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Flashcards in Pathology - musculoskeletal Deck (25):
1

Failure of longitudinal bone growth

Achondroplasia

Constitutive activation of FGF-receptor 3 inhibits chondrocyte proliferation

Membranous ossficiation not affected, so large head but small body

2

Loss of trabecular bone mass w/ normal bone mineralization

Osteoporosis

Type 1: incr. bone resorption due to low estrogen levels
Type 2: old people, tx w/ bisphosphonates, PTH analogs, SERMs, denosumab (monoclonal Ab against RANKL)

3

Failure of normal bone resorption due to defective osteoclasts leads to thick dense bones prone to fracture

Osteopetrosis

Bone also fills marrow, so pancytopenia

Carbonic anhydrase mutation

Can also narrow foramina (leading to cranial nerve palsies)

Tx: bone marrow transplant

4

Defective mineralization/calcification of osteoid

Osteomalacia

Vit. D deficiency (low Vit D --> low serum Ca --> high PTH --> loss of PO4)

Look for incr. Alk Phos (hyperactivity of osteoblasts)

5

Localized disorder of bone remodeling, mosaic pattern of woven and lamellar bone

Paget disease of bone

Incr in osteoblastic and osteoclastic activity

incr blood flow from AV shunts --> high output heart failure

incr. risk of osteogenic sarcoma

6

Painful infarction of bone and marrow

Osteonecrosis/avascular necrosis

Femoral head, due to insufficiency of medial circumflex femoral artery

ASEPTIC: Alcoholism, Sickle cell disease, Storage, Exogenous/Endogenous steroids, Pancreatitis, Trauma, Idiopathic, Caisson (decompression disease)

7

Knee tumor vs. cartilaginous cap

Benign bone tumors

Giant cell tumor: multinucleated giant cells, end of long bones

Osteochondroma: most common (exostosis of bone), mature bone with cartilaginous cap

8

Osteosarcoma vs. Ewing sarcoma (malignant bone tumors)

Osteosarcoma - sunburst pattern, Codman triangle (elevation of periosteum), surgical resection!

Ewing sarcoma - young boys, anaplastic small blue cell, onion skin periosteal reaction, t(11;22)

9

Rheumatoid arthritis immune mechanism

Type 3 and Type 4 hypersensitivity

Look for rheumatoid factor (anti-IgG antibody), anti-CCP, HLA-DR4

10

Destruction of salivary glands by lymphocytic infiltrates

Sjogren's

Sx: inflammatory, anti-SSA/anti-SSB (Ro/La)

Complications: dental caries, MALT lymphoma

11

Mechanisms of gout

Underexcretion of uric acid (90% of pts): idiopathic, alcohol (competes for excretion sites in the kidney)

Overproduction of uric acid (10%): PRPP excess, incr. cell turnover (tumor lysis), Lesch-Nyan

negatively bifringent needle-shaped (yellow under parallel light)

12

Gout treatment regimens (acute and chronic)

Acute: NSAIDs, steroids, colchicine (inhibits microtubule polymerization in neutrophils)

Chronic: allopurinol, febuxostat (xanthine oxidase inhibitor)

13

Pseudogout

deposition of calcium pyrophosphate crystals in the joint space

basophilic, rhomboid crystals that are weakly birefringement in large joints (the knee!)

tx: NSAIDs, steroids, colchicine (ppx)

14

Seronegative spondylopathies (PAIR) - no rheumatoid factor (no anti-IgG)

HLA-B27

psoriatic arthritis
ankylosing spondylitis
IBD
reactive arthritis

15

Classic triad of reactive arthritis

Conjunctivitis, Urethritis, Arthritis

Can't see, can't pee, can't bend my knee

16

Mechanism of lupus nephritis

Type 3 hypersensitivity

Nephritis - diffuse proliferative glomerulonephritis

Nephrotic - membranous glomerulonephritis

17

Causes of death in SLE

cardiovascular disease

infections

renal disease

18

SLE antibodies

anti-nuclear (ANA)** most sensitive
anti-dsDNA
anti-Smith (directed against snRNPs)
anti-histone (drug-induced lupus)

decr. C3, C4, due to immune complex formation

19

Anticardiolipin antibodies, lupus anticoagulant

Antiphospholipid syndrome

history of thrombosis (arterial/venous) or spontaneous abortion

note: false-positive VDRL, prolonged PTT

20

Immune-mediated widespread non-caseating granulomas

Sarcoidosis

also, elevated serum ACE levels, incr. CD4:CD8 ratio

hypercalcemia (incr. VitD activation in macrophages)

21

Pain/stiffness in shoulders/hips, fever, malaise, weight loss

Polymyalgia rheumatic

No muscular weakness!

Incr. ESR, CRP, Normal CK

Rapid response to low-dose steroids

22

Antibodies in polymyositis/dermatomyositis

ANA, anti-Jo, anti-SRP, anti-Mi-2

proximal muscle weakness (most often in shoulders)

look for endomysial inflammation with CD8 T cells

23

Dermatomyositis

vs. polymyositis: also involves malar rash, papules on knuckles (Gottron), periorbital rash (heliotrope)

incr. risk of malignancy

perimysial inflammation and atrophy with CD4 T cells

24

Metaplasia of skeletal muscle into bone following trauma

Myositis ossificans

May present as suspicious mass at site of known trauma or as incidental finding on radiography

25

Autoimmunity, noninflammatory vasculopathy, collagen deposition

Systemic scleroderma

Diffuse: skin involvement, rapid progression, early visceral involvement. Associated with ***anti-Scl70 antibody*** (anti-DNA topoisomerase antibody)

Limited: CREST - calcinosis, Raynaud, esophageal, sclerodactyly, telangiectasia. Associated with ***anti-centromere antibody***