Bones of the axial and appendicular skeleton + base of the skull are formed via what process?
Cartilage model (chondrocytes) → Woven bone (Osteoclasts/blasts)
Later remodel to Lamellar bone
When do you see woven bone in adults?
After fx and Pagets disease
What bones are formed by membranous ossification?
Calvarium and facial bones - no cartilage model
What do osteoblasts differentiate from?
Mesenchymal stem cells - secrete collagen and catalyze mineralization
What do osteoclasts differentiate from?
Chronic ↑PTH has what effect on bone?
Catabolic - osteitis fibrosa cystica
Estrogen has what effect on bone?
⊣ apoptosis in osteoblasts
→ apoptosis in osteoclasts
What causes Achondroplasia?
Constit active FGFR3 - inhibit chondrocyte proliferation
Sporadic - adv. paternal age
some AD inheritance
S/S of Achondroplasia?
Failure of longitudinal long bone growth (endochondral ossification)
Short limbs, large head
How do you diagnose osteoporosis?
DEXA ≤ -2.5
Normal bone mineralization and lab values
What are indications of type 1 (post-men) osteoporosis?
Femoral neck fx & distal radius fx
How do you treat osteoporosis?
PTH - intermittant
Denosumab - anti-RANKL
SS of Osteopetrosis?
Thickened dense bones prone to fx
Pancytopenia and EM hematopoiesis
Cranial nerve impingement and palsies
What drives the symptoms of osteopetrosis? What can cure it?
Mutations in carbonic anhydrase II
Osteoclasts can't make enough acid
BMT - OC are from monocytes
What effect does vitamin D deficiency have on bone?
↓ mineralization/calcification of osteoid
*hyperactivity of osteoblasts - ↑ALP
What is the only lab value that is incresaed in Paget disease of bone?
Ca, PO4 and PTH are nomral
What are other symptoms of Paget disease of bone?
↑Hat size and Hearing loss
What isthe most common site for AVN?
Femoral head - insufficiency of medial circumflex femoral a.
What causes AVN?
Trauma, high-dose corticosteroids, alcoholism, sickle cell
What are the 2 benign primary tumors of bone?
Giant Cell tumor
A 25 yo man has a tumor in the epiphyseal end of a long bone with a soap bubble appearance on XR - what is it?
Giant cell tumor - locally aggressive, benign
Mature bone w/ cartilaginous cap, rarely transforms
Males < 25
What is the 2nd most common 1˚ malignant tumor of bone? What does imaging show?
codman triangle or sunburst on XR
Who gets an osteosarcoma and where does it occur?
Bimodal - 10-20 and >65
Metaphysis of long bones, often around knee
What predisposes to osteosarcoma?
Pagets disease of bone
Who gets Ewing Sarcoma? Where does it occur?
Boys < 15
Diaphysis of long bones, pelvis, scapula, and ribs
Small blue malignant tumor
Onion skin appearance of bone
Where do chondrosarcomas occur? Who get them?
Pelvis, spine, scapula, humerus, tibia, or femur (diaphysis)
Men 30-60 yo
An expansive glistening mass within the medullary cavity is a description of what?
How do you distinguish between osteoarthritis and RA?
OA: Pain after use or at end of day
RA: Morning stiffness > 30min, improve w/ use
What is RA mediated by?
Type III and IV hypersensitivity
What antibodies can be seen in RA? What predisposes to it?
⊕ rheumatoid factor (IgG)
Anti-cyclic citrullinated peptide Ab = more specific
What are examples of disease modifying agents used to treat RA?
S/S of Sjogren syndrome
Xerophthalmia = ↓ tear producition → corneal damage
Xerostomia = ↓ saliva prodcution → dental caries
Bilateral parotid enlargement
What might a unilateral parotid enlargement in a patient with Sjogren syndrome suggest?
What antibodies are seen in Sjogren? (2)
SS-A = anti-Ro
SS-B = anti-La
What is the most common cause of gout?
Underexcretion of uric acid - 90%
EtOH consumption - metabolites compete w/ uric acid for excretion
Precipitation of monosodium urate crystals
Needle-shaped ⊖birefringent (yellow under parallel)
Red, swollen, painful joint
Tophus in external ear, olecranon bursa, achilles tendon
How do you treat an acute gout attack? Chronic?
Acute = NSAID, glucocorticoids, colchicine
Chornic = allopurinol, febuxostat
What types of crystals are seen in pseudogout?
Basophilic rhomboid, weakly ⊕ birefringent (blue when parallel)
What diseases might be associated with pseudogout?
HyperPTH and Hypo PTH
What are the 3 most common causes of infectious arthritis? In sexually active people?
S. aureus, Streptococcus, N. gonorrhoeae
What are the 4 seronegative spondyloarthropaties - what are they associated with?
PAIR - HLA-B27
IBD - w/ ankylosing spondylitis or peripheral arthritis
Dactyitis (sausage fingers)
Pencil in cup
CID of spine and sacroiliac joints
Ankylosis - stiff spine - bamboo spine
Reactive Arthritis (Reiter syndrome)
Conjunctivis, urethritis, arthritis
Post GI - Shigella, Salmonella, Yersinia
What is the classic presentation of Lupus (SLE)
Rash, joint pain, and fever in a female of reproductive age and African descent.
What antibodies are sensitive for SLE? Drug-induced lupus?
ANA - sensitive not specific
Antihistone = drug induced
What antibody is both specific for SLE and associated with poor prognosis?
Poor prognosis associated with renal disease
Specific for SLE
Lupus nephritis (type III) can cause which 2 diseases?
Nephritic: Diffuse proliferative glomerulonephritis
Nephrotic: Membranous glomerulonephritis
What do you use to treat SLE?
NSAIDs, steroids, immunosuppressants, hydroxychloroquine
Widespread noncaseating granulomas in a black female is indicative of what?
What 2 enzymes are elevated in Sardoidosis?
Pain/stiffness in hips/shoulders + fever, malaise, and weight loss
↑ESR, CRP, normal CK
Responds to low-dose corticosteroids
How do you treat fibromyalgia?
Antidepressants - TCA, SNRI
What is polymyalgia rhematica associated with?
Temporal (giant cell) arteritis
Endomysial inflammation with CD8 T cells is characterisitic of what?
Polymyositis: progressive symmetrical proximal weakness
Perimysial inflammation and atrophy with CD4 Tcells?
Dermatomyositis: Malar rash, "shawl and face" rash, heliotrope rash, Gottron papules, mechanic's hands
↑ risk of occult malignancy
↑CK, ⊕ANA, ⊕anti-Jo-1, ⊕anti-SRP, and ⊕anti-Mi- antibodies are indicative of what?
How can you differentiate Mysathenia Gravis and Lambert-Eatin myasthenic syndrome?
MG = worsens w/ use, improves with AChE inhibitor
Lambert-Eaton = improves with use, no response to AChEi
Auto-Antibody to postsynaptic ACh receptor
Ptosis, diplopia, weakness
Associated w/ thymoma, thymic hyperplasia
Lambert-Eaton myasthenic syndrome
Auto-antibodies to presynaptic Ca channel → ↓ACh release
Proximal muscle weakness, autonomic symptoms (dry mouth, impotence)
Small cell lung CA
Metaplasia of sk. muscle to bone following trauma
Excessive fibrosis and collagen deposition throughout body
Widespread skin involvement, rapid progression, early visceral involvement
Anti-Scl-70 antibody - DNA-topo I
Limited skin - fingers and face only
CREST - antiCentromere antibody