paget 's disease of bone ( pdb ) was first described in 1877 by sir james paget , a british surgeon and originally named the condition osteitis deformans . the disease is characterized by a focal alteration of bone remodelling , which leads to bone with anomalous structure . the disease is more common in men of older adults and mean age of occurrence is 59  14 years . , we are reporting a rare case of paget 's disease of bone occurring in 26 years young adult . a 26-years - old male patient reported to our institution with a complaint of swelling in the right side of the mandible and in the right supraorbital region since 5 years . patient developed a dull aching pain in the right side of lower jaw since few days and subsequently developed numbness in the lower lip of same side . patient had undergone root canal treatment on 26 and 36 four years ago and there was no relevant medical history . extraoral examination revealed facial asymmetry with widening of the inferior border of mandible on the right side as well as a bulge over the right supraorbital region [ figure 1 ] . intraoral examination revealed a swelling extending from midline to ramus of mandible on the right side measuring about 14  7 cm . the swelling was hard in consistency , sessile and non- tender and not fixed to the underlying structures . extra oral swelling at the lower border of the mandible and supraorbital region on the right side radiographic examination reveals enlarged body of the right side of mandible . an ill - defined radiolucency measuring about 7.5  2 cm is seen extending from the condylar rod to the right angle of the mandible . there is also an ill - defined radiolucency of size 2.5  1.5 cm extending from the distal side of 48 to the mesial side of 46 . a multilocular diffuse radiolucency can also be seen at lower border of mandible [ figure 2 ] . opg shows a multilocular diffuse radiolucency on the right side of mandible in relation to 46,47 , 48 the plain computed tomography ( ct ) scan study shows the bilateral involvement of frontal bone with complete obliteration of frontal sinuses and right sphenoid sinuses , partial obliteration of right ethmoid sinus and bilateral maxillary sinuses . few expansile lytic lesions in mandible with break in the outer cortices , largest measuring 2  1.8 cm ( td  ap ) in the region of right lower third molar causing break in the inner cortex and predominantly involving bilateral condylar process and ramus of right mandible [ figure 3 ] . computed tomographic scan showing expansile radiolucent lesion involving the right mandibular bone there was high elevated serum alkaline phosphatase level , that is 825 bodansky units . incisional biopsy was done on the right side of the mandible near external oblique ridge below third molar . bony trabeculae are lined with osteoblasts and there was also evidence of few multinucleated osteoclasts . marrow spaces were filled with fibro - vascular connective tissue with large number of blood vessels filled with rbcs [ figures 4 and 5 ] . photomicrograph showing highly vascular bone marrow ( h&e,400 ) photomicrograph showing bony trabeculae with prominent reversal lines ( h&e,400 ) based on the clinical , radiographic , ct scan , biochemical and histopathological findings , diagnosis of pdb was rendered . pdb is a localized bone disorder that affects widespread areas of the skeleton through increased bone remodelling . the pathologic process is initiated by overactive osteoclastic bone resorption followed by a compensatory increase in osteoblastic new bone formation . there is a high prevalence in western europe with an incidence of 3 - 4% in middle aged people , increasing to 10% in the elderly . pdb is occasionally described in early adult life that is , below 40 years of age . pdb is diagnosed relatively often among the adult population and its prevalence increase with age . s holgado et al . , studied that 5.7% of the patients were diagnosed before 40 years of age . renier and audran suggested that pdb probably starts in youth but is not diagnosed until later . a viral cause has been proposed based upon evidence of a paramyxoviral infection of these cells , but a specific virus has not yet been isolated . but there is also hypoththesis that vitamin d deficiency in children may express later as paget 's disese . it has been known for many years that pdb sometimes occurs in more than one member of a family . pedigree studies led to the suggestions that in some unusual families , susceptibility to the disorder may have an autosomal dominant mode of inheritance . ethel and others suggested that first degree relatives of patients with pdb have increased risk of developing the disorder , especially if the affected relatives have early age at diagnosis or deforming bone disease . the family members sharing a common environment may be more likely than unrelated persons to have common exposure to an infectious agent or to transmit the agent to each other through personal contact . goode suggested that mutations affecting the sqstm1 gene that encodes the p62 protein often found in pdb patients , although environmental factors also play important role in disease etiology . the disease is characterized by abnormal remodelling of the bone and is divided into three phases . initially there is osteolytic phase in which excessive bone resorption occurs due to over - activated osteoclasts , then mixed phase with features of resorption and sclerosis both . the last phase is the burnt out phase or sclerotic phase where new bone formation occurs irregularly and excessively by osteoblasts . polyostotic form is the most common type but , recent trend show that numbers of monostotic cases are increasing up to 40% . suggested that appendicular and monostotic bone involvement was more frequent in the younger age - group although these differences not statistically significant . the complicating features of paget 's disease are bone pain , deformity ; pathological fractures pagetic arthritis , deafness , cranial nerve palsies and spinal stenosis . sarcomatous change affects around 1% of patients , the commonest type is osteosarcoma ( 70 - 80% ) followed by fibrous histiosarcoma ( 20% ) , chondrosarcoma ( 5 - 10% ) and angiosarcoma ( 1% ) . people with pdb are at an increased risk of developing heart failure with figures of 3 - 4% . diagnosis is ultimately made through image and laboratory findings . serum alkaline phosphatase ( ap ) is the most sensitive and widely used biochemical marker of the disease . manero ruiz and others have suggested that in a young adult with high ap values will include pdb in the differential diagnosis . image findings rely on disease progression to be classified in three distinct stages ; lytic phase , with initial resorption characterized by osteolysis , established by osteoclastic activity ; mixed phase , with vascular and osteoblastic repair , leading to thickening and distortion of cortical and trabecular bone ; and the blastic phase , which curses appositional new bone with a sclerosing scarring aspect . histopathology in pdb shows osteolysis which is followed by a compensatory increase in bone formation induced by osteoblasts recruited to the area . the resorbed bone is replaced and the marrow spaces are filled by an excess of fibrous connective tissue with a marked increase in blood vessels , causing the bone to become hypervascular . abnormally enlarged trabeculae reveal mosaic pattern of reversal lines that have formed due to continuous bone deposition accompanied by simultaneous disordered bone resorption . the end stage of the disease shows a typical jigsaw puzzle or mosaic pattern of cemental lines representing randomly oriented bone cemented together . among bisphosphonates , orally administered etidronate , tiludronate , alendronate and risedronate as well as intravenous pamidronate and zoledronic acid have been widely used for the treatment of pdb . alendronate and risedronate are particularly potent oral anti - resorptive drugs for the treatment of pdb , with effects that are comparable with those of intravenous pamidronate and zoledronic acid . the most widely recommended protocols for the treatment of pdb with oral bisphosphonates is 40 mg / day of alendronate for 6 months and 30 mg / day of risedronate for 2 months . the pdb is rarely encountered in younger age - group that is , below 40 years of age ; here we reported a case of pdb in 26 years aged male patient . increased serum ap is the most sensitive and widely used biochemical marker of the disease along with clinical , radiographic findings and histological findings comprising of reversal lines and highly vascular bone marrow , favour the diagnosis of paget 's disease of bone . as many authors have suggested , the disease may have started and gone unnoticed in younger age but gets noticed in the later age group .
paget 's disease of bone ( pdb ) is characterized by a focal alteration of bone remodeling , which leads to bone with anomalous structure and altered mechanical properties associated with pain and complications . 
 it is more common in western europe where as rare in africa and asia . 
 the disease is more common in men of older adults and mean age of occurrence is 59  14 years . 
 but it is rarely encountered in patients younger than 40 years of age .