Follow up A CT of the Chest showed no evidence of pulmonary metastases. The patient underwent resection of the right proximal tibia and fibula followed by placement of a knee prosthesis. Dysplasia Fibrous dysplasia is a congenital, non-hereditary skeletal disorder that occurs with equal frequency in males and females. It is a developmental anomaly of bone formation in which the marrow is replaced by fibrous tissue. One percent of biopsied bone lesions are due to fibrous dysplasia.
Monostotic disease is more common than polyostotic disease.
When polyostotic, all the lesions tend to occur on one side of the body. The constellation of polyostotic fibrous dysplasia, skin pigmentation and precocious puberty has the eponym McCune Albright Syndrome. The conversion of the fibrous tissue to bone is thought to result from fibro-osseous metaplasia. Few mature osteoblasts and osteoclasts are seen. Recently, gene mutations have been delineated that cause inappropriate proliferation and differentiation of osteoblasts resulting in the production of the fibrotic bone matrix seen in both monostotic and polyostotic fibrous dysplasia.