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Pathology of the musculoskeletal system 1

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Pathology of the musculoskeletal system 1

  1. 1. PATHOLOGY OF THE MUSCULOSKELETAL SYSTEM BY CHAPIMA F. MSc. PTH - Clinical Pathology (UNZA), B.Sc. (UNZA) Sunday, April 26, 2015 1
  2. 2. Lecture outline Bones  Congenital diseases of bone  Acquired diseases of bone development  Fractures  Osteonecrosis  Osteomyelitis  Metabolic bone disease  Bone tumorsSunday, April 26, 2015 2
  3. 3. CONGENITAL DISEASES OF BONE 1. Osteogenesis Imperfecta Definition  Osteogenesis imperfecta (OI) (brittle bone disease) is a genetic disorder characterized by hard and easily broken bones often from little or no apparent cause.  It is due to a genetic defect in collagen type I affecting the body’s ability to make strong bones. Sunday, April 26, 2015 3
  4. 4. Clinical features Type I  Most common and mildest type of OI.  Bones fracture easily.  Normal or near-normal stature.  Loose joints and muscle weakness.  Sclera usually have a blue, purple, or gray tint.  Triangular face.  Hearing loss possible, often beginning in early 20s or 30s.Sunday, April 26, 2015 4
  5. 5. Clinical features………….. Type II  Most severe form.  Numerous fractures and severe bone deformity.  Small stature with underdeveloped lungs. Sunday, April 26, 2015 5
  6. 6. Clinical features………….. Type III  Short stature.  Barrel-shaped rib cage.  Bone deformity, often severe.  Brittle teeth possible.  Hearing loss possible. Sunday, April 26, 2015 6
  7. 7. 2. Achondroplasia  Achondroplasia means "without cartilage formation,“.  It is a genetic condition characterized by a short stature caused by a defect in converting cartilage into bones (ossification) particularly in the long bones.  It is the most common cause of dwarfism. Sunday, April 26, 2015 7
  8. 8. Causes  It is caused by mutations in the fibroblast growth factor receptor 3 (FGFR3) gene.  This gene provides instructions for making a protein called FGFR3 protein which is involved in the development and maintenance of bones.  This genetic change causes the receptor to be very active, which leads to the disturbances in the ossification of bones.  Achondroplasia is inherited in an autosomal dominant pattern.Sunday, April 26, 2015 8
  9. 9. Clinical features  Clients have short stature  The average height of an adult male is 131 cm adult females is 124 cm.  Have an average-size trunk,  Short arms and legs with particularly short upper arms and thighs,  Limited range of motion at the elbows  A big head (macrocephaly) with a prominent forehead.Sunday, April 26, 2015 9
  10. 10. ACQUIRED DISEASES OF BONE DEVELOPMENT 1. Fractures  A fracture is a broken bone. A bone may be completely fractured or partially fractured in any number of ways. Cause  The most common causes of fractures are:  Trauma. A fall, a motor vehicle accident, or trauma during a football game can all result in fractures. Sunday, April 26, 2015 10
  11. 11. Cause…………..  Osteoporosis. This disorder weakens bones and makes them more likely to break (pathological fractures).  Overuse. Repetitive motion can tire muscles and place more force on bone.  This can result in stress fractures. Stress fractures are more common in athletes. Sunday, April 26, 2015 11
  12. 12. Common types of fractures  Stable fracture. The broken ends of the bone line up and are barely out of place.  Open or compound fracture. The skin is pierced by the bone that breaks the skin at the time of the fracture.  The bone may or may not be visible in the wound. Sunday, April 26, 2015 12
  13. 13. Common types …………..  Transverse fracture. This type of fracture has a horizontal fracture line.  Oblique fracture. This type of fracture has an angled pattern.  Comminuted fracture. In this type of fracture, the bone shatters into three or more pieces.Sunday, April 26, 2015 13
  14. 14. Symptoms  Pain on the affected area  Un able to move the injured limb. Other common symptoms include:  Swelling and tenderness around the injury area  Bruising  Deformity — a limb may look "out of place" or a part of the bone may puncture through the skinSunday, April 26, 2015 14
  15. 15. 2. Osteonecrosis  Osteonecrosis (ON) is a focal infarct of bone that may be caused by specific etiologic factors or may be idiopathic. Causes/ Risk factors  No one is sure what causes the disease. Risk factors include;  Long-term steroid treatment  Alcohol abuse  Joint injuries  Having diseases such as arthritis and cancerSunday, April 26, 2015 15
  16. 16. Pathophysiology  Mechanisms of non-traumatic ON include embolization by blood clots or lipid droplets.  This leads to the death of osteocytes and bone marrow.  After the vascular insult, the repair processes attempt to remove necrotic bone and marrow and replace them with viable tissue.  If the infarct is small, this process may succeed. Sunday, April 26, 2015 16
  17. 17. Pathophysiology…………..  However, in some patients, the process is not successful and the infarct gradually collapses.  The overlying articular surface becomes flattened and irregular, causing increased pain and eventually leading to osteoarthritis.Sunday, April 26, 2015 17
  18. 18. Symptoms and Signs  Patients may remain asymptomatic for weeks to months after the vascular insult.  Pain then develops gradually with progressive collapse of the joint  Pain increases and is worsened by motion and weight bearing and is relieved by rest.Sunday, April 26, 2015 18
  19. 19. 3. Osteomyelitis  Osteomyelitis is an infection in a bone. Causes  Most cases of osteomyelitis are caused by Staphylococcus aureus (Pyogenic Osteomyelitis) and Mycobacterium tuberculosis (Tuberculous Osteomyelitis)  Micro – organisms can enter a bone in 3 ways;  Via the bloodstream. infection in other parts of the body — for example pneumonia or a urinary tract infection — can travel through bloodstream to a bone.Sunday, April 26, 2015 19
  20. 20. Causes…………..  From a nearby infection. Severe puncture wounds can carry germs deep inside the body.  If such an injury becomes infected, the germs can spread into a nearby bone.  Direct contamination. This may occur in cases of fractures.  Direct contamination can also occur during surgeries to replace joints or repair fractures.Sunday, April 26, 2015 20
  21. 21. Risk factors  Recent injury or orthopedic surgery  Poorly controlled diabetes  Peripheral arterial disease, often related to smoking  Sickle cell disease  Chemotherapy Sunday, April 26, 2015 21
  22. 22. Pathophysiology  Osteomyelitis tends to occlude local blood vessels, which causes bone necrosis and spread of infection to the bones.  Infection may inflate through the bone cortex and spread under the periosteum, with formation of subcutaneous abscesses that may drain spontaneously through the skin. Sunday, April 26, 2015 22
  23. 23. Signs and symptoms  Fever or chills  Irritability or lethargy in young children  Localized bone pain  Swelling, warmth and redness over the area of the infection  Sometimes osteomyelitis causes no signs and symptoms or has signs and symptoms that are difficult to distinguish from other problems.Sunday, April 26, 2015 23
  24. 24. Complications  Osteonecrosis - Bone death  Septic arthritis  Impaired growth  Skin cancer. If osteomyelitis has resulted in an open sore that is draining pus, the surrounding skin is at higher risk of developing squamous cell cancer. Sunday, April 26, 2015 24
  25. 25. METABOLIC BONE DISEASE 1. Osteoporosis  Osteoporosis AKA “porous bone” is a disease characterized by increased sponginess of the skeleton resulting from reduced bone mass. Sunday, April 26, 2015 25
  26. 26. Classifications  Osteoporosis can be primary or secondary disorder due to some other factor. Primary disorder can further be classified as;  Type 1 or postmenopausal osteoporosis is associated with decreased levels of estrogen and has a greater effect on trabecular than cortical bone.  Type 2 or senile osteoporosis is a consequence of aging and is often augmented by inadequate calcium and vitamin D intake.Sunday, April 26, 2015 26
  27. 27. Pathophysiology  Bone is continually being formed and resorbed.  Osteoblasts and osteoclasts (cells that resorb bone) are regulated by parathyroid hormone (PTH), calcitonin, estrogen, vitamin D, various cytokines, and other local factors such as prostaglandins.  Peak bone mass in men and women occurs by the mid 20s.  Normally, bone formation and resorption is closely balanced.Sunday, April 26, 2015 27
  28. 28. Pathophysiology………..  Blacks reach higher bone mass than whites  Men have higher bone mass than women.  After achieving peak for about 10 years, bone loss occurs at a rate of about 0.3 to 0.5%/yr.  In menopause, bone loss is accelerated to about 3 to 5%/yr for about 5 to 7 yr and then the rate of loss slows.  Osteoporosis occurs when bone loss exceeds bone formation, resulting in a low bone mass.Sunday, April 26, 2015 28
  29. 29. Pathophysiology……….. Sunday, April 26, 2015 29
  30. 30. Risk Factors  Race (Caucasians > African Americans)  Sex (F > M)  Physical inactivity  Slender body build  Early menopause  Increasing age  Calcium nutritional state - insufficient dietary intake. Sunday, April 26, 2015 30
  31. 31. Signs and Symptoms  Patients with osteoporosis are asymptomatic unless a fracture has occurred. Gross morphology  The trabecular plates become perforated, thinned, and lose their interconnections, leading to progressive micro fractures.Sunday, April 26, 2015 31
  32. 32. 2. Osteomalacia and Rickets  Osteomalacia refers to a softening of bones, often caused by vitamin D deficiency in adults.  Rickets is the softening and weakening of bones in children, usually because of an extreme and prolonged vitamin D deficiency. Sunday, April 26, 2015 32
  33. 33. Pathophysiology  Vitamin D promotes the absorption of calcium and phosphorus from the gastrointestinal tract.  Deficiency of vitamin D makes it difficult to maintain proper calcium and phosphorus levels in bones, which can cause soft bones .  Soft bones are more likely to bow and fracture than are harder and healthy bones.Sunday, April 26, 2015 33
  34. 34. Sign and symptoms  The most common signs and symptoms are bowled legs. Sunday, April 26, 2015 34
  35. 35. 3. Paget’s disease of the bone  Paget's disease is a localized disorder of bone transformation that typically begins with excessive bone resorption followed by an increase in bone formation.  This results in deformity of the affected bones.  The disease occurs worldwide, but is more common in Europe, Australia, and New Zealand.Sunday, April 26, 2015 35
  36. 36. Aetiology and Pathogenesis  The cause is unknown.  However, both genetic and environmental factors (Paramyxovirus) have been implicated.  Paramyxovirus is thought to induce the secretion of IL-6 from fibroblasts and macrophages  IL-6 recruits and activates osteoclasts.  Three phases of Paget disease have been described: lytic, mixed lytic and blastic, and sclerotic.Sunday, April 26, 2015 36
  37. 37. Aetiology and Pathogenesis………. 1. Paget disease begins with the lytic phase, in which normal bone is resorbed by osteoclasts. 2. The second phase, the mixed phase, is characterized by rapid increases in bone formation from numerous osteoblasts. 3. In the final phase of Paget disease, the sclerotic phase, bone formation dominates and the bone that is formed has a disorganized pattern (woven bone) and is weaker than normal adult bone.Sunday, April 26, 2015 37
  38. 38. Risk factors  Age - People older than 40.  Sex - Men are more commonly affected.  Race – whites are more affected.  Family history - close relative with Paget's disease of bones. Sunday, April 26, 2015 38
  39. 39. Signs and symptoms Depend on the part of your body that's affected;  Pelvis - hip pain.  Skull - An overgrowth of bone in the skull can cause hearing loss or headaches.  Spine - nerve roots can become compressed. This can cause pain, tingling and numbness in an arm or leg.  Leg - As the bones weaken, they may bendSunday, April 26, 2015 39
  40. 40. Complications  Fractures - Bones break more easily.  Osteoarthritis - Distorted bones can increase the amount of stress on nearby joints, which can cause osteoarthritis.  Heart failure - Paget's disease may force the heart to work harder to pump blood to the affected areas.  In people with pre-existing heart disease, this increased workload can lead to heart failure.  Hearing loss - caused by narrowing of the auditory foramen or direct involvement of the bones of the middle ear.  Bone cancer. Bone cancer occurs in less than 1 percent of people with Paget's disease.Sunday, April 26, 2015 40
  41. 41. BONE TUMORS Benign bone tumors  Osteochondroma is the most common benign tumor of bone.  This bone growth is covered by a cap of cartilage projecting from the surface of a bone.  It occurs most frequently in men younger than 25 years of age. Sunday, April 26, 2015 41
  42. 42. MALIGNANT BONE TUMORS 1. Osteosarcoma  This is the most common primary malignant tumor of bone.  The peak incidence is in males 10 to 20 years of age.  The tumor occurs most frequently in the metaphysis of long bones. Sunday, April 26, 2015 42
  43. 43. Predisposing factors 1. Paget disease of bone, fibrous dysplasia, chondroma, osteochondroma 2. Ionizing radiation 3. Bone infarcts 4. Familial retinoblastoma presumably due to loss of the Rb suppressor gene locus on chromosome 13.Sunday, April 26, 2015 43
  44. 44. Clinical characteristics  Pain and swelling and occasionally pathologic fracture  A two- to three-fold increase of serum alkaline phosphatase  Lifting of the periosteum by the expanding tumor, which creates a characteristic radiologic appearance known as the Codman triangle.  Early hematogenous spread to the lungs, liver, and brain Sunday, April 26, 2015 44
  45. 45. Gross morphology Grossly, osteosarcomas are gray-white tumors, often exhibiting hemorrhage and cystic degeneration.Sunday, April 26, 2015 45
  46. 46. Chondrosarcoma  This is a malignant cartilaginous tumor.  The peak incidence is in men 30 to 60 years of age.  The neoplasm may arise as a primary tumor or from transformation of preexisting cartilaginous tumors  Characteristic sites of origin include the pelvis, spine, or scapula; the proximal humerus or proximal femur or tibia near the knee. Sunday, April 26, 2015 46
  47. 47. Chondrosarcoma …………….. Sunday, April 26, 2015 47
  48. 48. REFERENCES AND CREDITS  Robbins, S.L, Kumar, V and Abbas, K (2010). Pathologic Basis of Disease (8th Edition). W.B Saunders Company, Philadelphia.  Robbins SL and Kumar V (2007). Basic Pathology (8th Edition).WB Saunders Co. London.  Harsh Mohan, (2010). Textbook of Pathology (6th Edition). Jaypee brothers medical publishers (p) ltd, India  Riede and Werner, Color Atlas of Pathology © 2004 Thieme  Rubin E, Rubin R, Strayer D.S. (2012) Rubin`s Pathology: Clinicopathologic Foundations of Medicine (6th Edition), Lippincott Williams & Wilkins, a Wolters Kluwer business. Philadelphia, PA. Sunday, April 26, 2015 48

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