 Hello everyone, welcome back to another session on Tentistry and more. So today we have a bone disease which is fibrous dysplasia. Last session we had seen another bone disease that was Paget's disease in which the bone remodeling, the bone resorption and bone formation is affected. In fibrous dysplasia, here the thing is the fibrous tissue develops in place of normal bone. Fibrous dysplasia, dysplasia is abnormal multiplication or abnormal formation of cells or tissue. So fibrous tissue is forming in place of normal bone. So what happens? It is causing weakening of the affected bone or it deforms or it creates a fracture of those affected bones. So let's get into details of fibrous dysplasia. Fibrous dysplasia by definition. It is a skeletal development anomaly of the bone-forming mesonchyme that manifests as a defect in osteoblastic differentiation and maturation. So here the most important factor is osteoblast whereas in Paget's disease we have seen both osteoblast and osteoclastic activity and their role. Here it is mainly on the osteoblastic differentiation and maturation because it is bone-forming in an improper way that is fibrous replacement is happening. So the skeletal developmental anomaly of the bone-forming mesonchyme which manifests as a defect in osteoblastic differentiation and maturation. So what could be the etiology? Could be due to an idiopathic factor, a non-heritatory factor or a mutation of GNS1 gene. So the pathogenesis is GNS1 gene which encodes a G protein which stimulates CAMP that is cyclic AMP production which continues activation of G proteins happening. So over production of this CAMP in affected tissues there will be hyper function of affected endocrine organs. Ultimately there will be increased proliferation of melanocytes and there will be large cufflates spots and also the CAMP affect on differentiation of osteoblast. So this particular gene which codes for G protein and CAMP is production which stimulates CAMP production which in turn activates the G protein then over production of CAMP there will be hyper function of affected endocrine organs and increased proliferation of melanocytes and also there will be effect on differentiation of osteoblast. So osteoblastic differentiation is interrupted so there will be fibrous formation in place of normal bone. So we have various types that is monostotic, polystotic monostotic when it affects a single bone, polystotic it affects more than one bone and McEwen-Albrade syndrome when this fibrous dysplasia is with cufflates spots and endocrine problems as a broad syndrome when fibrous dysplasia is with intramuscular myxoma and the gender prediction is equal that is male and females are equally affected and most commonly seen between 3 to 15 years and in monostotic this is the asymptomatic they will be asymptomatic till 20 years or 30 years but in polystotic it is asymptomatic till around 10 years. So monostotic form the clinical futures are it is the most commonly affected form of fibrous dysplasia that is 70 to 80 percentage of the cases are monostotic that it affects only one bone it could be rib, femur, tibia, craniofacial bones or humerus so any of these bones will be affected only one bone and pain pathological fractures will be there and also there could be a painless swelling of jaw that is the labial or buckle plate will be expanded and there will be protrusions of inferior border of mandible if it affects the maxilla or mandible. One formata is basically less severe in monostotic version and regarding the teeth there will be malalignment there will be tipping there will be displacement of teeth and if it affects the maxilla bone it will affects the maxillary sinus, zygomatic process, floor of the orbit and extend to the base of skull so that is a monostotic form it affects only one bone and if it is in the jaw there will be labial or buckle plate expansion and protrusions of inferior border of mandible and if it is in maxilla it will affect maxilla sinus, zygomatic process, floor of orbit and up to base of skull there will be malalignment, tipping and displacement of teeth. So what if the polystotic form so it is the remaining portion that is 20 to 30 percentage the sides are similar to this one but it affects more than one bones femur, tibia, pelvis, ribs, skull, facial bones, upper extremities, lumbar spine, clavicle and cervical spine so it affects more than one bone that is why it is good polystotic and usually it tend to occur in a unilateral distribution but bilateral distribution also seen and if it is bilateral distribution it will be very asymmetric and pain on limb and spontaneous fractures will be there and bowing of weight bearing bones so there will be bowing of weight bearing bones the longer bones and curvature of femoral neck and shepherd's crook deformity so shepherd's crook the deformity the bending the curvature of bones will be there the shepherd's crook deformity so that is a polystotic form when it affects more than one bone and another two syndromes we have when it is combined with another problems that is macular albraid syndrome which is all bones are affected and there will be pigmented lesions that is cufflates spores those are the pigmented lesions and also endocrine disturbances that is macular albraid syndrome so what are the endocrine disturbances there will be hyperthyroidism there will be hyper parathyroidism and also cushing syndrome will be there so this combination of endocrine disturbances cathletes spores and fibrous dysplasia is known as macular albraid syndrome and another one is masabroad syndrome which is when fibrous dysplasia with intramuscular myxoma and sarcomatous changes that is carcinoma test changes that is masabroad syndrome intramuscular myxoma along with fibrous dysplasia and sarcomatous changes so cufflates spores is seen in mac bone albraid syndrome and also masabroad syndrome so the most common one is monostotic and the next one is polystotic we have one more type of fibrous dysplasia i forgot to mention it here craniofacial form along with monostotic polystotic macular albraid syndrome and masabroad syndrome so craniofacial fibrous dysplasia it's seen in 10 to 25 percentage of monostotic and also 50 percentage of polystotic form so if it is monostotic it is restricted to craniofacial structures or if it is polystotic the craniofacial bonds involved because it involves more than one bone or it also seen as a isolated craniofacial form that is only within craniofacial bones and what are the bonds affected so it is frontal sphenoid maxillary ethmoid bonds are affected and there will be clinical features like hypertelorism cranial asymmetry visceral impairment exothalmos and blindness so that is another type of fibrous dysplasia so that was another type of fibrous dysplasia now let's move on to the lab finding so basically there is no significant change in serum calcium or phosphorus but there is increased alkaline phosphatase and the basal metabolic rate also increased but on a moderate level this alkaline phosphatase increasing we have seen in pages this is also so in histologic features the monostotic and polystotic the monostotic proliferation of fibroblasts in a compact trauma of interlacing collagen fibres and there will be irregular bony trabeculae scattered throughout the lesion and there will not be specific pattern but it's seen as a c-shaped or chinese letter shaped trabeculas are usually co-woven bond so that is a monostotic one there will be irregular bony trabeculae scattered throughout the lesion in polystotic the lesions rich in spindle shaped fibroblast with swirled appearance within the marrow space and islands of cartilaginous tissue within the lesion and affected bones may have cystic lesions lined by multi-nucleated giant cell so that is in polystotic form the multi-nucleated giant cells and islands of cartilaginous tissue within lesion and in craniofacial fibro dysplasia this particular type when it affects the craniofacial bone it is also known as leontiasis osia or lion face syndrome or leontiasis so this particular lion face syndrome not only seen in fibro dysplasia it is also seen in pages disease we are seen in pages disease and it is also seen in hyperthyroidism and renal osteo dystrophy so leontiasis is not actually a disease itself but a symptom of these diseases that is it is a symptom of fibros dysplasia it is a symptom of pages disease or hyperparathyroidism or renal osteo dystrophy so that when it involves facial and cranial bones it looks a lion face giving this name leontiasis osia lion face syndrome or leontiasis well coming to radiographic findings so we have a network of fine bone trabeculae and there will be increased trabeculations that is relations more opaque and there will be mortal appearance and there is a very characteristic very unique appearance that is ground glass or peed orange appearance that is orange peel appearance that is the opaque areas with many many delicate trabeculae so there will be lots of delicate trabeculae these look like a orange peel appearance or a ground glass appearance which is a very characteristic of fibros dysplasia orange peel or ground glass appearance so in differential diagnosis we have ossifying fibroma pages disease osteo sarcoma chirubism hyperparathyroidism so in treatment we can go for a conservative treatment to prevent deformity in polyostatic form we need to go with a multi disciplinary approach and bisphosphonate therapies like pages disease it is done to improve the functions decrease pain and decrease risk of fracture and also various types of surgical corrections so that's all about fibros dysplasia so the takeaway points is catholate spores mycunabrate syndrome mesobrot syndrome orange peel or ground glass appearance uh land phase syndrome so fibros dysplasia as a name suggests it is the replacement of normal form by fibros tissues resulting in fracture or change in form or shapes so that's all about fibros dysplasia i'll come up with a new topic and to understand more in oral pathology thank you