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Pathology > Chapter 18 ( Musculoskeletal ) > Flashcards

Chapter 18 ( Musculoskeletal ) Flashcards

1
Q

Achondroplasia mechanism ?

A

Impaired cartilage proliferation in the growth plate
Due to an activating mutation in FGFR3 ( overexpression of FGFR3 inhibits growth )
Autosomal dominant
Most mutations are sporadic and related to incresed paternal age

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2
Q

Presentation of Achondroplasia ?

A

Short extremities : due to endochondral bone formation
Normal sized head and chest : because intramembranous bone formation is not affected
Mental function , life span , fertility are not affected

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3
Q

Mechanism of Osteopetrosis ? Ttt ?

A

Inherited defect of bone resorption resulting in abnormally thick heavy bone that fractures easily
Due to poor osteoclastic activity

Carbonic anhydrase ll mutation leads to loss of the acidic environment required for bone resorption

Ttt : bone marrow transplant

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4
Q

Osteoclasts are derived from ?

A

Monocytes

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5
Q

Lab findings of osteomalacia ?

A

⬇️ serum Ca
⬇️ serum phosphate
⬆️ PTH
⬆️ alkaline phosphatase

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6
Q

Mechanism of osteoporosis ?

A

Reduction in trabecular bone mass

Results in porous bone with increased risk for fractures

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7
Q

How to distinguish osteoporosis from osteomalacia ?

A

All labs values are normal in osteoporosis !!

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8
Q

Mechanism of Paget disease of bone ? Stages ?

A

Imbalance between osteoclast and osteoblast function in late adulthood ( >60 y )
Localized process

Stages :
1- Osteoclastic stage
2- Mixed osteoclastic and osteoblastic stage
3- Osteoblastic stage

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9
Q

Paget disease of bone gross and micro ? Clinical features ? Ttt ?

A

Gross : thick sclerotic bone that fractures easily
Micro : a mosaic pattern of lamellar bone

Clinical features :
Bone pain
Increasing hat size
Hearing loss
Lion like facies 
Isolated elevated alkaline phosphatase

Ttt : calcitonin and bisphophonates

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10
Q

Complications of Paget disease of bone ?

A

High output cardiac failure ( due to formation of AV shunts in bone )
Osteosarcoma

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11
Q

Mechanism of osteomyelitis ? Causative organisms ?

A

Most commonly bacterial arises by hematogenous spread :
In children : transient bacteremia seeds Metaphysis
In adults : open wound bacteremia seeds Epiphysis

Causes :
Staph aureus ( most common 90% )
N gonorrhea ( sexually active young adults )
Salmonella ( sickle cell anemia )
Pseudomonas ( diabetics or IV drug abusers )
Posteurella ( with cat/dog bites or scratches )
TB ( often involves vertebrae )

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12
Q

Causes of avascular aseptic bone necrosis ?

A

Trauma or fracture ( most common )
Steroids
Sickle cell anemia
Caisson disease

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13
Q

Gardner syndrome ?

A

1- Familial adenomatous polyposis
2- Fibromatosis of retroperitoneum
3- Osteoma

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14
Q

Osteoid osteoma arises from ? Site ? Presentation ? Imaging ?

A

Osteoblasts surrounded by rim of reactive bone

Cortex of long bones in the diaphysis

Presents in young adults as bone pain that resolves with aspirin

Imaging : a bony mass < 2cm with radiolucent core ( osteoid )

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15
Q

How to distinguish between osteoblastoma and osteoid osteoma ?

A

Osteoblastoma is :
Larger > 2cm
Arises in vertebrae
Presents as bone pain that DOES NOT respond to aspirin

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16
Q

Most common benign tumor of bone ?

A

Osteochondroma

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17
Q

Osteochondroma description ? Site ?

A

Tumor of bone with an overlying cartilage cap

From a lateral projection of the metaphysis ( bone is continuous with the marrow space )

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18
Q

Osteosarcoma arises from ? Risk factors ? Site ? Presentation ? Imaging ? Histology ?

A

Osteoblasts

Risk factors :
Familial retinoblastoma
Paget disease of bone
Radiation

In the metaphysis of longe bone usually around the knee

Seen in teenagers as pathologic fracture or bone pain with swelling

Imaging : a destructive mass with a Sun burst appearance and lifting of the periosteum ( Codman triangle )

Histo : pleomorphic cells that produce osteoid

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19
Q

Giant cell tumor comprised of ? Site ? Imagine ? Behavior ?

A

Multinucleated giant cells and stromal cells

In the epiphysis of long bones usually around the knee

Imaging : Soap bubble appearance

Behavior : LOCALLY AGGRESSIVE but may RECURE

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20
Q

Ewing sarcoma ? Site ? Seen in ? Imaging ? Histology ? Associated with which mutation ?

A

Malignant proliferation of poorly differentiated cells derived from NEUROECTODERM

In the diaphysis of long bones

Seen in male children < 15y

Imaging : Onion skin appearance

Histo : small round blue cells that resembles lymphocytes

Mutation : t(11;22)

21
Q

Chondroma site ?

A

In the medulla of small bones of the hands and feet

22
Q

Chondrosarcoma site ?

A

In the medulla of the pelvis or central skeleton

23
Q

In synovial joints , articular sites of adjoining bones is made of ?

A

Hyaline cartilage ( type ll collagen )

24
Q

The synovium in synovial joints secrets ? Its function ?

A

Fluid rich in hyaluronic acid to lubricate the joints and facilitate smooth motion

25
Q

Pathologic features of osteoarthritis ?

A

1- Disruption of the cartilage that lines the articular surface , fragments of cartilage floating in the joint space are called ( joint mice )
2- Eburnation of the subchondral bone
3- Osteophyte formation ( reactive bone outgrowths ) :
in DIP —> Heberden nodes
in PIP —> Bouchard nodes

26
Q

Rheumatoid arthritis associated with ? Hallmark ? Lab findings ?

A

HLA-DR4

Hall mark is Synovitis leads to formation of Pannus ( inflamed granulation tissue )
Leads to destruction of cartilage and ankylosis og joints

Lab findings :
IgM autoantibody against Fc portion of IgG ( Rheumatoid factor , marker of tissue damage and disease activity )
Neutrophils and high proteins in synovial fluid

27
Q

Rheumatoid nodules histology ? Site ?

A

Central zone of necrosis surrounded by epithelioid histiocytes

In the skin and visceral organs

28
Q

Seronegative spondyoarthropathies associated with ?

A

HLA-B27

29
Q

Extraarticular manifestations of ankylosing spodyloarthritis ?

A

Uveitis

Aortitis ( leading to aortic regurgitation )

30
Q

Reiter syndrome triad ? Cause ?

A

Cant see , pee , climb a tree
Arthritis
Urethritis
Conjunctivitis

In young adults weeks after GI or Chlamydia trachomatis infection

31
Q

Psoriatic arthritis site ? Characteristic ?

A

Axial and peripheral joints

DIP joints of hands and feet are most commonly affected leading to Sausage finger or toes

32
Q

Infectious arthritis causes ? Labs ?

A 
N gonorrhea ( most common cause )
S aureus ( 2nd most common cause )

Increased WBCs count
Elevated ESR

33
Q

Gout is deposition of what in tissues ?

A

Monosodium urate crystals

34
Q

Secondary gout is seen with ?

A

1- leukemia and myeloproliferative disorders
2- Lesch-Nyhan syndrome ( x linked HGPRT deficiency )
3- Renal insufficiency

35
Q

Precipitating factors of arthritis in Acute gout ?

A

Alcohol

Consumption of meat

36
Q

Chronic gout leads to ?

A

Development of Tophi ( white chalky aggregates of uric acid crystals with fibrosis and giant cell reaction in the soft tissue and joints

Renal failure ( urate nephropathy )

37
Q

Labs of gout ?

A

Hyperuricemia

Synovial fluid shows needle shaped crystals with negative birefringence under polarized light

38
Q

Pseudogout due to deposition of ? Labs ?

A

Calcium pyrophosphate dihydrate ( CPPD )

Labs : synovial fluid shows rhomboid shaped crystals with weakly positive birefringence under polarized light

39
Q

Dermatomyositis can be associated with ? Clinical features ? Labs ?

A

Carcinoma ( gastric carcinoma )

Clinical features :
Bilateral proximal muscle weakness
Rash of the upper eyelids ( Heliotrope rash )
Malar rash
Res papules on the elbow , knuckles and knees ( Gottron rash )

Labs :
1- ⬆️ Creatine Kinase
2- Positive ANA and Anti-Jo-1 antibody
3- Perimysial inflammation ( CD4 T cells ) with Perifascicular atrophy on biopsy

40
Q

Polymyositis on biopsy ?

A

Endomysial inflammation ( CD8 T cells ) with necrotic muscle fibers

41
Q

Function of Dystrophin ?

A

Important for anchoring the muscle cytoskeleton to the extracellular matrix

42
Q

Labs of Duchenne ?

A

⬆️ Creatine Kinase

43
Q

Myasthenia gravis associated with ?

A

Thymic hyperplasia or thymoma

Thymectomy improves symptoms

44
Q

Lambert-Eaton syndrome mechanism ?

A

Antibodies against presynaptic Ca channels of the neuromuscular junction
Arises as paraneoplastic syndrome most commonly due to small cell carcinoma of the lung
Leads to impaired acetylcholine release

45
Q

Clinical features of Lambert-Eaton syndrome ?

A

Procimal muscle weakness that improves with use
Eyes are usually spared
Anticholinesterase agents do not improve symptoms
Resolves with resection of the causative tumor ( small cell carcinoma of the lung )

46
Q

Most common benign soft tissue tumor in adults ?

A

Lipoma

47
Q

Most common malignant soft tissue tumor in adults ? Characteristic cell ?

A

Liposarcoma

Lipoblast

48
Q

Cardiac rhabdomyoma is associated with ?

A

Tuberous sclerosis

49
Q

Most common malignant soft tissue tumor in children ? Characteristic cell ? Most common site ?

A

Rhabdomyosarcoma

Rhabdomyoblast

The head and neck
Vagina is the classic site in young girls

Pathology (18 decks)

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