyseal localization. Epiphyseal lesions may cross the open physeal plate.
- The diploic space of the parietal and temporal bones are usually involved.
- Skull lesions are lytic, with a beveled edge or sharp and serrated margins and the absence of sclerosis in calvarial lesions.
- A hole-within-a-hole appearance may occur as a result of uneven erosion of the inner and outer tables of the skull.
- Mandibular lesions may be associated with gingival and soft tissue swelling and floating teeth.
- Ribs show lytic expansile lesions, which may be associated with pathologic fractures.
- Long bones below the knees and distal to the elbows are rarely involved.
- Lesions are lytic, round or oval, and expansile, with ill-defined or sclerotic margins.
- The medullary cavity may be expanded and associated with cortical thinning, intracortical tunneling, and erosion of the cortex and an adjacent soft-tissue mass.
- Laminated periosteal new bone formation is common around the involved segment of bone.
- Vertebral destruction may lead to flattening of the vertebral body, which is termed vertebra plana and is a finding that is much more common in children than in adults.
- Lung involvement is seen in as many as 20% of patients, with an incidence of 0.05-0.5 per 100,000 patients annually.
 See Also
 External Links
 References for Eosinophilic granuloma
- E-medicine Eosinophilic granuloma article.