Teaching Case

A 48 years-old male patient referred to the hospital with longstanding headache which was apparent for the last one year. Bilateral eye movements to superior and lateral were restricted. He was also defining buttock pain bilaterally. Laboratory tests were normal except markedly increased level of serum ALP.

A 48 years-old male patient referred to the hospital with longstanding headache which was apparent for the last one year. Bilateral eye movements to superior and lateral were restricted. He was also defining buttock pain bilaterally. Laboratory tests were normal except markedly increased level of serum ALP. Then x- ray films of the cranium and pelvis, cranial computed tomography(CT) and an MRI study of the cranium with 1.5 T MR scanner, in three planes with SE T1, FSE PD,T2 sequences were performed. The plain radiograms demonstrated marked thickening of the calvarium with the widening of diploe space. Both inner and outer tables were thickened but it was evident on the former. Diffuse sclerosis of the calvarial bones with “cotton wool” appearance was seen. Also the pelvis demonstrated sclerosis with a coarse trabecular pattern. The MR pictures revealed widening of the diploic space with mixed signal intensity on all sequences. Paranasal sinuses and mastoid air cells were obliterated due to the disease affecting the calvarial bones.

Paget’s disease is a chronic disorder of the skeletal system. Its origin is not definitely known. However the current thinking is that a slow virus may be the initiating factor. The disease affects 3-4% of the population over the age of 40 but ıt is more frequently found in the elderly. The men are affected slightly more than women. Paget’s disease may be monostotic or polyostotic. Monostotic disease is not common(10-20%). Pelvis, sacrum, lumbar spine, thoracic spine, femur and calvarium are the most frequently affected bones. The disease progresses through three phases. First the initial phaseof increased osteoclastic activity results in bone resorption. This early phase is osteolytic and is not commonly seen radiologically. It may persist in the skull, as osteoporosis circumscripta. In the mixed phase, increased resorption of bone is followed by increased formation of abnormally coarsened trabeculae of increased volume(mosaic pattern).In the last phase named as sclerotic phase osteoclastic activity declines and osteoblastic activity proceeds. Disorganized new bone of increased density replaces lytic areas. Eventually the disease becomes quiescent.In the long bones the disease begins at a bone end, and as it extends to the other bone end, it is demarcated from normal bone by a “V” shaped zone of transition. Cortical width of long bones increase and bowing deformity may be formed. In the pelvis thickening of trabeculae and iliopectineal line is seen. Picture frame vertebra( condensed, thickened end plates and vertebral margins enclosing a cystic spongiosa) also named as “bone within bone” is the typical appearance observed in the spine. When skull is affected both the inner and outer tables are thickened and the diploic space is widened. In the initial phase, radiolucent osteoporosis circumscripta may be seen. Cotton wool appearnce is evident in the mixed phase. Sclerosis of the skull base may form. Paget’s disease is usually diagnosed as an accidental finding. Initial symptoms usually consist of generalized pain in bones. The neurologic complications result from pagetic involvement of the skull. Expansion of diseased bone can result in compression of cranial nerves as they exit their bony foramina( hearing loss, blindness, facial palsy). Softening of the skull leads to basilar invagination with compression of the brain stem, cerebellum, and lower cranial nerves. Brain stem compression can cause hydrocephalus. Laboratory findings of the disease includes; increased levels os serum ALP and urine hydroxyproline with the normal levels of calcium and phosphorus. Bone scans of the disease demonstrates increased uptake but sclerotic lesions may also show normal uptake. CT and MRI findings are the same with x ray with the advantage of more anatomic detail. On MRI hyperintense areas seen in the diploic space are consistent with fatty marrow displacement whereas the hypointense areas on T!WI which is hyperintense on T2 WI may demonstrate fibrovascular tissue. MRI is mostly useful when searching the complications.The complications of the disease are fractures, osteoarthritis, sarcomatous transformation, cardiovascular complications such as systemic hypertension, heart failure...Treatmment of the disease consists of medical and surgical treatment. Analgesics are used to reduce bone pain, bisphosphonate or calcitonin can be used to slow the progression of the disease.