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Fibrous Dysplasia Imaging

  • Author: Mahesh Kumar Neelala Anand, MBBS, DNB, FRCR; Chief Editor: Felix S Chew, MD, MBA, MEd  more...
 
Updated: Nov 18, 2015
 

Overview

Fibrous dysplasia is a skeletal developmental anomaly of the bone-forming mesenchyme that manifests as a defect in osteoblastic differentiation and maturation. Virtually any bone in the body can be affected. It is a nonhereditary disorder of unknown cause. (See the images below.)[1, 2, 3, 4, 5, 6, 7]

Image shows homogeneous loss of the normal trabecu Image shows homogeneous loss of the normal trabecular pattern in the shaft of the humerus, with a ground-glass appearance caused by fibrous dysplasia.
Axial bone-window CT scan shows a bony mass that e Axial bone-window CT scan shows a bony mass that expands the ethmoidal sinuses; this finding is consistent with fibrous dysplasia. Note the relative homogeneous attenuation of the lesion.
T1-weighted axial MR scan showing low signal withi T1-weighted axial MR scan showing low signal within the shaft of right femur in a patient with fibrous dysplasia.

Preferred examination

Plain radiography is the first-line study. Usually, the diagnosis is straightforward when typical features are present. Computed tomography (CT) scanning may be required to assess complex regions such as the spine, pelvis, chest, and facial skeleton.[8, 9, 10, 11] Bone scintigraphy has a limited role in the detection of subtle pathologic fractures. In fibrous dysplasia, the features on a bone scan are nonspecific for diagnostic purposes. Magnetic resonance imaging (MRI) may be necessary to assess cord compression when the spine is involved.[12, 13, 14]

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Radiography

Common locations for lesions are the ribs, craniofacial bones, femoral neck, tibia, and pelvis. Radiographic findings in these and other structures are discussed below.[15]

Long and short tubular bones

The usual appearance of fibrous dysplasia includes a lucent lesion in the diaphysis or metaphysis, with endosteal scalloping and with or without bone expansion and the absence of periosteal reaction. Usually, the matrix of the lucency is smooth and relatively homogeneous; classically, this finding is described as a ground-glass appearance. Irregular areas of sclerosis may be present with or without calcification. The lucent lesion has a thick sclerotic border and is called the rind sign. (See the image below.)

Image shows homogeneous loss of the normal trabecu Image shows homogeneous loss of the normal trabecular pattern in the shaft of the humerus, with a ground-glass appearance caused by fibrous dysplasia.

The lesion may extend into the epiphysis only after fusion. Premature fusion of the ossification centers may occur, resulting in adult dwarfism. The dysplastic bone may undergo calcification and enchondral bone formation.

Skull and facial bones

The frontal bone is involved more frequently than the sphenoid, with obliteration of the sphenoid and frontal sinuses. The skull base may be sclerotic. Single or multiple, symmetrical or asymmetrical, radiolucent or sclerotic lesions in the skull or facial bones may be present. The external occipital protuberance may be prominent; however, these features are less common in Paget disease, neurofibromatosis, and meningioma.

Most commonly, maxillary and mandibular involvement has a mixed radiolucent and radiopaque pattern, with displacement of the teeth and distortion of the nasal cavities. The diploic space is widened, with displacement of the outer table. The inner table of the skull is spared in fibrous dysplasia, unlike in Paget disease. Cystic calvarial lucencies, which commonly cross the sutures with sclerotic margins, may have a doughnut configuration.

Pelvis and ribs

These bones have lucencies, with a diffuse ground-glass appearance and rind lesions. Cystic lesions are common. Protrusio acetabuli is a feature on the pelvic radiograph. (See the image below.)

Chest radiograph shows expansion of multiple ribs Chest radiograph shows expansion of multiple ribs involved by fibrous dysplasia that mimics pleural masses.

Spine

Spinal involvement is common in polyostotic disease and rare in monostotic disease. Well-defined, expansile, radiolucent lesions with multiple internal septa or striations involve the vertebral body and, occasionally, the pedicles and arches. Paraspinal soft-tissue extension and vertebral collapse are rare. Kyphotic deformity and spinal cord compression may occur.

Degree of confidence

Plain radiographs are highly specific when characteristic features are present in a lesion. However, the specificity decreases when the lesion occurs at more complex sites, such as the spine, the skull, and, sometimes, the pelvis. The identification of malignant change and soft-tissue extension on plain radiographs may be difficult; cross-sectional imaging may be required.

Radiographic features suggestive of malignant degeneration include a rapid increase in the size of the lesion and a change from a previously mineralized bony lesion to a lytic lesion.

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Computed Tomography

CT scanning is not often required for diagnosis. The modality demonstrates the nature of the lesion better by characterizing the matrix of the lesion. It also depicts expansion of the affected bone and its subtle mineral contents. It can demonstrate subtle nondisplaced pathologic fractures. CT is extremely useful in evaluating the extent of disease in complex locations, such as the facial bones, pelvis, chest wall, and spine. Usually, attenuation is in the range of 70-130 HU (Hounsfield unit).[8, 9, 10, 11]

In the skull, the outer table always expands outward. Therefore, the lesion is invariably convex; both tables are intact, although they are thinner. In the spine, CT can demonstrate the extent of bony disease and compromise of the spinal canal space. Paraspinal soft-tissue extension can be demonstrated at CT. CT scans may suggest malignant transformation, with the definition of an extraosseous soft-tissue mass and bone destruction. (See the images below.)

Axial bone-window CT scan shows a bony mass that e Axial bone-window CT scan shows a bony mass that expands the ethmoidal sinuses; this finding is consistent with fibrous dysplasia. Note the relative homogeneous attenuation of the lesion.
Image shows focal areas of calcification in cranio Image shows focal areas of calcification in craniofacial fibrous dysplasia.
Coronal image shows craniofacial fibrous dysplasia Coronal image shows craniofacial fibrous dysplasia extending posteriorly into the sphenoidal sinus.
Coronal CT scan shows craniofacial fibrous dysplas Coronal CT scan shows craniofacial fibrous dysplasia with expansion of paranasal sinuses caused by a homogeneous mass. The inferior part of the vestibule of the nasal cavity has a soft-tissue component.

Degree of confidence

CT scanning is not optimal for the differentiation of fibrous dysplasia from other lesions that mimic it. CT findings complement plain radiographic findings.

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Magnetic Resonance Imaging

On T1-weighted MRIs, the lesion has low-to-intermediate signal intensity equal to that of muscle. T2-weighted images also show low signal intensity owing to the high content of collagen and bone. Cartilaginous islands may be present in some lesions, and they appear as areas of high signal intensity on T2-weighted images. In children, T2-weighted images show hyperintense signal greater than that of subcutaneous fat; this finding is characteristic of fibrous dysplasia. (See the images below.)[10]

An area of low signal on T1-weighted MR scan, with An area of low signal on T1-weighted MR scan, within the proximal shaft of the right femur. Note the narrow zone of transition from lesion to normal marrow.
T1-weighted axial MR scan showing low signal withi T1-weighted axial MR scan showing low signal within the shaft of right femur in a patient with fibrous dysplasia.
T2-weighted axial image showing a heterogeneous hi T2-weighted axial image showing a heterogeneous high signal within a fibrous dysplasia in the proximal shaft of the right femur.
Sagittal T2-weighted image of fibrous dysplasia le Sagittal T2-weighted image of fibrous dysplasia lesion in the shaft of the femur. Note there is some degree of expansion of the bone.

Also, fluid-fluid levels are reported in fibrous dysplasia. On short–inversion time inversion-recovery (STIR) images, the signal intensity of the lesion may be very high. MRI may be useful in assessing malignant change and demonstrating extension of the tumor into the surrounding soft tissues.

For postoperative follow-up, gadolinium-enhanced MRI is useful in demonstrating the proliferation of fibrocellular tissue.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Systemic Fibrosis. 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.

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 the whites 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 Medscape.

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Nuclear Imaging

In fibrous dysplasia, accumulation of isotope increases because of the lesion's hypervascularity. Hot spots or increased uptake of the radioisotope tracer technetium-99m methylene diphosphonate (99m Tc MDP) occurs in the spine, pelvis, ribs, and appendicular skeleton. Pathologic or stress fractures also can increase isotopic activity in the lesions. The features on the bone scan are nonspecific for a conclusive diagnosis based solely on the distribution of the isotope.[12, 13]

Degree of confidence

The technique is not specific for a firm diagnosis based on the imaging characteristics. The specificity is relatively poor.

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Contributor Information and Disclosures
Author

Mahesh Kumar Neelala Anand, MBBS, DNB, FRCR Consultant Interventional Radiologist, Department of Radiology, Matrix Medical Imaging Limited, UK; Consultant Interventional Radiologist, Mediclinic Hospitals, UAE

Mahesh Kumar Neelala Anand, MBBS, DNB, FRCR is a member of the following medical societies: Cardiovascular and Interventional Radiological Society of Europe, European Society of Gastrointestinal and Abdominal Radiology, British Society of Interventional Radiology, Indian Radiological and Imaging Association, British Society of Gastroenterology, Radiological Society of North America, Royal College of Radiologists

Disclosure: Nothing to disclose.

Specialty Editor Board

Bernard D Coombs, MB, ChB, PhD Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand

Disclosure: Nothing to disclose.

Murali Sundaram, MBBS FRCR, FACR, Professor of Radiology and Consulting Staff, Cleveland Clinic Lerner College of Medicine of CWRU

Murali Sundaram, MBBS is a member of the following medical societies: American College of Radiology, American Medical Association, American Roentgen Ray Society, Association of University Radiologists, International Skeletal Society, Radiological Society of North America, Society of Skeletal Radiology

Disclosure: Nothing to disclose.

Chief Editor

Felix S Chew, MD, MBA, MEd Professor, Department of Radiology, Vice Chairman for Academic Innovation, Section Head of Musculoskeletal Radiology, University of Washington School of Medicine

Felix S Chew, MD, MBA, MEd is a member of the following medical societies: American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America

Disclosure: Nothing to disclose.

Additional Contributors

Michael A Bruno, MD, MS, FACR Professor of Radiology and Medicine, Pennsylvania State University College of Medicine; Director, Radiology Quality Management Services, The Penn State Milton S Hershey Medical Center

Michael A Bruno, MD, MS, FACR is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America, Society of Nuclear Medicine and Molecular Imaging, Society of Skeletal Radiology

Disclosure: Received royalty from Oxford Press for book author/editor & reviewer; Received royalty from Elsevier Press for book author / editor.

References
  1. Macdonald-Jankowski D. Fibrous dysplasia: a systematic review. Dentomaxillofac Radiol. 2009 May. 38(4):196-215. [Medline].

  2. Harris WH, Dudley HR, Barry RJ. The natural history of fibrous dysplasia. An orthopaedic, pathological, and roentgenographic study. J Bone Joint Surg Am. 1962 Mar. 44-A:207-33.

  3. Leet AI, Magur E, Lee JS, et al. Fibrous dysplasia in the spine: prevalence of lesions and association with scoliosis. J Bone Joint Surg Am. 2004 Mar. 86-A(3):531-7.

  4. Lichenstein L, Jaffe HL. Fibrous dysplasia of bone: a condition affecting one, several or many bones, the graver cases of which may present abnormal pigmentation of skin, premature sexual development, hyperthyroidism or still other extraskeletal abnormalities. Arch Pathol. 1942. 33:777.

  5. National Institutes of Health. Osteoporosis and Related Bone Disorders-National Resource Center Web site. Fast Facts on Fibrous Dysplasia page. Available at: http://www.osteo.org/default.asp. Washington, DC: National Institutes of Health. 2001. [Full Text].

  6. Kruse A, Pieles U, Riener MO, Zunker Ch, Bredell MG, Grätz KW. Craniomaxillofacial fibrous dysplasia: a 10-year database 1996-2006. Br J Oral Maxillofac Surg. 2009 Jun. 47(4):302-5. [Medline].

  7. Mancini F, Corsi A, De Maio F, Riminucci M, Ippolito E. Scoliosis and spine involvement in fibrous dysplasia of bone. Eur Spine J. 2009 Feb. 18(2):196-202. [Medline].

  8. Bulakbasi N, Bozlar U, Karademir I, Kocaoglu M, Somuncu I. CT and MRI in the evaluation of craniospinal involvement with polyostotic fibrous dysplasia in McCune-Albright syndrome. Diagn Interv Radiol. 2008 Dec. 14(4):177-81. [Medline].

  9. Unal Erzurumlu Z, Celenk P, Bulut E, Barıs YS. CT Imaging of Craniofacial Fibrous Dysplasia. Case Rep Dent. 2015. 2015:134123. [Medline].

  10. Atalar MH, Salk I, Savas R, Uysal IO, Egilmez H. CT and MR Imaging in a Large Series of Patients with Craniofacial Fibrous Dysplasia. Pol J Radiol. 2015. 80:232-40. [Medline].

  11. An G, Gui L, Liu J, Niu F, Chen Y, Wang M. Treatment of fibrous dysplasia orbital deformities with digital imaging guidance. J Craniofac Surg. 2015 Mar. 26 (2):449-51. [Medline].

  12. Sood A, Raman R, Jhobta A, Dhiman DS, Seam RK. Normal technetium-99m-MDP uptake in fibrous dysplasia of the hip. Hell J Nucl Med. 2009 Jan-Apr. 12(1):72-3. [Medline].

  13. Bonekamp D, Jacene H, Bartelt D, Aygun N. Conversion of FDG PET activity of fibrous dysplasia of the skull late in life mimicking metastatic disease. Clin Nucl Med. 2008 Dec. 33(12):909-11. [Medline].

  14. Qu N, Yao W, Cui X, Zhang H. Malignant transformation in monostotic fibrous dysplasia: clinical features, imaging features, outcomes in 10 patients, and review. Medicine (Baltimore). 2015 Jan. 94 (3):e369. [Medline].

  15. Lädermann A, Stern R, Ceroni D, De Coulon G, Taylor S, Kaelin A. Unusual radiologic presentation of monostotic fibrous dysplasia. Orthopedics. 2008 Mar. 31(3):282. [Medline].

  16. Resnick D, Niwayama G. Diagnosis of Bone and Joint Disorders. 2nd ed. Philadelphia, Pa: WB Saunders;. 1988: 4057-70.

 
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Image shows homogeneous loss of the normal trabecular pattern in the shaft of the humerus, with a ground-glass appearance caused by fibrous dysplasia.
Chest radiograph shows expansion of multiple ribs involved by fibrous dysplasia that mimics pleural masses.
Axial bone-window CT scan shows a bony mass that expands the ethmoidal sinuses; this finding is consistent with fibrous dysplasia. Note the relative homogeneous attenuation of the lesion.
Image shows focal areas of calcification in craniofacial fibrous dysplasia.
Coronal image shows craniofacial fibrous dysplasia extending posteriorly into the sphenoidal sinus.
Coronal CT scan shows craniofacial fibrous dysplasia with expansion of paranasal sinuses caused by a homogeneous mass. The inferior part of the vestibule of the nasal cavity has a soft-tissue component.
An area of low signal on T1-weighted MR scan, within the proximal shaft of the right femur. Note the narrow zone of transition from lesion to normal marrow.
T1-weighted axial MR scan showing low signal within the shaft of right femur in a patient with fibrous dysplasia.
T2-weighted axial image showing a heterogeneous high signal within a fibrous dysplasia in the proximal shaft of the right femur.
Sagittal T2-weighted image of fibrous dysplasia lesion in the shaft of the femur. Note there is some degree of expansion of the bone.
 
 
 
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