Monostotic fibrous dysplasia is a form of

fibrous dysplasia Fibrous dysplasia is a very rare nonhereditary genetic disorder where normal bone and marrow is replaced with fibrous tissue, resulting in formation of bone that is weak and prone to expansion. As a result, most complications result from fract ...

where only one bone is involved. It comprises a majority of the cases of fibrous dysplasia (approximately 70–80%). It is a rare

bone disease Bone disease refers to the medical conditions which affect the bone. Terminology A bone disease is also called an "osteopathy", but because the term osteopathy is often used to refer to an alternative health-care philosophy, use of the term can ...

characterized by the replacement of normal elements of the bone by

fibrous connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesode ...

, which can cause very painful swellings and bone deformities, and make bone abnormally fragile and prone to fracture. A

congenital A birth defect is an abnormal condition that is present at childbirth, birth, regardless of its cause. Birth defects may result in disability, disabilities that may be physical disability, physical, intellectual disability, intellectual, or dev ...

, noninherited, benign anomaly of bone development in a single bone, it consists of the replacement of normal marrow and cancellous

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

by immature bone with fibrous stroma. Monostotic fibrous dysplasia occurs with equal frequency in both sexes and normally develops early in life, with lesions frequently identified late in the first and early second decades. Most patients are asymptomatic, with the diagnosis often established after an incidental finding or with pain, swelling, or fracture. Lesions usually enlarge in proportion to skeletal growth and the abnormal replacement remain active only until skeletal maturity. Monostotic fibrous dysplasia does not convert into the polyostotic type. When symptoms are present, they often are nonspecific, including pain, swelling, or pathologic fracture. It most often affects the

ribs The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great vessels ...

(28%), proximal

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

(23%),

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

, cranio

facial bone The facial skeleton comprises the ''facial bones'' that may attach to build a portion of the skull. The remainder of the skull is the neurocranium. In human anatomy and development, the facial skeleton is sometimes called the ''membranous viscer ...

s (10-25%) and

humerus The humerus (; : humeri) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius (bone), radius and ulna, and consists of three sections. The humeral upper extrem ...

(10-25%).

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Osteopathies Genetic disorders with no OMIM {{musculoskeletal-disease-stub

See also

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