Osteoporosis is a disease characterized by decrease in bone density of normally mineralized bone; according to the WHO definition as a bone mineral density that is 2.5 standard deviations or more below the mean peak value in young, healthy adults. Special techniques to measure bone mineral density include dual energy X-ray absorptiometry and quantitative CT. Routine radiographs are less sensitive; substantial bone loss (approximately 30% to 40%) must occur to detect osteoporosis. Back pain, thoracic kyphosis and vertebral crush fractures are common symptoms. Patients have also increased risk for spontaneous fractures of the femoral neck. Primary osteoporosis affects patients older than 50 years and postmenopausal women with estrogen deficiency. Secondary causes include endocrine disorders, gastrointestinal disturbances, drugs (corticosteroids), and immobilization.
Cortical and trabecular bone is decreased with trabecular bone more severely affected. In normal bone, trabeculae are broad and continuous. In osteoporosis, trabeculae are rare, thin a short, separated by widened intertrabecular spaces.
Osteoporosis, HE 40x (12104)
Osteomyelitis is an inflammatory condition of bone caused by an infectious agent. Patients usually present with pain and fever. Any bone can be affected.
The bone may contain pus. Portions of bone may undergo necrosis and separate (sequestrum).
In acute osteomyelitis, the medullary cavity is richly vascularized and contains polymorphonuclear leukocytes with areas of necrosis and granulation tissue. Chronic osteomyelitis shows plasma cell infilration and bone marrow replacemens with fibrous tissue. Bone trabeculae are thickened.
Osteomyelitis, HE 40x (12499)
Paget disease causes progressing skeletal deformities associated with bone thickening. Mostly affected are pelvis, skull, femur and tibia of patients in the fifth and sixth decades.
Irregular thickening an coarsening of the cortical bone and medullary cancellous bone.
Early, osteoclasts are prominent and form Howship lacunae. Later, bone trabeculae are irregularly thickened. Blue cement lines form a mosaic pattern.
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