Fibrous dysplasia of bone

Fibrous dysplasia is characterized by fibrous tissue proliferation with osteogenesis through metaplasia, forming immature woven bone. Another lesion shows lamellar trabecular bone forming alongside fibrous proliferation, with osteoblasts covering the trabecular surface.

Common Symptoms

Nan Kangli; precocious puberty; vaginal bleeding; intellectual decline; exophthalmos

Causes

(1) Etiology. The cause is unknown. (2) Pathogenesis. 1. Gross features: the periosteum is unchanged, the cortex is thinned and sometimes can be cut with a scalpel; the cut surface is pale dense tissue with an elastic gritty feel, mainly due to soft brittle osteoid trabeculae within the fibrous tissue, varying with trabecular number and maturity; this tissue is not vascular, though many vascular sections are seen especially in cancellous bone (iliac wing, ribs, pelvis, metaphysis); cystic spaces, edema or hemorrhagic tissue with bloody fluid are sometimes seen; sometimes, especially in the monostotic type, the whole lytic area contains fluid, easily confused with bone cyst; cartilage islands are sometimes seen, more common in children and the metaphysis. 2. Histopathological features: between fine trabeculae there are bundles of fibrous tissue (fibroblasts), with no osteoblasts lining the trabeculae. Generally the delicate collagen network is rich in fibroblasts, mitoses relatively rare, sometimes arranged in a whorl, sometimes containing multinucleate giant cells, mainly in vascular or hemorrhagic areas (especially vascular cancellous bone such as ribs); some areas show fibrous tumor replacing trabeculae, others myxoid tissue. Osteoid and trabeculae are generally sparse and rarely coarse, without osteoblast lining; the trabeculae of fibrous dysplasia are generally woven and cannot form lamellar bone. Vessels are rare, though cystic areas show capillaries and bloody exudate. Sometimes cartilage areas are seen within dysplastic fibro-osseous tissue, as small localized nodules of normal hyaline cartilage; these differ from solitary or multiple enchondromas and resemble the proliferating cartilage of the growing epiphyseal plate or reparative callus; the histological discontinuity between cartilage areas and dysplastic tissue led the author to reject the idea that cartilage results from metaplasia; in most cases arising in the pediatric or adolescent metaphysis, cartilage seems to originate from the epiphyseal plate, while in others subperiosteal cartilage may result from reparative osteocartilaginous callus after recent pathologic fracture, minor fracture or surgery. Histological appearance, like imaging and gross appearance, changes with patient age.

Treatment

Medication, supportive treatment, rehabilitation therapy

Prevention

There are currently no effective preventive measures; early detection and diagnosis are the key.

Recommended Department

It is recommended to visit the oncologic surgery department; before the visit you may first book an appointment and connect with experts through this platform.

Warm reminder: The above information is provided for health education reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek care at a regular hospital in time.