eMedicine Specialties > Radiology > Musculoskeletal
Eosinophilic Granuloma, Skeletal: Imaging
Updated: May 14, 2008
Radiography
Findings
Chest radiograph in a 30-year-old woman who presented with shortness of breath and a palpable swelling over the right parietal region. The radiograph shows an interstitial lung pattern with a honeycomb appearance in the upper zones (see also Image 2 in Multimedia).
Lateral skull radiograph in a 30-year-old woman with shortness of breath and a palpable swelling over the right parietal region (same patient as in Image 1 in Multimedia) shows 2 purely lytic lesions in the frontoparietal region of the skull. The larger parietal lesion has beveled edges, suggestive of an eosinophilic granuloma. Biopsy results confirmed the diagnosis of eosinophilic granuloma.
Plain radiograph of the pelvis in a 10-year-old girl shows a lytic lesion of eosinophilic granuloma within the left ileum. Biopsy results confirmed the diagnosis of eosinophilic granuloma.
Chest radiograph in a 9-year-old boy who presented with mid dorsal pain. Note the collapsed vertebra and paraspinal soft tissue mass.
Anteroposterior radiograph of the dorsal spine in a 9-year-old boy with mid dorsal pain (same patient as in Image 9 in Multimedia). These results confirm the chest radiographic findings.
- In descending order of frequency, sites involved with monostotic osseous disease include the calvarium, mandible, ribs, long bones of the upper extremity, pelvis, and vertebrae (see Images above and Images 1-2, 6-10 in Multimedia).
- When tubular bones are involved, diaphyseal and metaphyseal localization is more frequent than epiphyseal localization. Epiphyseal lesions may cross the open physeal plate.
- The skull is affected in one half of patients.3,6
- 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.
- Sclerosis may occur around orbital lesions.
- Marginal sclerosis may occur during the healing phase in up to 50% of patients with a calvarial lesion.
- A hole-within-a-hole appearance may occur as a result of uneven erosion of the inner and outer tables of the skull.
- A soft tissue mass overlying the skull defect may be obvious and, often, clinically palpable.
- A soft tissue mass is occasionally seen with orbital lesions, with or without underlying bone erosion.
- A button sequestrum is seen because a central bone opacity within a lytic lesion is an unusual presentation.
- Mandibular lesions may be associated with gingival and soft tissue swelling and floating teeth (see Image below and Image 6 in Multimedia).
Anteroposterior radiograph of the mandible (left image) in a 10-year-old boy who presented with swelling of the left mandible. A lytic expanding lesion is seen within the ramus of the left mandible. An oblique view of the mandible (right image) shows floating teeth within the lytic bone lesion) (see also Image 7 in Multimedia).
- The 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 may be associated with cortical thinning, intracortical tunneling, and erosion of the cortex, as well as an adjacent soft tissue mass.
- Laminated periosteal new bone formation is common around the involved segment of bone.
- Spread across growth plates is unusual.
- Tubular long bone lesions may appear rapidly over 3 weeks.
- The scapulae and pelvis show destructive lesions.
- Periosteal elevation is minimal, and some lesions show sclerotic margins, particularly lesions occurring in the supra-acetabular regions.
- 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.8,10,11
- Vertebra plana is more common in the dorsal spine.
- Associated kyphosis has not been described, but scoliosis can occur.
- EG can produce expansile lytic lesions of the vertebral bodies and the posterior vertebral elements.
- An associated paraspinal mass may occasionally occur.
- Involvement of the second cervical vertebra is extremely rare; it may cause atlantoaxial instability.14
- Lung involvement is seen in as many as 20% of patients, with an incidence of 0.05-0.5 per 100,000 patients annually.
- Lung lesions are seen in an older subset of patients, ie, those aged 20-40 years.
- Plain radiographic findings may demonstrate an alveolar pattern in an early stage, which may be followed by nodular shadows (3-10 mm) and/or a reticulonodular pattern with a predilection for the apices.
- Eventually, fibrosis and a honeycomb lung may ensue.
- Recurrent pneumothoraces occur in 20% of patients.
- Hilar lymphadenopathy and pleural effusions are rare.
Degree of Confidence
Plain radiography remains the mainstay of diagnosis in patients with EG, although a specific diagnosis cannot always be made without bone biopsy because children and adolescents are not spared skeletal neoplasms.
False Positives/Negatives
A wide variety of bone lesions may mimic EG, including infections, traumatic lesions, and neoplasms (see Differentials). A false-negative diagnosis of EG made by using plain radiographs is exceptional, although difficulty may be encountered with lesions in areas with more complex anatomy, such as the posterior elements of the vertebral bodies; in these cases, conventional tomography or CT may useful.
Computed Tomography
Findings
Transaxial nonenhanced CT scans of the skull in a 28-year-old woman who presented with a palpable swelling over the calvarium. Scanogram of the patient's skull shows a geographic lytic lesion within the parieto-occipital region. Transaxial scan through the vertex, examined in a bone window, shows an expanding lytic lesion within the diploic space (see also Images 4-5 in Multimedia).
Transaxial nonenhanced CT scans through the vertex in a 28-year-old woman with a palpable swelling over the calvarium (same patient as in Image 3 in Multimedia), examined in a brain window. Images show destruction of both the outer and inner tables of skull; however, no brain involvement is noted.
CT scans may be particularly useful in osseous lesions in areas with complex anatomy, such as the mastoids, atlantoaxial joints, and posterior elements of the vertebral bodies. Also, soft tissue components are better depicted with CT than with other imaging modalities. The destruction of the mastoid, petrous ridge, tegmen tympani, and lateral sinus plate and the destruction of the inner and external ear are depicted elegantly on CT scans (see Images above and Images 3-4 in Multimedia). CT may demonstrate an isoattenuating and homogeneously enhancing mass in the hypothalamus/pituitary gland.
Degree of Confidence
CT is considerably better than plain radiography and conventional tomography in depicting an intracranial extension of EG.
False Positives/Negatives
CT appearances of EG are nonspecific, and a variety of inflammatory and neoplastic processes may mimic EG.
Magnetic Resonance Imaging
Findings
T1-weighted nonenhanced sagittal MRI through the spine in a 9-year-old boy with mid dorsal pain (same patient as in Images 9-10 in Multimedia) shows the vertebra plana. Note the preserved disk spaces. Biopsy results confirmed the diagnosis of eosinophilic granuloma.
On spin-echo MRIs, osseous lesions of EG reveal decreased signal intensity on T1-weighted images and high signal intensity on T2-weighted sequences. The lesion may enhance after the administration of a gadolinium-based contrast agent (see Image above and Image 11 in Multimedia).
Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have recently been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Fibrosing Dermopathy. The disease has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans.
As of late December 2006, the FDA had received reports of 90 such cases of NSF/NFD. Worldwide, over 200 cases have been reported, according to the FDA. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on thewhites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see the FDA Public Health Advisory or Medscape.
Degree of Confidence
The value of using MRI for patients with EG lies in the sensitivity of MRI; its specificity is low. However, the cost of the procedure and the procedural problems encountered in imaging young children confer no advantages over plain radiography.
False Positives/Negatives
The soft tissue component around the osseous lesion has poor definition and shows signal inhomogeneity; the appearance may mimic that of a malignant tumor, infection, or stress fracture.
Nuclear Imaging
Findings
Radionuclide bone scans in a 28-year-old woman with a palpable swelling over the calvarium (same patient as in Images 3-4 in Multimedia) show a solitary lesion within the skull and a photon-deficient mass surrounded by a rim of intense activity. Biopsy results confirmed the diagnosis of eosinophilic granuloma.
EG shows a variety of activity patterns on radionuclide bone scintigrams obtained by using technetium-99m (99m Tc) diphosphonate. The bone lesions may be hot, cold, or cold with an area of increased surrounding reparative-ring activity. Areas of increased activity vary in intensity. In the lower limbs, EG lesions tend to appear more elongated and diffuse than bone metastasis. Recurrences are identified more readily with fewer false-negative findings (see Image above and Image 5 in Multimedia).
Bone lesions in all types of Langerhans cell histiocytosis are not gallium-67 (67 Ga) citrate–avid, but67 Ga imaging may be helpful for detection of nonosseous lesions. Hence, it is useful in the initial assessment and serial follow-up imaging of patients with Langerhans cell histiocytosis. Thallous chloride-201 uptake detected on single-photon emission CT (SPECT) scans has been reported in a patient with skull EG, which was photon deficient on an 99m Tc methylene diphosphonate uptake study.12
Degree of Confidence
Radiographic examination and radionuclide bone imaging are complementary techniques in detecting bone lesions in bone marrow disorders, including EG. Scintigraphy is more useful in cases of unifocal EG than in cases of multifocal disease, in which radiography is superior.
False Positives/Negatives
Negative radionuclide findings occur in 35% of patients with known EG in whom plain radiographic findings are positive.
Angiography
Findings
External carotid angiogram in a 10-year-old boy with swelling of the left mandible (same patient as in Image 6 in Multimedia) shows an avascular mass within the mandible with stretching of the vessels around the lytic lesion. Biopsy results confirmed the diagnosis of eosinophilic granuloma.
EG shows no neovascularity, and angiography is usually not performed. Rarely, angiography may be performed in patients in whom staging is required before surgical intervention and to exclude other vascular lesions that can mimic EG, such as hemangioma and aneurysmal bone cyst.
Degree of Confidence
In most instances, angiography has little or no role in the investigation of EG.
False Positives/Negatives
Most lesions included in the differential diagnosis of EG are avascular; therefore, differentiation on the basis of angiographic results is usually not possible.
More on Eosinophilic Granuloma, Skeletal |
| Overview: Eosinophilic Granuloma, Skeletal |
 Imaging: Eosinophilic Granuloma, Skeletal |
| Follow-up: Eosinophilic Granuloma, Skeletal |
| Multimedia: Eosinophilic Granuloma, Skeletal |
| References |
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References
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Fenoy AJ, Greenlee JD, Menezes AH, Donovan KA, Sato Y, Hitchon PW, et al. Primary bone tumors of the spine in children. J Neurosurg. Oct 2006;105(4 Suppl):252-60. [Medline].
Flores LG 2nd, Hoshi H, Nagamachi S, et al. Thallium-201 uptake in eosinophilic granuloma of the frontal bone: comparison with technetium-99m-MDP imaging. J Nucl Med. Jan 1995;36(1):107-10. [Medline].
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Osenbach RK, Youngblood LA, Menezes AH. Atlanto-axial instability secondary to solitary eosinophilic granuloma of C2 in a 12-year-old girl. J Spinal Disord. Dec 1990;3(4):408-12. [Medline].
Further Reading
Keywords
EG, Langerhans cell histiocytosis, histiocytosis X, Letterer-Siwe disease, Hand-Schüller-Christian disease, skeletal eosinophilic granuloma, unifocal Langerhans cell histiocytosis, solitary skeletal lesions, bone lesions, multiple skeletal lesions, skeletal lesions, solitary bone lesions, multiple bone lesions
