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Eosinophilic granuloma (EG) is the benign form of Langerhans Cell Histiocytosis (LCH), a multisystemic rare disorder of unknown aetiology, mainly affecting male children, characterised by the proliferation of Langerhans cells.

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EG usually presents as a single skeletal lesion, often involving flat bones, with the skull being affected in more than 50% of the cases.

Spectrum of Langerhans cell histiocytosis (LCH):

Form	Description
Eosinophilic granuloma	Solitary or multifocal bone lesions
Hand–Schüller–Christian disease	Chronic, triad of skull lesions, diabetes insipidus, exophthalmos
Letterer–Siwe disease	Acute disseminated multisystem disease in infants (worst prognosis)

Epidemiology

Feature	Details
Age	Typically 5–20 years; peak in childhood
Sex	Slight male predominance
Sites	Skull (most common), mandible, spine, ribs, pelvis, long bones

Clinical Presentation

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EG is characterised by fever, localised pain, soft tissue swelling and mild peripheral eosinophilia, and it usually shows a benign clinical course, also considering its high sensitivity to radiation therapy

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Manifestation	Notes
Bone pain	Most common symptom, localized tenderness
Swelling	Over affected site
Fracture	Especially in vertebral lesions ("vertebra plana")
Neurologic symptoms	Possible in spinal or skull base lesions
Systemic symptoms	Rare in isolated EG; more common in multisystem LCH

Radiology

https://doi.org/10.1186/s13018-019-1158-1

https://doi.org/10.1016/j.radcr.2022.08.024

Plain Radiograph

Site	Appearance
Skull	Lytic lesion with bevelled edges due to asymmetric inner and outer table destruction
Mandible	"Floating tooth" appearance due to alveolar bone loss
Long bones	Central diaphyseal lytic lesion ± periosteal reaction
Spine	Vertebra plana – complete collapse of vertebral body with preserved disc space
Ribs/Pelvis	Lytic lesion ± cortical breakthrough

Cross-sectional imaging:

Modality	Imaging features
CT	• Excellent for cortical destruction
• Helps delineate skull or facial bone involvement
• Detects sequestrum or associated soft tissue component
MR	• T1: Iso- to hypointense lesion in marrow
• T2: Hyperintense lesion, often with soft tissue extension
• Post-contrast: Enhancing soft tissue mass; adjacent bone marrow enhancement
• Spine: Vertebral body collapse with normal disc height and paravertebral soft tissue
Nuclear imaging	• Bone scan: Increased uptake at active lesion sites
• FDG-PET/CT: Useful in multifocal or systemic disease

![Three-year-old female presenting with multiple tumors of the skull. a In the plain radiography, map like bone destruction (arrow). b Axial post-contrast computed tomography (CT) in bone window showed an aggressive lytic lesion with no peripheral sclerosis (arrow). c T2-weighted high signal is demonstrated in bilateral parietal bone (arrow). d Axial enhanced-contrast T1-weighted MRI showed obvious enhancement (arrow)

Zhao, SS., Yan, LF., Feng, XL. et al. Incidence and radiological pattern of eosinophilic granuloma: a retrospective study in a Chinese tertiary hospital. J Orthop Surg Res 14, 123 (2019). https://doi.org/10.1186/s13018-019-1158-1](attachment:c9257bea-2af7-4a9c-bb89-bfe20a82dc73:13018_2019_1158_Fig3_HTML.png)

Three-year-old female presenting with multiple tumors of the skull. a In the plain radiography, map like bone destruction (arrow). b Axial post-contrast computed tomography (CT) in bone window showed an aggressive lytic lesion with no peripheral sclerosis (arrow). c T2-weighted high signal is demonstrated in bilateral parietal bone (arrow). d Axial enhanced-contrast T1-weighted MRI showed obvious enhancement (arrow)

![Nine-year-old female presenting with skull mass. a, d Right femur showed round cystic expansion damage surrounded with hyperplasia hardening and the layered periosteal reaction (arrow). b, c The lesion showed osteolytic destruction, T1WI showed slightly mixed lower signal, and STIR showed mixed high signal with high STIR signal in adjacent medullary cavity (arrow). e The image characterized osteolytic bone destruction and edema of surrounding soft tissue (arrow)

Zhao, SS., Yan, LF., Feng, XL. et al. Incidence and radiological pattern of eosinophilic granuloma: a retrospective study in a Chinese tertiary hospital. J Orthop Surg Res 14, 123 (2019). https://doi.org/10.1186/s13018-019-1158-1](attachment:e6545bec-3da6-4489-8fd5-dcb724d466ef:13018_2019_1158_Fig4_HTML.png)

Nine-year-old female presenting with skull mass. a, d Right femur showed round cystic expansion damage surrounded with hyperplasia hardening and the layered periosteal reaction (arrow). b, c The lesion showed osteolytic destruction, T1WI showed slightly mixed lower signal, and STIR showed mixed high signal with high STIR signal in adjacent medullary cavity (arrow). e The image characterized osteolytic bone destruction and edema of surrounding soft tissue (arrow)

![Fourteen-year-old male presenting with left clavicular lesion. a Expansive bone destruction on the left clavicle (arrow). b There was a destructive mass with a prominent soft tissue component (arrow) demonstrated on axial non-contrast computed tomography (CT) in soft tissue window. c, d Axial and coronal CT in bone window showed hyperosteogeny and sclerosis (arrow). e The mass had components that was hyperintense (arrow) to region on axial STIR-weighted magnetic resonance imaging (MRI). f Axial MRI T1 sequence revealed soft tissue mass (arrow)

Zhao, SS., Yan, LF., Feng, XL. et al. Incidence and radiological pattern of eosinophilic granuloma: a retrospective study in a Chinese tertiary hospital. J Orthop Surg Res 14, 123 (2019). https://doi.org/10.1186/s13018-019-1158-1](attachment:eaf5cf41-b295-4bb1-8d71-5d5cb14c3e62:13018_2019_1158_Fig5_HTML.png)

Fourteen-year-old male presenting with left clavicular lesion. a Expansive bone destruction on the left clavicle (arrow). b There was a destructive mass with a prominent soft tissue component (arrow) demonstrated on axial non-contrast computed tomography (CT) in soft tissue window. c, d Axial and coronal CT in bone window showed hyperosteogeny and sclerosis (arrow). e The mass had components that was hyperintense (arrow) to region on axial STIR-weighted magnetic resonance imaging (MRI). f Axial MRI T1 sequence revealed soft tissue mass (arrow)