Diagnostic Radiology/Musculoskeletal Imaging/Tumors Basic/Fibrous dyplasia From Wikibooks, the open-content textbooks collection Fibrous dysplasia is a benign, developmental anomaly of the bone-forming mesenchyme in which the medullary cavity is replaced with fibrous material, woven bone, and spindle cells. Virtually any bone in the body can be affected. It is a nonhereditary disorder of unknown cause. Fibrous dysplasia does not spread or proliferate, and malignant transformation is rare (0.5%).

Mazabraud's syndrome is a rare entity represented by the association of fibrous dysplasia and intramuscular myxomas. Their association was first reported in 1957 by A. Mazabraud, a French physican.[1] Mazabraud's syndrome does not appear to be hereditary and occurs mostly in women. The myxomas tend to develop and congregate around the thighs, buttocks, and shoulder regions. Their neoplastic nature has been questioned over time. Considering their tendency to group close to the affected segments of the bone involved by fibrous dysplasia, they are believed to be a reactive phenomenon due to local mechanical stress factors. Supporting this hypothesis is the fact that, histologically, they appear to be very close to synovial mucoid cysts occurring in stressed articulations.[2] Others hypothesize that they may be extraosseous manifestations of fibrous dysplasia.[3] When compared with isolated myxomas, their tendency to reoccur after removal is very low; however, note the postsurgical recurrence in this patient. As in our patient, the polyostotic form of fibrous dysplasia is predominant. Malignant transformation (eg, osteosarcoma, fibrosarcoma) in Mazabraud's syndrome has been reported, but the incidence remains very low.[2,4] For the myxomas, early surgery is usually advocated,[4] since involvement of neurovascular structures in advanced cases renders excisions more laborious. Appl Radiol 32(1):49-51, 2003

Author: Mark Clayer, MD, MBBS, FRACS, FAOrthA, Head of Musculoskeletal Tumor Service, Department of Orthopaedics and Trauma, Queen Elizabeth Hospital; Senior Visiting Medical Specialist, Royal Adelaide Hospital and Women's and Children's Fibrous dysplasia is a developmental dysplastic disorder of bone in which immature woven bone is formed directly from abnormal fibrous connective tissue. It is characterized by expanding fibroosseous tissue within affected bones and predominantly is a lesion of the growing skeleton. It is termed a dysplasia because of the inability of involved tissue to form mature lamellar bone from the immature, woven precursor. Monostotic fibrous dysplasia affects only one bone, most commonly the ribs, proximal femur, and craniofacial bones. Polyostotic affects many bones, up to 75% of the skeleton. Monostotic fibrous dysplasia is 7-10 times more common than polyostotic fibrous dysplasia. It also can be associated with systemic conditions, including precocious puberty and skin pigmentation (as in McCune-Albright syndrome). Hospital

Author: Mahesh Kumar Neelala Anand, MBBS, DNB, FRCR, Consulting Staff, Department of Radiology, Pennine Acute Hospitals NHS Trust, Royal Oldham Hospital, Manchester, UK Background: 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. Introduction Differentials Radiograph CT Scan MRI Ultrasound Nuclear Medicine Angiography Intervention Pictures Bibliography

Definition Fibrous dysplasia of bone,a disturbance of medullary bone maintenance in which bone undergoing physiologic lysis is replaced by abnormal proliferation of fibrous tissue, resulting in asymmetric distortion and expansion of bone; may be confined to a single bone (monostotic fibrous dysplasia) or involve multiple bones (polyostotic fibrous dysplasia).

Fibrous Dysplasia is a disease that causes growths or lesions in one (monostotic) or more (polyostotic) bones of the human body. These lesions are tumor-like growths that consist of replacement of the medullary bone with fibrous tissue, causing the expansion and fibrous dysplasia bone cysts weakening of the areas of bone involved. Especially when involving the skull or facial bones, the lesions can cause externally visible deformities. The skull is fibrous dysplasia of the skull fibrous dysplasia heel often, but not necessarily, affected, and any other bone(s) can be involved. Many patients have lesions localized in only monostotic fibrous dysplasia treatment one fibrous dysplasia of the face photos treatments for hip /femur fibrous dysplasia bone (70-80%), fibrous dysplasia on hip and femur but others have them in many bones. In many cases, people suffering from Fibrous Dysplasia also have endocrine diseases and skin pigmentation; the three together constitute McCune-Albright Syndrome. Fibrous Dysplasia is very rare, not much is known about it, and there is no known cure. However, it is known that it is caused by a genetic mutation that occurs sometime during fetal development, and is not hereditary.

The name fibrous dysplasia was coined by Lichtenstein in 1938 to describe a disorder of expanding fibro-osseous lesions that had been referred to as fibrous osteodystrophy, osteodystrophia fibrosa and osteitis fibrosa disseminata. Its etiology is unknown; however, the most widely accepted theory is that it is a developmental abnormality of mesenchyme in which osteoblasts fail to undergo normal morphologic differentiation and maturation. The medullary cavity is filled with fibrous tissue in which trabeculae of poorly calcified primitive new bone are developed by osseous metaplasia. Both sexes are equally affected. It begins early in life, often in infancy, but being frequently asymptomatic it usually remains unrecognized until adulthood.

General Discussion Fibrous dysplasia is a term that refers to either a group of chronic conditions featuring cystic bone growth that may arise from abnormal bone development or to a disease of bone marrow (medullary bone) characterized by benign cysts. Fibrous dysplasia is characterized by uneven growth, pain, brittleness, and deformity of the affected bones. This disorder may involve a single bone (monostotic fibrous dysplasia or Jaffe-Lichtenstein disease) or may affect multiple bones (polyostotic fibrous dysplasia). Fibrous dysplasia is usually evident during childhood, and the bone lesions usually stop developing at puberty. These lesions may be painful, deforming and widespread. The bones most often affected are the ribs, skull, facial bones, thigh bone (femur), shin bone (tibia), upper arm (humerous), and pelvis. Occasionally, the bones in the spine (vertebrae) are affected. Some, but not all, affected individuals experience repeated bone fractures. The exact cause of fibrous dysplasia is not known.

Discussion: - results from a defect is somatic mutation in the gene coding for alpha subunit of Gs, the G protein that stimulates cAMP formation; - overproduction of cAMP, causes overexpression of c-fos, which regulates proliferation and differentiation of osteoblasts and osteoclasts; - results in lesions of bone which results in a haphazard mixture of immature fibrous tissue & small fragments of immature trabecular bone; - angular deformities may result from defective mineralization of immature of immature dysplastic bone; - affected bone becomes widened and adjacent cortical bone becomes thin; - occurs typically in adolescence; - prevalence of malignant transformation (chondrosarcoma or osteosarcoma) is about 0.4 %; - sites of involvement: - rib is involved most often but any bone can be involved; - also seen in proximal femur, proximal tibia, mandible; - pathologic frx: - bone becomes deformed by multiple stress frx which may eventually lead to pathologic frx; - painful stress frxs are esp common in femoral neck; - although dysplastic bone heals at nl rate after frx, resulting callus is also dysplastic, and the disease persists; - prognosis: - progression of the disease is often erratic; - monostotic lesions: have good prognosis; - polyostotic lesions: - tend to remain more active or aggressive; - are known to occassionally undergo malignant transformation to osteosarcoma or fibrosarcoma. - Associated Conditions: - Albrights Syndrome - precocious puberty and cafe au lait pigmentation in females; - child w/ monostotic fibrous dysplasia usually has no symptoms; - polyostotic dz, which usually presents earlier, may be unilateral or widespread, affecting long bones, hands, feet, & pelvis; - prevalence of malignant transformation (chondrosarcoma or osteosarcoma) is about 4 %;

Pictorial Essay AJR 2004; 182:1389-1398 Imaging Findings of Fibrous Dysplasia with Histopathologic and Intraoperative Correlation Kimberly A. Fitzpatrick1, Mihra S. Taljanovic1, Donald P. Speer2, Anna R. Graham3, Jon A. Jacobson4, George R. Barnes1 and Tim B. Hunter1 1 Department of Radiology, University of Arizona College of Medicine, 1501 N Campbell Ave., PO Box 245067, Tucson, AZ 85724-5067. 2 Department of Orthopaedic Surgery, University of Arizona College of Medicine, Tucson, AZ. 3 Department of Pathology, University of Arizona College of Medicine, Tucson, AZ. 4 Department of Radiology, University of Michigan, Ann Arbor, MI. Received July 22, 2003; accepted after revision October 28, 2003. Full text and illustrations

Studies on Tissues from Patients with Fibrous Dysplasia of Bone/McCune Albright Syndrome and Other Disorders of Calcified Tissues Summary: This study will investigate how a gene mutation (change in DNA) causes the abnormal bone in fibrous dysplasia-a condition in which areas of normal bone are replaced with a fibrous growth similar to a scar. The bone abnormalities in fibrous dysplasia can occur in a single bone (monostotic fibrous dysplasia), multiple bones (polyostotic fibrous dysplasia), or in McCune Albright syndrome, in which there are associated glandular abnormalities. This study will also examine calcinosis samples that have been surgically removed from patients with juvenile dermatomyositis.

MedscapeMedscape Family Medicine/Primary Care. 2000;2(2) ©2000 I have a patient with the radiologic diagnosis of fibrous dysplasia. Is this entity in the differential diagnosis of Paget's disease? If so, is treatment with pamidronate indicated?

fibrous dysplasia

fibrous dysplasia

ossifying fibroma