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Pathology The Bones, Joints, Soft Tissues


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What is osteogenesis imperfecta
A group of heritable diseases characterized by abnormal type I collagen
How many types of osteogenesis imperfecta are there
4 (types I to IV)
What is the usual clinical presentation of osteogenesis imperfecta
Multiple fractures, often with minimal trauma
Besides bone, what else is affected in osteogenesis imperfecta
Teeth, skin, eyes
What are the characteristic eye findings in osteogenesis imperfecta
Blue sclerae
What are the radiographic findings in osteogenesis imperfecta
Thin and osteopenic bones, often with many foci of fracture callus
What is osteopetrosis
An inherited disorder characterized by abnormally dense bone
What causes osteopetrosis
Failure of osteoclastic cells by an unknown mechanism
What are 2 other names for osteopetrosis
Marble bone disease
Alber-Schonberg disease
Why the name “marble bone” disease for osteopetrosis
Bones look short and block-like, and are radiodense, like marble
What is the common clinical presentation of osteopetrosis
Multiple fractures
Why are multiple fractures common in osteopetrosis
Although bone is hyperdense, it is intrinsically disorganized. Consequently, it is weaker
What are 2 common conditions associated with osteopetrosis
Anemia due to decreased marrow space
Blindness, deafness, and other cranial nerve involvement due to narrowing of neural foramina
What are the 2 genetic variants of osteopetrosis
AR and AD
What variant of osteopetrosis is most severe
The AR variant is fatal in infancy
What is osteoporosis
A decrease in bone mass
What causes osteoporosis
Impaired synthesis or increased resorption of bone matrix
Name 5 states with which osteoporosis is associated
Physical inactivity
Calcium deficiency
Describe the pathophysiology associated with osteoporosis of the elderly
A continuous loss of bone occurs at the trabecular and cortical layers due to increased resorption
What commonly prescribed drug induces osteopenia
What commonly results from osteopenia
What are the calcium and phosphorus levels in the blood in patients with osteoporosis
What is seen radiographically in patients with osteoporosis
Diffuse radiolucency of bone
What is the treatment for osteoporosis
No cure. Calcium supplements, exercise, and estrogen therapy (in some patients) help reduce the risk, however
What is the effect of PTH on bone
It stimulates the active phase of bone remodeling
What are the two main causes of hyperparathyroidism
Parathyroid hyperplasia and parathyroid adenoma
What are the two clinical features of hyperparathyroidism
Bone pain and hypercalcemia
What are the significant laboratory values in hyperparathyroidism
Calcium >11.5 mg/dl; Phosphorus <2.0 mg/dl
What is seen on bone histologic examination in hyperparathyroidism
An increased number of osteoclasts
After bone is resorbed, what replaces it
Fibrous tissue
What abnormality is often seen in the fibrous tissue of resorbed bone
Hemosiderin pigment
What are the fibrous tissue lesions seen in resorbed bone called
Brown tumors
How is hyperparathyroidism treated
By removal of the parathyroid lesion
How does hypoparathyroidism affect bone
It decreases the turnover rate
What is the most common reason for hypoparathyroidism
Surgical removal of parathyroid glands
What are the clinical signs of hypoparathyroidism
Signs of hypocalcemia, including soft tissue ossification and calcification, abnormal dentition, and otoscleorosis
What is seen on bone histologic examination in hypothyroidism
Active osteoblasts and lack of osteoclasts
What is the treatment for hypoparathyroidism
Administration of PTH or vitamin D
What is osteomalacia
A bone abnormality caused by defective calcification of osteoid matrix
What causes osteomalacia
Vitamin D deficiency
In what age group does osteomalacia typically occur
What can osteomalacia mimic radiographically
How is osteomalacia diagnosed
By bone biopsy
What is the treatment for osteomalacia
Correct vitamin D deficiency
What is osteomalacia called when secondary to renal disease
Renal osteodystrophy
Define rickets
Bone abnormality caused by defective calcification of osteoid matrix and increased thickness of epiphysial growth plates
What causes rickets
Vitamin D deficiency
Describe the difference between rickets and osteomalacia
Osteomalacia occurs in adults, rickets in children. Because bone growth is not complete in patients with rickets, skeletal deformities are common
What are six clinical manifestations of rickets
Craniotabes—thickening and softening of occipital and parietal bones
Late closing of fontanelles
Rachitic rosary—costochondral swelling
Harrison groove—depression of insertion site of diaphragm into rib cage
Pigeon breast—protrusion of sternum
Short stature caused by spinal deformity
What is the treatment for rickets
Correction of vitamin D deficiency
Define scurvy
Bone abnormality characterized by impaired osteoid matrix formation
What causes scurvy
Vitamin C deficiency
How does vitamin C deficiency lead to impaired bone formation
Failure of praline and lysine hydroxylation required for collagen synthesis
Name three clinical characteristics of scurvy
Subperiosteal hemorrhage
Epiphysial cartilage not replaced by osteoid
Why does subperiosteal hemorrhage occur with scurvy
Because of increased capillary fragility
What is seen on bone histologic examination in scurvy
Decreased trabecular bone mass and abnormal osteoblasts
What is the treatment for scurvy
Correction of vitamin C deficiency
What is pyogenic osteomyelitis
Infection of the medullary and cortical portions of the bone, including the periosteum
What bones are commonly affected by pyogenic osteomyelitis in children
Long bones
What bones are commonly affected by pyogenic osteomyelitis in adults
What is the usual causative organism of pyogenic osteomyelitis in children
Staph aureus
What are the usual causative organisms (2) of pyogenic osteomyelitis in newborns
Group B β-hemolytic strep
E coli
What is the usual causative organism of pyogenic osteomyelitis in sickle cell anemia patients
Salmonella organisms
What is the usual causative organism of pyogenic osteomyelitis in IV drug abusers
Pseudomonas organisms
How do the causative bacteria of pyogenic osteomyelitis spread in the body
In adults, what is the usual cause of pyogenic osteomyelitis
Complications from surgery and compound fractures
What portion of the bone is most commonly involved initially in pyogenic osteomyelitis
Name 3 reasons for persistent pyogenic osteomyelitis
Necrotic bone acting as a locus for persistent infection
Pyogenic exudate compressing vascular supply of bone
Inflammation in relatively avascular areas of bone
Name 2 clinical symptoms of pyogenic osteomyelitis
Fever, local bone pain
What are significant laboratory test values in pyogenic osteomyelitis
Marked leukocytosis, fever, and increased sedimentation rate
What is a localized bone infection surrounded by granulation tissue called
Brodie abscess
How is a Brodie abscess treated
Drain or debride the abscess
Administer antibiotics
How frequently do flare-ups occur with chronic osteomyelitis
It varies, with intervals of months to years
What is tuberculous osteomyelitis
Bone infection due to spread of tuberculous organisms
How are tuberculous organisms spread
What is tuberculous osteomyelitis with spinal involvement called
Pott disease
What bones does tuberculous osteomyelitis affect
Long bones
Bones of the hands and feet
What happens to bone affected by tuberculous osteomyelitis
Progressive destruction, with little ossification
What is histiocytosis X
A group of disorders affecting other organs systems in addition to bone. It is characterized by proliferation of histiocyte cells
Histiocyte cells are similar to what epidermal cells
Langerhans cells
What are characteristic markers of histiocytic cells
Birbeck granules
What do Birbeck granules look like
Tennis rackets
Name 3 variants of histiocytosis X
Eosinophilic granuloma
Hand-Schuller-Christian disease
Letterer-Siwe disease
What is characteristic of eosinophilic granuloma
Histiocytic proliferation with inflammatory cells, including many eosinophils
What is the clinical presentation of eosinophilic granuloma
Solitary bone lesion
Does extraskeletal involvement occur in eosinophilic granuloma
Yes, commonly in the lung
What is the prognosis in eosinophilic granuloma
Best of all variants of histiocytosis X. Lesions sometimes heal without treatment
What is characteristic of Hand-Schuller-Christian disease
Histiocyte proliferation with inflammatory cells
What is affected in Hand-Schuller-Christian disease
Other tissues
What population is affected by Hand-Schuller-Christian disease
Children less than 5 years old
List the classic triad of Hand-Schuller-Christian disease
Skull lesions
Diabetes insipidus
What is the prognosis in Hand-Schuller-Christian disease
Better than Letterer-Siwe, worse than eosinophilic granuloma
What is characteristic of Letterer-Siwe disease
Widespread histiocyte proliferation
What population is affected by Letterer-Siwe disease
What are 5 clinical findings in Letterer-Siwe disease
Pulmonary involvement
Recurrent infections
What is the course of Letterer-Siwe disease
Aggressive and fatal
What is another name for unicameral bone cyst
Solitary bone cyst
What is the cause of unicameral bone cyst
What population is affected by unicameral bone cysts
Young males
What portion of bone is affected by unicameral bone cysts
Distal ends of long bones
Name 3 clinical signs of unicameral bone cysts
Soft tissue swelling
Occasional fractures
What is seen on radiography of unicameral bone cysts
Radiolucent area with smooth, thin cortex
What is the appearance of unicameral bone cysts on gross pathology
Multiloculated cavity
What is the treatment for unicameral bone cysts
Curettage with insertion of bone chips
What is the prognosis with unicameral bone cysts
Excellent, with few recurrences
What population is affected by aneurysmal bone cysts
Females in 2nd to 3rd decade of life
What portion of bone is usually affected with aneurysmal bone cysts
Metaphysis of long bones
Name the 2 clinical signs of aneurysmal bone cysts
Soft tissue swelling
What is seen on radiography of aneurysmal bone cysts
Circumscribed zone of rarefaction, with extension into soft tissues
What is the size range of aneurysmal bone cysts
Up to 20 cm
What is the gross pathology of aneurysmal bone cysts
Bone is greatly distorted with irregular outlines. It appears spongy, with cystic spaces of various sizes
Give 2 histologic differential diagnoses of aneurysmal bone cysts
Giant cell tumor of bone
Telangiectatic osteosarcoma
How are aneurysmal bone cysts treated
Removal of entire lesion with insertion of bone chips
What is the prognosis with aneurysmal bone cysts
Recurrences occur 20% to 30% of the time
Fibrous dysplasia most commonly affects what bones
Ribs, femur, tibia, maxilla
Is fibrous dysplasia monostotic or polyostotic
80% monostotic; 20% polyostotic
Polyostotic lesions are part of what syndrome
Albright syndrome
What bone complications occur in fibrous dysplasia
Deformity secondary to repeated fractures
Describe the radiographic appearance of fibrous bone dysplasia
Well-defined zones of rarefaction surrounded by narrow rims of sclerotic bone
Describe the major histologic feature of fibrous dysplasia
Proliferation of fibroblasts, which produce a dense collagenous matrix
What is the treatment for monostotic bone lesions
Curettage or local resection
What is the treatment for polyostotic bone lesions
Conservation (nonsurgical), because lesions stop growing after puberty
What is another name for osteochondroma
Define osteochondroma
Bony growth covered by a cartilaginous cap
What is osteochondroma’s claim to fame
Most common benign tumor of bone
Where does osteochondroma originate
In the metaphysis
What are the 2 most frequent locations for osteochondroma
Distal femur
Proximal tibia
What population is most commonly affected by osteochondroma
Males under 25 years of age
Does osteochondroma undergo transformation to a malignant tumor
Describe the clinical symptoms of osteochondroma
Pain and compression of adjacent structures
What is the prognosis of osteochondroma
Excellent. Resection is usually curative
What is giant cell tumor
Benign tumor characterized by multinucleated giant cells and fibrous stroma
Where does giant cell tumor originate
Epiphysis of long bones
What are the 2 most frequent locations of giant cell tumor
Distal femur
Proximal tibia
How does giant cell tumor appear radiographically
Soap bubble appearance
What population is most commonly affected by giant cell tumor
Females 20 to 40 years old
What is the course of giant cell tumor
Although benign, it is locally aggressive
What is the prognosis of giant cell tumor
Frequently recurs after local curettage
What is enchondroma
Benign intramedullary cartilaginous neoplasm
Where does enchondroma most frequently occur
Hands and feet
What population is most commonly affected by enchondroma
All age groups
What is osteoma
Benign tumor of mature bone
What are the 2 most frequent locations of an osteoma
Facial bones
What population is most commonly affected by osteoma
Males of any age
Osteoma occurring as multiple lesions, with intestinal polyps and soft tissue tumors, is known by what name
Gardner syndrome
What are the clinical features of osteoma
It is asymptomatic, unless drainage of paranasal sinus is blocked
What is the prognosis of osteoma
Excellent. Resection is curative
What is osteoid osteoma
Neoplastic proliferation of osteoid and fibrous tissue
What are the most frequent locations of osteoid osteoma
Ends of diaphysis of femur or tibia
What population is most commonly affected by osteoid osteoma
Males less than 25 year old
What are the clinical features of osteoid osteoma
Increasing pain, worse at night, relieved by aspirin
How does osteoid osteoma appear radiographically
Central radiolucent area surrounded by sclerotic bone
What is the central radiolucent area in an osteoid osteoma called
What is the nidus of osteoid osteoma, microscopically
Osteoblasts, calcification, and multinucleate giant cells
What is the prognosis for osteoid osteoma
Excellent. Resection of nidus and sclerotic bone is curative
Name the 2 most frequent locations of osteoblastoma
Vertebrae and long bones
What population is most commonly affected by osteoblastoma
Males under 30
What are the clinical features of osteoblastoma
Usually none
Radiographically, how does osteoblastoma appear
Well-circumscribed lesion surrounded by sclerotic bone
What treatment for osteoblastoma allows the best prognosis
Results are excellent when the lesion is removed by curettage
Give another name for osteosarcoma
Osteogenic sarcoma
State osteosarcoma’s claim to fame
Osteosarcoma is the most common primary malignant tumor of bone
Define osteosarcoma
Malignant osteoid and bone-producing neoplasm
What causes osteosarcoma
The cause is unknown
Name the 2 most frequent locations of osteosarcoma
Distal femur and proximal tibia
What population is most commonly affected by osteosarcoma
Males 10-20 years old
What are the clinical features of osteosarcoma
Pain, swelling, and pathologic fractures
What are the significant laboratory values of osteosarcoma
A 2-3 fold increase in alkaline phosphatase levels
Radiographically, elevation of periosteum is called what
Codman triangle
How does osteosarcoma spread
Name the 4 factors predisposing to osteosarcoma
Paget disease
Ionizing radiation
Bone infarcts
Familial retinoblastoma
How does osteosarcoma appear on gross pathology
Large necrotic and hemorrhagic mass
What is the microscopic appearance of osteosarcoma
Malignant stroma containing osteoid and bone
How is osteosarcoma treated
Surgical amputation of affected limb, and adjunctive chemotherapy
What is the prognosis for osteosarcoma
Poor; 5 year survival rate is 5% to 20%
What is chondrosarcoma
Malignant cartilaginous neoplasm
Name the 4 most frequent locations of chondrosarcoma
Proximal femur, proximal humerus, pelvis, spine
What population is most commonly affected by chondrosarcoma
Males 30-60 years old
Name three clinical features of chondrosarcoma
Pain, swelling, and presence of mass for several years
Radiographically, how does chondrosarcoma appear
Cortical destruction with occasional medullary involvement
From what two preexisting cartilaginous tumors can chondrosarcoma arise
Multiple familial osteochondromatosis
Multiple enchondromatosis
How does chondrosarcoma appear on gross pathology
Lobulated white or gray mass, with mucoid material and calcification
What is chondrosarcoma’s microscopic appearance
Poorly developed cartilage cells with anaplastic cells
What is the treatment for chondrosarcoma
Total resection, if possible
What is the prognosis for chondrosarcoma
Chondrosarcoma is slow growing, but has a high tendency to recur; 10 year survival rate is 50-60%
What is Ewing sarcoma
Undifferentiated round cell malignant tumor
In what 4 areas does Ewing sarcoma occur most often
Long bones, pelvis, scapula, ribs
What population is most commonly affected with Ewing sarcoma
Males less than 15 years
What are the clinical features of Ewing sarcoma
Pain, swelling, and presence of mass for several years
How does Ewing sarcoma appear radiographically
Destructive appearance
What does subperiosteal reactive new bone resemble
Onion skin
The early phase of Ewing sarcoma mimics what other disease
Acute osteomyelitis
What genetic defect is present in Ewing sarcoma
11,22 translocation
Where does Ewing sarcoma arise
Undifferentiated mesenchymal cells of the medullary cavity
How does Ewing sarcoma appear on gross pathology
Hemorrhagic and necrotic destruction of medullary cavity
Microscopically, what is seen with Ewing sarcoma
Undifferentiated small round cells in sheets or cords
How is Ewing sarcoma treated
Amputation of limb; possibly chemotherapy
What is the prognosis with Ewing sarcoma
Poor. Malignant course with early metastases; the 5 year survival rate is 0-12%
Give another name for osteitis deformans
Paget disease of the bone
Define osteitis deformans
Bone disease characterized by abnormal bony architecture with increases in osteoblastic and osteoclastic activity, and a “high turnover rate”
Name the five most common locations of osteitis deformans
Spine, pelvis, skull, femur, and tibia
What population is most commonly affected with osteitis deformans
Elderly persons
What causes osteitis deformans
Cause is unknown; an infectious nature is postulated
Describe the clinical features of osteitis deformans
Pain, fracture, and skeletal deformities; deafness when skull is involved; short stature when spine is involved
Is osteitis deformans monostotic or polyostotic
Microscopically, how does osteitis deformans appear
Marked medullary fibrosis; disorganization of normal trabecular pattern
What is the treatment for osteitis deformans, and why?
Calcitonin or one of the diphosphonates. They decrease resorption, and thus decrease the high turnover rate
What is avascular necrosis
Necrosis of bone, usually the femoral head, caused by infarction
Give 3 possible causes of avascular necrosis
Decompression syndrome (the bends)
Sickle cell anemia
Radiologically, what is seen with avascular necrosis
Reparative foci replacing necrotic bone
With what other conditions is avascular necrosis commonly associated
Corticosteroid treatment
What is the treatment for avascular necrosis
When avascular necrosis occurs in the femoral head of children, what is it called
Legg-Calve’-Perthes disease
What disease is characterized by pain in weight-bearing joints, is worse after use, has crepitation with motion, no signs of inflammation, and is seen in the middle-aged population
Osteoarthritis, aka degenerative joint disease
What are signs of osteoarthritis on x-ray
Joint space narrowing, osteophytes
What are Herberden’s nodules
Palpable DIP joints with osteophytes
What are Bouchard’s nodules
Palpable PIP joints with osteophytes
What are some treatments of osteoarthritis
NSAIDs and weight reduction to reduce strain on joints
A 4 year old boy presents with arthralgias, soft hyperextensible skin, corneal and scleral abnormalities, joint laxity, and easy bruising. Diagnosis?
Ehlers-Danlos syndrome
A 32 year old female presents to your office complaining of morning stiffness for greater than 1 hour, pain in joints bilaterally, with fatigue and hand deformations over time. Diagnosis?
Rheumatoid arthritis
Which joints are most commonly involved in RA
Wrists, PIP, and metacarpophalangeal
What are some common findings with RA
Pleural effusions
Subcutaneous nodules
Which lab test should you order when you suspect RA
Rheumatoid factor
What is rheumatoid factor
Immunoglobin M antibody to fragment crystallizable (Fc) portion of IgG
What is the name for the chronic inflammation of cartilage found in RA
What disease would be expected in a young woman that suffers with RA-like symptoms (polyarthritis), leukopenia, leg ulcers, and splenomegaly?
Felty’s syndrome
What disease is similar to RA (bilateral joint pain, fever) but is seen in children, along with rash and hepatosplenomegaly
Still’s disease (juvenile RA)
*Kids can’t sit Still when their joints hurt
What is different about pediatric RA
It is often RF negative
A 5 year old child presents with complaints in two joints. Which disease is this
Pauciarticular juvenile RA
What is a child with pauciarticular RA at risk for
Iritis (do slit-lamp test)
A 43 year old male presents to your clinic with a history of falling on his knee two days ago. Since then, the knee has become red, swollen, and warm. Diagnosis?
Septic joint
How can you diagnose septic joint
Arthrocentesis with high white blood cells/ neutrophil count and Gram’s stain
What is the most common causative organism of septic joint
Staphylococcus aureus
What are some common organisms that are found uniquely in the joints of infants and young children
Group B streptococci
Haemophilus influenzae
What are some common organisms associated with implantable devices and prosthetics
Staph aureus
Staphylococcus epidermidis
Gram-negative bacilli
A 23 year old male, sexually active college student arrives at your clinic complaining of a swollen red knee and urethritis. What organism is the most likely
Neisseria gonorrhoeae
How is the diagnosis made in a patient with gonorrhea
Urethral swab
How do you treat gonorrhea
Which organism should be suspected in a patient with diabetes and osteomyelitis
Which organism should be suspected in a sickle cell patient with osteomyelitis
A 65 year old white male presents to clinic with a 2 hour history of sudden onset of extreme pain in his great toe. What disease should be suspected in this patient
What is podagra
Gout of the metatarsophalangeal joint of the big toe
What other findings should be looked for in a patient with gout
Tophi, subcutaneous deposits of uric acid crystals
How do tophi appear on x-ray
“Punched out” lesions
What lab tests help to diagnose gout
Uric acid level
Joint fluid aspiration of needle-shaped crystals with negative birefringence
What are contributing factors for gout
Thiazide diuretics
Lesch-Nyhan syndrome
Diets with high protein and alcohol
What is the treatment for gout
Acute—Colchicine, NSAIDs
What diseases are associated with pseudogout
A 12 year old presents with migratory polyarthritis, rash, fever, and general malaise. She recalls having a sore throat about 3 weeks ago but did not get treatment. Diagnosis?
Acute rheumatic fever
What are the Jones criteria of rheumatic fever
Erythema marginatum
Verrucous valvular vegetations
Erythrocyte sedimentation rate increase
Subcutaneous nodules
Chorea (Sydenham’s)
Preceded by Streptococcus infection

*FEVERS and Chorea preceded by a Streptococcus infection

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