Radiography
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.
Findings
Common locations for lesions are the ribs, craniofacial bones, femoral neck, tibia, and pelvis. Radiographic findings in these and other structures are discussed below.13
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.
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, symmetric or asymmetric, 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.
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.
Computed Tomography
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 extendingposteriorly 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.
Findings
CT is not often required for diagnosis. CT 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).14
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.
Degree of Confidence
CT is not optimal for the differentiation of fibrous dysplasia from other lesions that mimic it. CT findings complement plain radiographic findings.
Magnetic Resonance Imaging
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.
Findings
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.
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 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.
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 the FDA Public Health Advisory or Medscape.
Nuclear Imaging
Findings
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.15,16
Degree of Confidence
The technique is not specific for a firm diagnosis based on the imaging characteristics. The specificity is relatively poor.
More on Fibrous Dysplasia |
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 Imaging: Fibrous Dysplasia |
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References
Macdonald-Jankowski D. Fibrous dysplasia: a systematic review. Dentomaxillofac Radiol. May 2009;38(4):196-215. [Medline].
Harris WH, Dudley HR, Barry RJ. The natural history of fibrous dysplasia. An orthopaedic, pathological, and roentgenographic study. J Bone Joint Surg Am. Mar 1962;44-A:207-33.
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. Mar 2004;86-A(3):531-7.
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.
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].
Resnick D, Niwayama G. Diagnosis of Bone and Joint Disorders. 2nd ed. Philadelphia, Pa: WB Saunders;. 1988: 4057-70.
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. Jun 2009;47(4):302-5. [Medline].
Mancini F, Corsi A, De Maio F, Riminucci M, Ippolito E. Scoliosis and spine involvement in fibrous dysplasia of bone. Eur Spine J. Feb 2009;18(2):196-202. [Medline].
Ziadi S, Trimeche M, Mokni M, Sriha B, Khochtali H, Korbi S. [Eighteen cases of craniofacial fibrous dysplasia.]. Rev Stomatol Chir Maxillofac. Jul 15 2009;[Medline].
Rahman AM, Madge SN, Billing K, Anderson PJ, Leibovitch I, Selva D, et al. Craniofacial fibrous dysplasia: clinical characteristics and long-term outcomes. Eye. Jan 30 2009;[Medline].
Valentini V, Cassoni A, Marianetti TM, Terenzi V, Fadda MT, Iannetti G. Craniomaxillofacial fibrous dysplasia: conservative treatment or radical surgery? A retrospective study on 68 patients. Plast Reconstr Surg. Feb 2009;123(2):653-60. [Medline].
Schwartz DT, Alpert M. The malignant transformation of fibrous dysplasia. Am J Med Sci. Jan 1964;247:1-20. [Medline].
Lädermann A, Stern R, Ceroni D, De Coulon G, Taylor S, Kaelin A. Unusual radiologic presentation of monostotic fibrous dysplasia. Orthopedics. Mar 2008;31(3):282. [Medline].
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. Dec 2008;14(4):177-81. [Medline].
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. Jan-Apr 2009;12(1):72-3. [Medline].
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. Dec 2008;33(12):909-11. [Medline].
Daffner RH, Kirks DR, Gehweiler JA Jr, Heaston DK. Computed tomography of fibrous dysplasia. AJR Am J Roentgenol. Nov 1982;139(5):943-8. [Medline].
De Smet A, Travers H, Neff JR. Chondrosarcoma occurring in a patient with polyostotic fibrous dysplasia. Skeletal Radiol. 1981;7:197.
King RM, Payne WS, Olafsson S, Unni KK. Surgical palliation of respiratory insufficiency secondary to massive exuberant polyostotic fibrous dysplasia of the ribs. Ann Thorac Surg. Feb 1985;39(2):185-7.
Further Reading
Related eMedicine topics
Fibrous Dysplasia (from Orthopedic Surgery)
Osteofibrous Dysplasia
Skeletal Dysplasia
Diastrophic Dysplasia
Developmental Dysplasia of the Hip
Clinical studies
Effect of Risedronate on Bone Morbidity in Fibrous Dysplasia of Bone (PROFIDYS)
Screening and Natural History of Patients With Polyostotic Fibrous Dysplasia and McCune-Albright Syndrome
Keywords
fibrous dysplasia, Lichtenstein-Jaffe's disease, Lichtenstein-Jaffe disease, McCune-Albright's disease, McCune-Albright disease, fibrous osteodystrophy, osteodystrophia fibrosa, osteitis fibrosa disseminata, monostotic form, polyostotic form, craniofacial form, cherubism
