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Pathoma > Musculoskeletal Pathology > Flashcards

Musculoskeletal Pathology Flashcards

1
Q

Achondroplasia is due to an _________ mutation in ________. This leads to _______.

A

activating mutation in FGFR3 (Fibroblast Growth Factor Receptor 3). overexpression of FGFR3 leads to impaired cartilage proliferation in the growth plate.

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2
Q

What impact does achondroplasia have on development?

A

leads to short extremities with normal sized head and chest. mental function, life span, and fertility are not effected

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3
Q

What causes the pattern of short extremities but normal head and chest with achondroplasia?

A

the activating mutation of FGFR3 leads to impaired endochondral bone formation, while intramembranous bone formation remains unaffected. this is due to embryological development.

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4
Q

what is endochondral bone formation?

A

formation of a cartilage matrix, which is then replaced by bone. it is the mechanism by which long bones grow. this is affected with achondroplasia.

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5
Q

what is intramembranous bone formation?

A

characterized by formation of bone without preexisting cartilage matrix. it is the mechanism by which flat bones, such as the skulls and rib cage, develop. this is not affected with achondroplasia

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6
Q

osteogensis imperfecta is a congenital defect of…

A

bone formation resulting in structurally weak bone

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7
Q

osteogenesis imperfecta is most commonly due to an…

A

autosomal dominant defect in COLLAGEN TYPE I synthesis. (bONE has ONE in it_

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8
Q

what are the clinical features of osteogenesis imperfecta

A
  1. multiple fractures, which can mimic child abuse, but bruising is absent
  2. Blue sclera, which is due to thining of scleral collagen
  3. hearing loss due to the bones of the inner ear easily fracturing.
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9
Q

what is the cause of blue sclera with osteogenesis imperfecta

A

thinning of the scleral collagen, which reveals underlying CHOROIDAL VEINS

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10
Q

Osteopetrosis is due to…

A

inherited defect of bone resorption resulting in abnormally thick, heavy bone that fractures easily. it is due to poor osteoclast function

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11
Q

there are multiple genetic variants with osteopetrosis, which lead to mutations in…

A

carbonic anhydrase II

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12
Q

what is the outcome of loss of carbonic anhydrase II with osteopetrosis

A

inability to convert H2O + CO2 to H2CO3. H2CO3 would then normally be converted to H+ and HCO3- and the H+ would be used to create the acidic environment essential for bone resorption. without this, you cant break down bone

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13
Q

what are the clinical features of osteopetrosis

A 
bone fractures
anemia, thrombocytopenia, leukopenia
vision and hearing impairment
hydrocephalus
renal tubular acidosis
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14
Q

why can anemia, thrombocytopenia, and leukopenia be seen with osteopetrosis?

A

it results in bony replacement of medullary (bone marrow) space, a myelophthisis process (process that replaces marrow space). extramedullary hematopoeisis is also seen due to the loss in medullary space

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15
Q

why is there visual impairment and hearing impairment with osteopetrosis?

A

impingement of cranial nerves by increased bone size

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16
Q

why is there hydrocephalus with oseopetrosis?

A

narrowing of the foramen magnum due to increased bone thickness

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17
Q

how can osteopetrosis cause renal tubular acidosis?

A

the loss of carbonic anhydrase II leads to inability to convert H20 + CO2 to H2CO3, which then becomes H+ and HCO3-. without creating H+ and HCO3-, there will be no bicarb to pump into the blood, leading to acidosis.

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18
Q

what is the treatment for osteopetrosis?

A

bone marrow transplant. this allows for the creation of functional monocytes, which are the precursors to functional osteoclasts.

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19
Q

Rickets and Osteomalacia result from

A

defective mineralization of osteoid. this is due to a low vitamin D level. in children- rickets; in adults- osteomalacia

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20
Q

what is the role of vitamin D

A

raises serum calcium and phosphate by:

  1. increasing absorption of calcium and phosphate from intestines
  2. increasing reabsorption of calcium and phosphate from kidneys
  3. increasing reabsorption of calcium and phosphate from bone
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21
Q

what is the result of abnormal bone mineralization in children with rickets

A
  1. pigeon breasted deformity- inward bending ribs with anterior protrusion o the sternum
  2. frontal bossing (enlargement of the forehead- due to osteiod deposition on the skull
  3. rachitic rosary- due to osteoid deposition in the costochondral junction
  4. bowing of the legs
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22
Q

what are lab finding of osteopetrosis

A

decreased serum calclium, decreased serum phosphate, increase PTH and increased alk phos.

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23
Q

Osteoporosis is due to a decrease in _______ bone mass

A

trabecular

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24
Q

risk of Osteoporosis is based on peak bone mass. what 3 factors determine peak bone mass

A
  1. diet
  2. Exercise
  3. vitamin D receptor
    it is achieved by age 30
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25
Q

rate of bone loss is determined by

A
  1. diet
  2. exercise
  3. estrogen, which serves to protect bones
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26
Q

what are lab finding with osteomalacia

A

decreased serum calcium
decreased serum phosphate
increased PTH
increased alkaline phosphatase

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27
Q

why is there an increased alkaline phosphatase with osteomalacia?

A

if there are active osteoblasts, there will be increased alkaline phosphatase because a basic/ alkaline environment is needed to deposit calcium. osteoblasts are active with osteomalacia

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28
Q

what do osteoblasts due and how does this impact osteomalacia and rickets

A

osteoblasts lay down osteoid, which is then is converted to bone with calcium and phosphate mineralization. with osteomalation and rickets, there is osteoid deposition, but defective mineralization

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29
Q

what are the clinical features of Osteoporosis

A
  1. bone pain and fractures in weight bearing areas such as vertebrae, hip, and distal radius
  2. bone density decrease, which is measured by DEXA scan
  3. serum calcium, phosphate, PTH, and alkaline phosphatase are normal, which helps to differentiate from osteomalacia
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30
Q

how do lab tests differ with osteomalacia and osteoporosis

A

with Osteoporosis, serum calcium, phosphate, PTH, and alkaline phosphatase are normal.

with osteomalacia, serum calcium and phosphate are decreased, and PTH and alkaline phosphatase are elevated

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31
Q

what are the treatments for osteoporosis

A
  1. exercise, vitamin D, and calcium to limit bone loss
  2. bisphosphonates, which induce apoptosis of osteoclasts.
  3. estrogen replacement therapy is debated
  4. glucocorticoids are contraindicated
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32
Q

Paget’s disease of bone is caused by an imbalance between…

A

osteoblast and osteoclast function

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33
Q

Paget’s disease is a _______ process that involves _______ bones.

A

localized process that involves one or more bones, not the entire skeleton

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34
Q

what are the three phases of Paget’s disease

A
  1. osteoclastic: osteoclasts go crazy
  2. mixed osteoblastic-osteoclastic: osteoblasts also kick in to try and help
  3. osteoblastic: osteoclasts burn out and osteoblasts continue, which results in thick, sclerotic bone that fractures easy.
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35
Q

what is the relationship between osteoclasts and osteoblasts

A

osteoblasts manage osteoclasts. osteoblasts have the PTH receptor, so osteoclasts shouldn’t work without being told to by osteoblasts, which receive PTH

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36
Q

what will biopsy reveal with Paget’s disease

A

mosaic pattern of lamellar bone that looks like puzzle pieces

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37
Q

what are the clinical features of Paget’s disease

A
  1. bone pain due to microfractures
  2. increasing HAT SIZE due to skull being affected
  3. hearing loss due to impingment of cranial nerves
  4. LION LIKE FACIES due to involvment of cranial facial bones
  5. isolated elevated ALK PHOS.
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38
Q

Paget’s disease is the most common cause of isolated elevated ________ in patients over 40

A

alkaline phosphatase

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39
Q

treatment of Paget’s disease of bone includes

A

calcitonin to inhibit osteoclast function

bisphosphonates to induce apoptosis of osteoclasts

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40
Q

what are two complications of Paget’s disease (HIGH YIELD)

A
  1. HIGH OUTPUT CARDIAC FAILURE DUE TO FORMATION OF AV SHUNTS

2. OSTEOSARCOMA

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41
Q

osteomyelitis is an infection of the ______ and ______ that usually arises in ________ and is most commonly caused by ____

A

bone and marrow, children, bacteria

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42
Q

osteomyelitis is usually caused by bacteria through ________ spread. it typically seeds in which areas for children and adults?

A

hematogenous spread. transient bacteremia in children seeds in the METAPHYSIS. open round bacteremia in adults seeds in the EPIPHYSIS. HIGH YIELD

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43
Q

bacterial causes of osteomyelitis include (6)

A
  1. S. aureus: most common, 90%
  2. N gonorrhoeae: sexually active young adults
  3. Salmonella: most common with sickle cell
  4. Pseudomonas: diabetics and IV drug users
  5. Pasteurella: cat or dog bites or scratches
  6. Mycobacterium Tuberculosis: usually involves vertebrae
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44
Q

clinical features of osteomyelitis

A
  1. bone pain with systemic findings like fever and leukocytosis
  2. Lytic focus (abscess) surrounded by SCLEROSIS of bone of X ray.
    - - lytic focus is called SEQUESTRUM
    - - sclerosis is called INVOLCRUM
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45
Q

diagnosis of osteomyelitis is made by _______

A

blood culture

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46
Q

avascular (aseptic) necrosis is

A

ischemic necrosis of the bone and bone marrow

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47
Q

what are the causes of avascular necrosis, as well as the complications

A

trauma of fracture (most common). steroids, sickle cell anemia (dactylitis), and caisson disease (nitrogen emboli).

complications include osteoarthritis and fractures

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48
Q

Osteoma is a ______ tumor of bone

A

benign (oma)

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49
Q

osteoma most commonly arises on the _________ and is associated with ________ syndrome

A

surface of facial bones; Gardner Syndrome

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50
Q

Osteoid osteoma is a _______ tumor of ______ surrounded by a rim of ________

A

benign tumor of osteoblasts (that produce osteoid) surrounded by a rim of reactive bone.

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51
Q

Osteoid osteoma arises in the ________ and occurs in what age?

A

CORTEX of long bones and occurs at age <25, more commonly in males

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52
Q

Osteoid osteoma presents as….

A

bone pain that RESOLVES WITH ASPIRIN

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53
Q

What are the three main differences between Osteoid osteoma and osteoblastoma

A
  1. osteoblastoma has a bone mass >2 cm, which Osteoid osteoma is <2cm
  2. osteoblastoma arises in the vertebrae, while Osteoid osteoma is in the cortex of long bones
  3. osteoblastome arises as bone pain that DOES NOT RESOLVE WITH ASPIRIN
54
Q

Osteochondroma is ….

A

tumor of bone with an overlying cartilage cap. it is the MOST COMMON BENIGN TUMOR OF BONE

55
Q

Osteochondroma arises from a _______ of the growth plate (metaphysis) and the bone is _______ with the marrow space

A

lateral projection of metaphysis and is continuous with the marrow space

56
Q

a complication of osteochondroma is….

A

the overlying cartilage can transform into chondrosarcoma

57
Q

Osteosarcoma is a …

A

malignant proliferation of osteoblasts. MALIGNANT = SARCOMA

58
Q

Peak incidence of osteosarcoma is seen in _____ and _______

A

teens and elderly

59
Q

what are the risk factors for osteosarcoma (3)

A
  1. familial retinoblastoma (Teens)
  2. Paget disease (elderly)
  3. radiation exposure (elderly)
60
Q

where does osteosarcoma typically present

A

arises in the metaphysis of long bones, usually the distal femur and proximal tibia (region of the knee) HIGH YIELD

61
Q

how does osteosarcoma present

A

as a pathological fracture or bone pain with swelling

62
Q

what does imaging of osteosarcoma reveal

A

destructive mass with “sun burst” appearance and lifting of the periosteum, which is called CODMAN’S TRIANGLE/ ANGLE

63
Q

biopsy of osteosarcoma reveals

A

pleomorphic cells that produce osteoid. this is the hallmark biopsy

64
Q

Giant cell tumor is the only relevant tumor occurring in the

A

epiphysis. typically occurs in young adults in the epiphysis

65
Q

why can giant cell tumor and osteosarcoma have a similar presentation

A

because they both occur in the distal femur or proximal tibia (region of the knee)

66
Q

what is the x ray appearance of Giant Cell Tumor

A

“soap bubbles” in the epiphysis

67
Q

Ewing sarcoma is a _______ proliferation of poorly differentiated cells derived from _______

A

malignant, neuroectoderm

68
Q

where does Ewing sarcoma arise

A

in the diaphysis of the long bones, usually in male children less than 15 years of age

69
Q

and “onion skin” appearance on x ray is indicative of…

A

Ewing sarcoma

70
Q

what mutation is characteristic of Ewing sarcoma

A

translocation 11;22

71
Q

biopsy of Ewing sarcoma reveals

A

small, round blue cells that resemble lymphocytes. can be confused with lymphoma or chronic osteomyelitis

72
Q

chondrosarcoma is a ________, ________ forming tumor that arises in ________

A

malignant cartilage forming tumor that arises in medulla of pelvis or central skeleton

73
Q

chondroma is a _____ tumor of ______ that arises in _______

A

benign tumor of cartilage that arises in medulla of small bones of hands and feet

74
Q

what are the three main points of cartilage tumors

A
  1. both commonly arise in the medulla
  2. benign tumors occur in small bones of hands and feet (chondroma)
  3. malignant tumors arise in pelvis or central skeleton (chondrosarcoma)
75
Q

metastatic bone tumors usually results in ______ lesions. what is the main exception

A

punch out lesions. prostatic carcinoma classically produces osteoblastic lesions (sclerosis of bone)

76
Q

degenerative joint disease (osteoarthritis) is most often due to ______. how common is it?

A

wear and tear. most common form of arthritis.

77
Q

what are the three main risk factors for degenerative joint disease (osteoarthritis)

A

age, obesity, trauma

78
Q

what is the classical presentation of degenerative joint disease (osteoarthritis)

A

joint stiffness in the mornings that worsens throughout the day HIGH YIELD

79
Q

does degenerative joint disease (osteoarthritis) include the DIP, PIP, or both

A

both

80
Q

what are the pathologic features of degenerative joint disease (osteoarthritis) (3)

A
  1. disruption of the cartilage that lines the articular surfaces, with fragments of cartilage floating in joint space (joint mice)
  2. eburnation/ polishing of the subchondral bone
  3. osteophyte formation (reactive bony outgrowths)
81
Q

with degenerative joint disease (osteoarthritis), what are the names of osteophytes in the DIP and PIP

A

DIP: HEBERDEN NODES
PIP: BOUCHARD NODES

82
Q

Rheumatoid Arthritis is a ___________ disease

A

chronic, systemic autoimmune disease

83
Q

Rheumatoid Arthritis is assocaited with….

A

HLA-DR4

84
Q

Rheumatoid Arthritis is characterized by involvement of joints. what is the hallmark joint involvement

A

synovitis leading to formation of pannus (inflamed granulation tissue). the contraction of the granulation tissue leads to destruction of cartilage and ankylosis (fusion) of the joint

85
Q

what are the 6 clinical features of Rheumatoid Arthritis

A
  1. symmetric involvement of PIP joints of fingers (Swan neck deformity), wrists (radial deviation), elbows, ankles, and knees. DIP spared
  2. fevers, malaise, weight loss, and myalgias
  3. rheumatoid nodules (central zone of necrosis surrounded by epithelial histiocytes)
  4. vasculitis
  5. baker cyst: swelling of bursa behind the knee
  6. pleural effusions, lymphadenopathy, and interstitial lung fibrosis
86
Q

what are the lab findings with Rheumatoid Arthritis

A

IgM autoantibody against the Fc portion of IgG (rheumatoid factor); marker of tissue damage and disease activity.

neutrophils and high protein in the synovial fluid

87
Q

what are two complications of Rheumatoid Arthritis

A

anemia of chronic disease and secondary amyloidosis

88
Q

seronegative spondyloarthropathies are a group of joint disorders characterized by (3)

A
  1. lach of rheumatoid factors (seronegative)
  2. axial skeleton involvement (spondylo)
  3. HLA-B27 associated
89
Q

seronegative spondyloarthropathies include which three conditions

A
  1. ankylosing spondyloarthritis
  2. reiter syndrome
  3. psoriatic arthritis
90
Q

Ankylosing Spondyloarthritis involves ______ and ______.

A

sacroiliac joints and spine

91
Q

Ankylosing Spondyloarthritis presentation

A

arises in oung adults, most often males

presents with low back pain, involvement of the vertebral bodies can eventually arise, leading to fusion of the vertebrae (bamboo spine)

extra articular manifestations include uveitis and aortitis, leading to aortic regurgitation

92
Q

Reiter Syndrome is characterized by what triad and what is the presentation

A

Arthritis, urethritis, and conjuctivitis. “cant pee, can’t see, cant climb a tree.”

arises in young adults, typically males, weeks after a GI or chlamydia infection

93
Q

psoriatic arthritis is seen in ____ of psoriasis cases and presents…

A

involves the axial and peripheral joints. DIP joints of the hands and feet are the most commonly effected, leading to SAUSAGE FINGERS AND TOES.

94
Q

Infectious arthritis is typically due to bacterial infections, most commonly which two etiologies

A

N. Gonorrhoeae with young adults

S aureus with older children and adults

95
Q

infectious arthritis typically involves how many joints and what is the presentation?

A

single joint, usually the knee. presents as a warm joint with imited ROM, fevers, increased white count, and elevated ESR are common.

96
Q

Gout is due to deposit of ______ in tissues, especially joints, with is a result of _______

A

monosodium urate (MSU); hyperuricemia (related to overproduction or decreased production of uric acid

97
Q

uric acid is derived from….

A

purine metabolism. it is excreted by the kidneys

98
Q

primary gout is how common? what is the etiology of the hyperuricemia?

A

the most common form of gout. etiology unknown

99
Q

secondary gout is seen with which three conditions

A
  1. leukemia and myeloproliferative disorders
  2. Lesch-Nyhan syndrome
  3. renal insufficiency
100
Q

how does leukemia and myeloproliferative disorders lead to secondary gout?

A

increased cell turnover leads to hyperuricemia

101
Q

how does Lesch-Nyhan Syndrome lead to secondary gout? what does this condition present like?

A

x linked deficiency of HYPOXANTHINE-GUANINS PHOSPHORIBOSYLTRANFERASE (HGPRT), which typically salvages xanthine and guanine. lack of this leads to increased production of uric acid. presents with mental retardation and self mutilation.

102
Q

how does renal insufficiency lead to secondary gout?

A

decreased excretion of uric acid

103
Q

How does acute gout present and what is a brief explanation of the pathophysiology? what two conditions may precipitate arthritis?

A

presents as exquisitely painful arthritis of the great toe (podagra). it is due to MSU crystals depositing in the joint, triggering and acute inflammatory reaction. alcohol or consumption of meat may precipitate arthritis.

104
Q

what two conditions does chronic gout lead to?

A

development of TOPHI (white chalky aggregates of uric acid crystals with fibrosis and giant cell reactions in the soft tissues and joints)

renal failure - urate crystals may deposit in kidney tubules.

105
Q

what are the lab findings with gout

A

hyperuricemia. synovial fluid shows NEEDLE SHAPED CRYSTALS WITH NEGATIVE BIFRINGENCE upon polarized light. HIGH YIELD

106
Q

pseudogout resembles gout clinically, but is due to _______

A

calcium pyrophosphate dihydrate (CPPD). synovial fluid will show RHOMBOID SHAPED CRYSTALS WITH WEAKLY POSITIVE BIFRINGENCE, while gout will show NEEDLE SHAPED CRYSTALS WITH NEGATIVE BIFRINGENCE

107
Q

what is a lipoma

A

benign tumor of adipose tissue. MOST COMMON BENIGN SOFT TISSUE TUMOR IN ADULTS

108
Q

what is liposarcoma and what is the characteristic cell?

A

malignant tumor of adipose tissue. MOST COMMON MALIGNANT SOFT TISSUE TUMOR IN ADULTS. LIPOBLAST is the characteristic cell

109
Q

what is rhabdomyoma?

A

benign tumor of skeletal muscle.

110
Q

cardiac rhabdomyoma is associated with…

A

tuberous sclerosis

111
Q

what is rhabdomyosarcoma

A

malignant tumor of skeletal muscle and the MOST COMMON MALIGNANT SOFT TISSUE TUMOR IN CHILDREN

112
Q

what is the characteristic cell of rhabdomyosarcoma

A

rhabdomyoblast, which is DESMIN POSITIVE

113
Q

what are the most common sites of rhabdomyosarcoma

A

head and neck; vagina is classic site in young girls (known as Sarcoma Botryoides Variant)

114
Q

dermatomyositis is an inflammatory disorder of the ______ and ______. it has an unknown etiology, byt some cases are associated with ________

A

skin and skeletal muscle. carcinoma, especially gastric carcinoma.

115
Q

what are the clinical features of dermatomyositis?

A
  1. bilateral PROXIMAL MUSCLE WEAKNESS (HALLMARK) with potential distal involvement late in the disease.
  2. rash of the UPPER EYELIDS (HELITROPE RASH), with potential MALAR RASH (must differentiate from lupus)
  3. RED PAPULES on elbows, knuckles, and knees (GOTTRAN PAPULES)
116
Q

what are the laboratory findings with dermatomyositis?

A
  1. increased creatine kinase
  2. POSITIVE ANA AND ANTI JO-1 ANTIBODY (HALLMARK)
  3. perimysial inflammation (CD4+ T cells) with perifasicular atrophy on biopsy (HIGH YIELD)
117
Q

what is the treatment for dermatomyositis?

A

corticosteroids.

118
Q

what is polymyositis? what does it resemble?

A

inflammatory disorder of skeletal muscle. resembles dermatomyositis clinically, but SKIN IS NOT INVOLVED.

119
Q

how do dermatomyositis and polymyositis differ on biopsy?

A

dermatomyositis: PERImysial inflammation (CD4+ T cells) with perifasicular atrophy on biopsy (HIGH YIELD)
polymyositis: ENDOmysial inflammation (CD8+ T cells) with necrotic muscle fibers seen on biopsy

120
Q

X linked muscular dystrophy (Duchenne) is…

A

degenerative disorder characterized by muscle wasting and REPLACEMENT OF SKELETAL MUSCLE BY ADIPOSE TISSUE (HIGH YIELD)

121
Q

X linked muscular dystrophy is due to defects in what gene? what is the role of the protein formed by this gene?

A

dystrophin gene. dystrophin is important in anchoring muscle to cytoskeleton extracellular matrix. mutations are often spontaneous and the large gene predisposes it to a high rate of mutation

122
Q

how does dystrophin vary with X linked muscle dystrophy and duchenne

A

with duchenne, the dystrophy is due to the deletion of the dystrophin gene

with x linked, the dystrophy is due to defects in the dystrophin gene

123
Q

how does duchenne muscular dystrophy present?

A

presents as proximal muscle weakness at 1 year of age, which progresses to involve the distal muscles

124
Q

What is the characteristic finding of Duchenne muscular dystrophy

A

calf pseudohypertrophy. will have an elevated CK

125
Q

what is the cause of Becker Muscular dystrophy

A

mutated dystrophin that results in more mild disease

126
Q

what is the cause of myasthenia gravis

A

autoantibodies against the post synaptic ACETYLCHOLINE RECEPTOR and the neuromuscular junction

127
Q

what are the clinical feature of myasthenia gravis?

A
  1. muscle weakness that WORSENS with use and improves with rest, classically involving eyes, leading to ptosis and diplopia.
  2. symptoms improve with anticholinesterase agents
128
Q

myasthenia gravis is associated with what?

A

thymic hyperplasia and thymoma. thymectomy improves symptoms

129
Q

what is the cause of Lambert-Eaton Syndrome?

A

antibodies against the presynaptic calcium channels of the neuromuscular junction. arises as a paraneoplastic syndrome, most commonly due to small cell carcinoma of the lung. leads to IMPAIRED ACETYCHOLINE RELEASE, as firing of the presynaptic calicium channels is required for release

130
Q

what are the clinical features of Lambert-Eaton Syndrome?

A
  1. proximal muscle weakness that IMPROVES WITH USE, EYES ARE USUALLY SPARED
  2. Anticholinesterase agents do not improve symptoms
  3. resolves with resection of cancer
131
Q

what are the clinical differences between myasthenia gravis and lambert-eaton syndrome?

A
  1. both involve muscle weakness, but myasthenia gravis is WORSE with use. Lambert- Eaton is improved with use
  2. anticholinesterase agents improve Myasthenia Gravis, but have no impact on Lambert- Eaton
132
Q

how does the involvement of the neuromuscular junction with Myasthenia Gravis and Lambert-Eaton syndrome differ?

A

myasthenia gravis: antibodies againts the POST SYNAPTIC acetylcholine receptor. ACH is in cleft, which is why antichoinesterase agents work

Lambert-Eaton: antibodies against the PRE SYNAPTIC calcium channels, which prevents release of ACH into the synaptic cleft. this is why anticholinesterase agents do not work.

Pathoma (6 decks)

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