Bone, Joint & Muscle Pathology Flashcards

1
Q

What is Achondroplasia?

A
  • Failure of longitudinal bone growth (endochonrdal ossification)→ short limbs
  • Membranous ossification is not affected→ large head & chest relative to limbs
  • Common cause of dwarfism
  • Normal life span & fertility
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2
Q

**Growth Factor involved in Achondroplaisa **

A

Constitutive activation of fibroblast GF receptor (FGFR3) acutally inhibits chondrocyte proliferation

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3
Q

Pattern of Inheritance of Achondroplaisa

A
  • AD inheritance
  • 85% occur sporadically & assoc w/ advanced paternal age
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4
Q

What is Osteoporosis?

A

Trabecular (spongy) bone loses mass & interconnections despite normal bone mineralization & lab values ( serum Ca2+ & PO43-)

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5
Q

What is Type I Osteoporosis?

A
  • Postmenopausal: inc bone resportion d/t dec estrogen levels
  • Femoral neck fracture, distal radius (Colles’) fractures
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6
Q

What is Type II Osteoporosis?

A
  • Senile osteoporosis
  • Affects men & women >70 years of age
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7
Q

Prophylaxis for Type II Osteoporosis

A
  • Regular wt bearing exercise
  • Sdequate Ca & Vit D intake throughout adulthood
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8
Q

Tx for Osteoporosis Type II

A
  • Estrogen (SERMs) &/or calcitonin
  • Bisphosphonates (induce osteoclast apoptosis)
  • Pulsatile PTH for severe cases
  • Glucocorticoids are contraindicated
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9
Q

What is Osteopetrosis?

A

Failure of normal bone resorption d/t defective osteoclasts→ thickened, dense bones that are prone to fracture

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10
Q

What does Osteopetrosis look like?

A

Bone fills marrow space, causing pancytopenia, extramedullary hematopoiesis

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11
Q

What mutations are involved w/ Osteopetrosis?

A

Carbonic anyhydrase II→ loss of the acidic microenvironment required for bone resorption

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12
Q

Look of Osteopetrosis on X-ray

A

Bone-in-bone appearance

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13
Q

What are the clinical features of Osteopetrosis?

A
  • Bone fractures
  • Anemia, thrombocytopenia & leukopenia w/ extramedullar hematopoiesis
  • Hydrocephalus d/t narrowing of foramen magneum
  • Renal tubular acidosis
  • Cranial nerve impingement→ vision & hearing impairment
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14
Q

Tx for Osteopetrosis

A

BM transplant is potentialy curative as osteoclasts are derived from monocytes

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15
Q

What can Vit D deficiency cause?

A
  • Rickets in children
  • Osteomalacia in adults
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16
Q

Pathway of Vit D Deficiency

A
  • dec Vit D→ dec serum Ca→ Inc PTH secretion → dec serum phosphate
  • Hyperactivity of osteoclasts→ inc alk phos
  • Defective mineralization/ calcification of osteoid→ soft bones that bow out
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17
Q

What is Paget dz of bone (Osteitis deformans)?

A

Common, localized disorder of bone remodeling caused by an imbalance in osteoblastic & osteoclastic activity

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18
Q

Lab Values of Osteitis deformans

A

Normal serum Ca, P & PTH levels w/ inc ALP

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19
Q

What does osteitis deformans look like?

A
  • Mosaic (“woven”) bone pattern
  • Long bone chalk-stick fractures
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20
Q

What can Osteitis deformans cause?

A
  • Inc blood flow from inc arteriovenous shunts may cause high-output HF
  • Inc risk of osteosarcoma
  • Hat size can be Inc
  • Hearing loss is common d/t auditory foramen narrowing
  • Bone pain
  • Lion-like face
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21
Q

What is osteitis fibrosa cystica?

A
  • “Brown tumors” of hyperparathyroidism
  • Inc serum Ca, ALP, PTH & dec P
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22
Q

What is Polyostotic fibrous dysplasia?

A

Bone replaced by fibroblasts, collagen & irregular bony trabeculae

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23
Q

What is McCune-Albright Syndrome?

A

Form of polycystic fibrous dysplasia char by mulitple unilateral bone lesions assoc w/ endocrine ABN (precocious puberty) & café-au-lait spots

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24
Q

What are the 1º benign bone tumors?

A
  • Giant cell tumor (osteoclastoma)
  • Osteochondroma (exostosis)
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25
Q

What age group osteoclastoma occur?

A

20-40yo

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26
Q

What is Giant Cell tumor?

A

Locally aggressive benign tumor that arises in the epiphysis of long bones, us. the distal femur or proximal tibial region (knee)

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27
Q

What is the appearance of Giant Cell tumor on X-ray?

A

“Double bubble” or “soap bubble”

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28
Q

Histo of Giant cell tumor

A

Spindle-shaped cells w/ multinucleated giant cells & stromal cells

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29
Q

Who does Osteochonroma occur in?

A

Males <25yo

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30
Q

What is Osteochondroma?

A
  • Most common benign tumor
  • Mature bone w/ cartilagenous cap
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31
Q

Where does Osteochondroma commonly originate?

A

Arise from a lateral projection of the growth plate (metaphysis); bone is continous w/ marrow space

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32
Q

What does Osteochondroma transform to?

A

Rare transformation to chondrosarcoma

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33
Q

What are the 1° malignant bone tumors?

A
  • Osteosarcoma (osteogenic sarcoma)
  • Ewing’s sacroma
  • Chondrosarcoma
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34
Q

Who gets Osteosacroma?

A
  • Males> females
  • 10-20 yo
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35
Q

What are the predisposing factors to Osteosarcoma?

A
  • Paget’s dz of bone
  • Bone infarcts
  • Radiation
  • Familial retinoblastoma
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36
Q

Characteristics of Osteosarcoma

A
  • Metaphysis of long bones, often around distal femur, proximal tibial region (knee)
  • Codman’s triangle (from elevation of periosteum or ‘sunburst pattern’ on X-ray
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37
Q

Tx of Osteosarcoma

A

Aggressive, tx w/ surgical en bloc resection (w/ limb salvage) & chemotherapy

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38
Q

Who gets Ewing’s Sarcoma?

A

Boys <15yo

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39
Q

Where does Ewing’s Sarcoma occur?

A

Commonly appears in diaphysis of long bones, pelvis, scapula & ribs

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40
Q

Histo of Ewing’s Sarcoma

A
  • Anaplastic small blue cells that resemble lymphocytes
  • “Onion skin” appearance on X-ray
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41
Q

Prognosis of Ewing’s Sarcoma

A

Extremely aggressive w/ early mets but responsive to chemo

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42
Q

What translocation is Ewing’s Sacroma assoc w/?

A

t(11;22) translocation

(11+22=33 Patrick Ewing’s jersey #)

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43
Q

Who gets Chonrosarcoma?

A

Men 30-60yo

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44
Q

Where is Chondrosarcoma located?

A

Pelvis, spine, scapula, humerus, tibia or femur

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45
Q

What is Chondrosarcoma?

A
  • Malignant cartilaginous tumor
  • May be of 1° origin or from osteochondroma
  • Expansile glistening mass w/in the medullary cavity
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46
Q

Cause of Osteoarthritis

A

Mechanical- joint wear & tear destroys articular cartilage

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47
Q

Joint findings of Osteoarthritis

A
  • Subchondral cysts
  • Sclerosis
  • Osteophytes (bone spurs)
  • Eburnation (polished ivory-like appearance of bone)
  • Bouchard’s nodes (PIP)
  • Heberden nodes (DIP)
  • No MCP involvement
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48
Q

Predisposing factors of Osteoarthritis

A
  • Age (>60yo) major RF
  • Obesity
  • Joint deformity
  • Trauma
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49
Q

Clinical Presentation of Osteoarthritis

A
  • Joint stiffness in the morning that worsens during the day & improves w/ rest
  • Knee CT loss begins medially (“bowlegged”)
  • Noninflammatory
  • No systemic sx
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50
Q

Tx of Osteoarthritis

A

NSAIDs & Intra-articular glucocorticoids

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51
Q

Cause of Rheumatoid arthritis

A
  • Autoimmune- inflammatory destruction of synovial joints
  • Type III hypersensitivity
  • IgM auto-Ab against Fc portion of IgG (rheumatoid factor)
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52
Q

Joint findings in RA

A
  • Synovitius→ Pannus (inflam granulation tissue)
  • Rheumatoid nodules: central zone of necrosis surrounded by epi histiocytes
  • Radial deviation of wrists
  • Ulnar deviation of fingers
  • Boutonniere deformity of thumb
  • Baker’s cysts (in politeal fossa)
  • No DIP involvement*
  • Swan-neck deformity of fingers
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53
Q

Predisposing Factors of RA

A
  • Classically women of childbearing age
  • 80% have + Rheumatoid factors (anti-IgG Ab)
  • Anti-cyclic citrullinated peptide Ab is more specific
  • Strong assoc w/ HLA-DR4**
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54
Q

Clinical Presentation of RA

A
  • Morning stiffness lasting >30 min & improving w/ use
  • Symmetric joint involvement
  • Systemic sx- fever, fatigue, pleuritis, pericarditis, vasculitis, lymphadenopathy, interstitial lung fibrosis
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55
Q

Tx of RA

A
  • NSAIDs
  • Glucocorticoids
  • Dz-modifying agents (methotrexate, sulfasalazine, TNF-alpha inhibitors)
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56
Q

What is Sjögren’s Syndrome?

A

Lymphocytic infiltration of exocrine glands, especially lacrimal & salivary

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57
Q

Classic Triad of Sjögren’s Syndrome

A
  • Xerophthalamia- dry eyes, conjuctivitis, “sand in my eyes”
  • Xerostomia- dry mouth, dysphagia
  • Arthritis
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58
Q

Characteristics of Sjögren’s Syndrome

A
  • Parotid enlargement
  • inc risk of B-cell lymphoma
  • Dental Caries
  • Auto-Ab to ribonucleoprotein Ag: SS-A (Ro), SS-B (La)
  • Assoc w/ rehumatoid arthritis
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59
Q

What is Gout?

A

Precipitation of monosodium urate crystals into joints d/t hyperuricemia from overy production or dec excretion of uric acid

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60
Q

What does Gout look like?

A

Crystals are needle shaped & negatively birefringemant= yellow crystals under parallel light

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61
Q

Sx of Gout

A
  • Asymmetric joint distribution
  • Joint is swollen, red & painful
  • Classic manifestation is painful MTP joint of the big toe (podagra)
  • Tophus formation (often on external ear, olecranon bursa or Achilles tendon)
  • Acute attack tends to occur after a large meal or alcohol consumption (alcohol metabolites compete for same excretion sites in kindney as uric acid, causing dec uric acid sec & subsequent bulidup in blood)
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62
Q

Tx of Gout

A
  • Acute: NSAIDs (indomethacin), glucocorticoids
  • Chronic: xanthine oxidase inhibitors (allopurinol, febuxostat)
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63
Q

Cause of Pseudogout

A
  • Depostions of Ca pyrophosphate dihydrate (CPPD) crystals w/in the joint space
  • Usuallly affects large joints (classically the knee)
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64
Q

What does Pseudogout look like?

A
  • Forms basophilic, rhomoid crystals that are weakly + birefringement
  • Crystals are blue when parallel to the light
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65
Q

Who gets Pseudogout?

A
  • >50yo
  • Effects both sexes equally
66
Q

Tx of Pseudogout

A
  • NSAIDs for sudden severe attacks
  • Steroids
  • Colchicine
67
Q

Causes of Infectious Arthritis

A
  • S. aureus
  • Streptococcus
  • Niesseria gonorrheaoeae
68
Q

What is Infectious Arthritis?

A
  • Arthritis d/t an infectious agent
  • Gonococcal arthritis is an STD that presents as a migratory arthritis w/ an asymmetric pattern
69
Q

Sx of Infectious Arthritis

A
  • Affected joint is swollen, red & painful
  • Synovitis (knee)
  • Tenosynovitis (hand)
  • Dermatitis (pustules)
  • Fever, Inc WBC & inc ESR
70
Q

What is Osteonecrosis?

A
  • Avascular necrosis
  • Infarction of bone & marrow
  • Pain assoc w/ activity
  • MC site is femoral head
71
Q

Causes of Osteonecrosis

A
  • Trauma
  • High-dose corticosteroids
  • Alcoholism
  • Sickle cell
72
Q

What are Seronegative spondyloarthropathies?

A
  • Arthritis w/o rheumatoids factor (no IgG Ab)
  • Psoriatic arthritis
  • Ankylosing spondylitis
  • IBS
  • Reactive arthritis (Reiter’s synd)
73
Q

What seronegative spondyloarthropathies asoc w/?

A
  • HLA-B27 (gene that codes for HLA- MHC class I)
  • Occurs more often in males
  • Axial skeleton involvement
  • Lack of rheumatoid factor
74
Q

What is Psoriatic arthritis?

A
  • Joint pain & stiffness seen in hands & feet
  • Asymmetric & patchy involvement
  • Dactylitis “sausage fingers”
  • Pencil-in-cup deformity on X-ray
75
Q

What is Ankylosing spondylitis?

A
  • Chronic inflam dz of spine & sacroiliac joints→ ankylosis
  • Bamboo spine (vertebral fusion)
  • Uveitis & aoritic regurg
76
Q

What is IBS?

A

Chron’s dz & UC are often accompanied by ankylosing spondylitis or peripheral arthritis

77
Q

Reactive arthritis (Reiter’s Synd) Triad

A
  • Conjunctivitis & anterior uveitis
  • Urethritis
  • Arthritis
  • “Can’t see, can’t pee, can’t climb a tree”
  • Post GI or chlamydia infections
78
Q

Who gets SLE?

A
  • 90% are female
  • 14-45yo
  • MC & severe in black females
79
Q

Clinical presentation of SLE

A
  • Fever, fatigue, wt loss
  • Libman-sacks endocarditis (verrucous war-likem sterile vegetations on both sides of valve)
  • Hilar adenopathy
  • Raynaoud’s phenomenon
80
Q

What is the common COD in SLE?

A

Nephritis→ Diffuse proliferative glomerulonephritis

81
Q

What causes false + on the syphillis test (RPR/VDRL)?

A

Antiphospolipid Ab’s which cross-react w/ cardiolipin used in tests

82
Q

What do SLE lab tests detect?

A
  • Antinuclear Ab’s (ANA)- sensitive, (1° screening) but not specific for SLE
  • Ab’s to ds-DNA (anti-dsDSA)- very specific, poor prognosis,
  • Anti-Smith Ab’s (anti-Sm)- very specific, but not prognostic
  • Antihistone Ab’s- more sensitive for drug-induced lupus
83
Q

I’M DAMN SHARP

(SLE characteristics)

A
  • Ig’s (anti-dsDNA, anti-Sm, antiphospholipid)
  • Malar rash
  • Discoid rash
  • Antinuclear Ab
  • Mucositis (oropharyngeal ulcers)
  • Neurologic disorders
  • Serositis (pleuritis, pericarditis)
  • Hematologic disorders
  • Arthritis
  • Renal disorders
  • Photosensitivity
84
Q

Characteristics of Sacroidosis

A
  • Immune-mediated, widesspread noncaseating granulomas & elevated serum ACE levels
  • Often asx except for enlarged LN
  • Common in black females
85
Q

What is Sarcoidosis assoc w/?

A
  • Restrictive lung dz (interstitial fibrosis)
  • Erythema nodosum
  • Bell’s palsy
  • Epi granulomas containing microscopic Schaumann & asteroid bodies
  • Uveitis
  • Hyper-Ca (d/t elevated 1-alpha-med vit D activation in epitheloid macro)
86
Q

Tx of Sarcoidosis

A

Steroids

87
Q

Sx of Polymyalgia rheumatica

A
  • Pain & stiffness in shoulds & hips
  • Fever
  • Malaise
  • Wt loss
  • Does not cause muscle weakness
88
Q

Who gets Polymyalgia rheumatica?

A

MC in women >50yo

89
Q

What is associated with Polymyalgia rheumatica?

A

Temporal (giant cell) arteritis

90
Q

Findings in Polymyalgia rheumatica

A

Inc ESR & normal CK

91
Q

Tx of Polymyalgia rheumatica

A

Rapid response to low-dose corticosteroids

92
Q

Who gets Fibromyalgia?

A

MC seen in women 20-50yo

93
Q

What is Fibromyalgia?

A

Chronic, widespread MSS pain assoc w/ stiffness, paresthesia, poor sleep & fatigue

94
Q

What is Polymyositis?

A
  • Progressive symmetric proximal muscle weakness
  • Char by endomysial inflam w/ CD8+ T cells w/ necrotic muscle fibers
  • Most often involves shoulders but NOT skin
95
Q

What are the characteristics of Dermatomyositis?

A
  • Similar to polymyositis except it involves the skin
  • Bilateral proximal muscle weakness
  • Malar rash (similar to SLE)
  • Gottron’s lesions→ red papules on elbows, knuckles & knees
  • Heliotrope rash (upper eyelids)
  • “Mechanic hands”
96
Q

What is found on muscle biopys in dermatomyositis?

A

Perimysial inflam (CD4+ T cells) w/ perifasciular atrophy on bx

97
Q

What does Dermatomyositis inc the risk of?

A

Occult Malignancy

98
Q

Lab findings in Polymyositis/Dermatomyositis

A
  • Inc creatine kinase
    • ANA
    • anti-Jo-1 Ab’s***
99
Q

Tx of Polymyositis/dermatomyositis

A

Corticosteroids

100
Q

What is the freq of Myasthenia gravis?

A

MC NMJ disorder

MC in women

101
Q

What is the cause of Myasthenia gravis?

A

Auto-Ab’s to postsynaptic ACh receptors at NMJ

102
Q

What does AChE inhibitor admin do in Myasthenia gravis?

A

Reversal of sx

103
Q

Clinical characterisitics of Myastenia gravis

A
  • Ptosis
  • Diplopia
  • Weakness
  • Worsens w/ muscle use
104
Q

What is Myasthenia gravis assoc w/?

A

Thymoma & thymic hyperplasia→ thyectomy improves sx

105
Q

Freq of Lmabert-Eaton myasthenic synd

A

Uncommon

106
Q

Cause of Lamber-Eaton myasthenic synd

A

Auto-Ab’s to presynaptic Ca2+ channel at NMJ→ dec ACh release

107
Q

Clinical sx of Lamber-Eaton Synd

A

Proximal muscle weakness that improves w/ muscle use. Eyes are spared

108
Q

What is Lamber-Eaton synd assoc w/?

A

Small cell lung cancer→ paraneoplastic synd

109
Q

What does AChE inhibitor admin in Lamber-Eaton Synd do?

A

No effect

110
Q

What is Myositis ossificans?

A

Metaplasia of skm to bone following muscular trauma

111
Q

Where is Myositis ossificans most often seen?

A

Upper or lower extremity

112
Q

How does Myositis ossificans present?

A

Suspicous “mass” at site of known trauma or as incidental finding on radiography

113
Q

What is Scleroderma (systemic sclerosis)?

A

Excessive fibrosis & collagen deposition throughout the body

114
Q

How does Scleroderma of skin commonly present?

A

Sclerosis of skin, manifesting as puffy & taut skin w/ absence of wrinkles

115
Q

What organ systems does slceroderma affect?

A
  • Renal
  • Pulmonary (most likely COD)
  • CV
  • GI system
116
Q

Who gets scleroderma?

A

75% female

117
Q

What is Diffuse scleroderma?

A

Widespread skin involvement, rapid progression, early visceral involvement

118
Q

What is Diffuse scleroderma assoc w/?

A

anti-Scl-70 Ab (anti-DNA topoisomerase I Ab)

119
Q

Clinical sx of CREST synd

A
  • Calcinosis
  • Reaynaud’s phenomenon
  • Esophageal dysmotility
  • Sclerodactyly
  • Telangiectasia
  • Limited skin involvement often confined to fingers & face
120
Q

What is the clincial course of CREST synd?

A

More benign clinical course

121
Q

What is CREST synd assoc w/?

A

Anti-Centromere Ab ( C fo CREST)

122
Q

What is Osteogenesis Imperfecta?

A

Cogenital defect of bone resorption resutling in structurally weak bone

123
Q

What causes Osteogenesis Imperfecta?

A

AD defect in collagen type I synthesis (used to make bone)

124
Q

What are the clinical features of Osteogenesis Imperfecta?

A
  • Multiple fractures of bone
  • Blue sclera d/t thinning sclera collagen that reveals underlying choroidal veins
  • Hearing loss
125
Q

What causes Vit D def?

A
  • Decreased sun exposure
  • Poor diet
  • Malabsorption
  • Liver failure
  • Renal failure
126
Q

What are the clinical features of Rickets

A
  • Pigeon-breast deformity: inward bending of ribs
  • Frontal bossing
  • Rachitic rosary d/t osteoid dep @ costochondral junction
  • Bowing of legs
127
Q

Who gets Rickets?

A

MC arises in children <1 yo

128
Q

What are the clinical features of Osteomalacia?

A
  • Inc risk of bone fracture d/t inadequate mineralization
  • Dec serum Ca, dec P, inc PTH & Inc alk phos
129
Q

What is Osteomyelitis?

A

Infection of marrow & bone. MC bacterial arising by hematogenous spread

130
Q

How does Osteomyletis arise in children?

A

Tranisent bacteremia that seeds metaphysis

131
Q

How does osteomyelitis arise in adults?

A

Open-wound bacteremia that seeds epiphysis

132
Q

What are the causes of Osteomyelitis?

A
  • S. aureus→ MCC (90%)
  • N. gonorrhoeae→ sexually active young adults
  • Salmonella→ sickle cell dz
  • Pseudomonas→DM or IV drug abusers
  • TB→ vertebrae (Potts dz)
133
Q

Whare are the clinical features of osteomyelitis?

A
  • Bone pain w/ systemic signs of infection
  • Lytic focus (abscess) surrounded by sclerosis of bone on x-ray
  • Lytic focus→ sequestrum
  • Sclerosis→ involucrum
  • Dx made by blood culture
134
Q

What is avascular (aseptic) necrosis?

A

Ischemic necrosis of bone & BM

135
Q

What are the causes of avascular (aseptic) necrosis?

A
  • Trauma or fracture (MC)
  • Steroids
  • Sickle cell anemia (dactylitis)
  • Caisson dz (gas emboli, us N, in bone)
136
Q

What are the complications of avascular (aseptic) necrosis?

A

Osteoarthritis & fracture

137
Q

What are Osteomas?

A

Benign tumor of bone

138
Q

Where do osteomas commonly arise?

A

Surface of facial bones

139
Q

What are osteomas assoc w/?

A

Gardner synd: Familial adenomatous polyposis w/ fribomatosis in retroperitoneum & osteomas of facial bone

140
Q

What is Osteoid Osteoma?

A

Benign tumor of osteoblasts (that produce osteoid) surrounded by a rim of reactive bone (osteoma)

141
Q

Who do osteoid osteomas occur in?

A

young adults <25 yo (MC in males)

142
Q

Where do osteoid osteomas arise?

A

cortex & diaphysis of long bones (femur)

143
Q

What resolves the bone pain in oteoid osteoma?

A

Aspirin

144
Q

What does imaging of an osteoid osteoma reveal?

A

Bony mass (<2cm) w/ a radiolucent core (osteoid)

145
Q

What is an osteoblastoma?

A

Similar to osteoid osteoma but larger (>2cm), arise in vertebrae & presents as bone pain that does NOT respond to aspirin

146
Q

What is a Chondroma?

A

Benign tumor of cartilage that arises in the medulla of small bones of hands & feet

147
Q

What are the char of metastatic tumors of bone?

A
  • MC than 1° tumors
  • Osteolytic (punched-out) lesions
  • Prostatic CA classically produces osteoblastic lesions
148
Q

What are causes of 2° Gout?

A
  • Leukemia & myeloproliferative disorders (inc cell turn over)
  • Lesch-Nyhan synd
149
Q

What is Lesch-Nyhan synd?

A
  • X-linked def of hyoxanthine-guanine phosphoribosyltransferase (HGPRT)
  • Presents w/ mental retardation & self-mutilation (bite fingers & lips)
150
Q

What is a Lipoma?

A

MC benging soft issue tumor in adults. Benign tumor of adipose tissue

151
Q

What is a liposarcoma?

A

MC malignat soft tissue tumor in adults. Malignant tumor of adipose tissue. Lipoblasts are the char cell**

152
Q

What are Rhabdomyomas?

A

Benign tumor of skm

153
Q

What is cardiac rhabdomyoma assoc w/?

A

Tuberous sclerosis

154
Q

What are Rhabdomyosarcomas?

A

Malignant tumor of skm. MC malignant soft tissue tumor in children

155
Q

What are the char cells of Rhabdomyosarcomas?

A

Rhabdomyoblasts; desmin +

156
Q

What are the common locations of Rhabdomyosarcomas?

A
  • MC site is the head & neck
  • Vagina is the classic site in girls <5yo
157
Q

What is X-linked muscular dystrophy?

A

Degenerative disorder of skm char by muscle wasting & replacement of skm by adipose tissue

158
Q

What mutations are involved in X-linked muscular dystrophy?

A

Dystrophin→ anchors muscle cytoskeleton to the extracellular matrix; mut are often spon d/t large gene size

159
Q

What is the cause of Duchenne muscular dystrophy?

A

Deletion of dystrophin

160
Q

How does Duchenne muscular dystrophy present?

A
  • Proximal muscle weakness at 1 year of age, progresses to involve distal muscles
  • Calf pseudohypertophy (lage d/t fat)
  • Serum creatinine kinase is elevated
161
Q

What is the COD in Duchenne muscular dystrophy?

A

Cardiac or resp failure (myocardium commonly involved)

162
Q

What is Becker muscular dystrophy?

A

Caused by mutated dystrophin→ clincially results in milder dz