Musculoskeletal and Derm Flashcards
What type of mutation and in what gene causes achondroplasia?
Activating mutation in FGFR3
What is the probability two heterozygous achondroplasia parents will have a child with the disease?
50% because homozygous dominant dies in utero
What bone tumor appears as a peduncle with a cartilage cap?
Osteochondroma
“osteoCHondroma = CHunk of bone”
What bone tumor has a soap bubble appearance on X ray?
Osteoclastoma (giant cell tumor)
“osteoCLastoma = CLean = soap bubbles”
What bone tumor has Codman’s triangle and sunburst appearance on X ray?
Osteosarcoma
“osteoSarComa = Sunburst, Codman’s triangle”
What bone tumor is found in the diaphysis and has an onion skin appearance?
Ewing sarcoma
“chicken wings (ewing) and onion rings (onion skin)”
What translocation is associated with ewing sarcoma?
t(11;22)
What is the average age of presentation for the 4 primary bone tumors?
Osteochondroma, osteoclastoma, osteosarcoma, ewing sarcoma
Osteochondroma:
What metastatic cancers are found in bone?
“Permanently Relocated Tumors Like Bone”
Prostate, renal cell, testes/thyroid, lung, breast
GU association - kidney, prostate, testes
What GI drugs can increase risk for osteoporosis?
PPIs or H2 blockers - need acid to absorb Ca
What are the 2 side effects of bisphosphonates?
Erosive esophagitis and osteonecrosis of the jaw
What is the mechanism of Teriparatide?
PTH analog that when given as pulsitile stimulates osteoblast bone formation
What is the mechanism of Denosumab?
Monoclonal antibody against RANKL (blocks osteoclast stimulation)
What gene mutation causes osteoporosis?
Carbonic anhydrase 2 (osteoclasts cannot make the acidic environment needed to resorb minerals)
What is the pathogenesis of Paget’s disease of the bone?
Lytic - osteoclasts overstimulated
Mixed - osteoblasts activated to catch up
Sclerotic - osteoclasts burn out
Increased hat size and hearing loss
Paget’s disease of the bone
How is ALP affected in osteoporosis, osteoporosis, and Paget’s disease of the bone?
ALP is a marker of osteoblasts
Osteoporosis (decreased osteoblasts) - normal
Osteopetrosis (decreased osteoclasts) - normal
Paget’s disease (increased osteoblasts and clasts) - increased
What causes Osteitis Fibrosa Cystica?
What 4 changes are seen in the bone?
High PTH Brown tumors (cysts lined with fibrous tissue and filled with blood = due to fast osteoclast breakdown), subperiosteal bone resorption in middle fingers, tapered distal clavicles, salt and pepper skull
What is McCune Albright Syndrome?
Precocious puberty + cafe au lait spots + polyostotic fibrous dysplasia
What is polyostotic fibrous dysplasia?
Bone is replaces with fibroblasts and collagen
What is Albright Hereditary Osteodystrophy (pseudohypoparathyroid)?
What bone pathology is associated?
Renal PTH resistance - high PTH + low Ca/high PO4
Causes Osteitis fibrosis cystica
What 4 structures may be injured in a posterior hip dislocation?
Circumflex femoral arteries (medial and lateral)
Femoral vein
Femoral nerve
Head of the femur
What ligament is most commonly damaged in an ankle sprain?
What other two are also common?
The 3 lateral ligaments are more common than the medial deltoid ligament.
Most common - anterior talo-fibular ligament
“Always Tears First”
Other lateral ligaments - calcaneo-tibular, posterior talo-fibular
What 2 antibodies are most useful in diagnosing RA?
RF and ACPA (anti-citrullinated protein Ab)
What HLA gene is associated with RA?
HLA-DR4
What two ways can NSAIDs cause renal damage?
Ischemia (loss of PGs that dilated the afferent arteriole and control RBF) and interstitial nephritis
What joint disease can lactic acidosis cause?
Gout - organic acids compete for the same renal transporter as uric acid
What is the most common trigger for an acute gout attack?
Alcohol consumption - competes for the same renal transporter as uric acid
Allopurinol can increase the toxicity of what two drugs?
6-mercaptopurine and azathioprine
What is the mechanism of Febuxostat?
Xanthine oxidase inhibitor
What is the mechanism of Probenecid?
Inhibits uric acid resorption in the kidneys
What effect does Colchicine have on microtubules?
Stabilizes them
What pathology is associated with chonedrocalcinosis?
Pseudogout
What pathology is associated with a pencil-in-cup deformity of the DIP joints?
Psoriatic arthritis
What type of arthritis is associated with dactylics?
Psoriatic arthritis
What type of arthritis is associated with uveitis, aortic regurgitation, and conduction abnormalities?
Ankylosing spondylitis
What is reactive arthritis?
What triggers an episode?
Conjunctivitis, urethritis, and arthritis
“Cant see, can’t pee, can’t climb a tree”
Post GI infection (shigella, salmonella, yersinia, campylobacter) or chlamydia
What is used to treat the seronegative spondyloarthropathies?
TNFa inhibitors (etanercept, infliximab, and adalimumab)
Child
Systemic-onset Juvenile idiopathic arthritis (initially looks like leukemia, then the arthritis comes)
What type of arthritis is caused by gonorrhea?
What other finding is associated with gonococci arthritis?
Septic migratory arthritis
Pustules on the skin
Painless oral ulcers + non-erosive arthritis + pericarditis + psychosis + low blood cells or hemolytic anemia
SLE
ANA+ (6 conditions)
Sjogrens syndrome, scleroderma, polymyositis/dermatomyositis, RA, juvenile idiopathic arthritis, and mixed CT disease
anti-dsDNA Abs
Lupus nephritis
anti-Smith Abs
Specific for SLE
anti-histone Abs
Drug-induced SLE
What drugs cause drug-induced lupus?
“SHIPP”
Sulfonamides, hydralazine, isoniazid, phenytoin, procainamide
anti-phospholipid (anti-cardiolipin) Abs
Hypercoagulability in SLE
What immunologic change is seen in SLE?
Decreased C3 and C4 = increased risk for infection
What can be used to treat SLE?
Glucocorticoids, cyclophosphamide, NSAIDs, hydroxychloroquine (antimalarial and DMARD)
Ulcerated fingers with telangectasias
Sclerodermas
anti-DNA topoisomerase 1 (anti-scl-70) Abs
Diffuse scleroderma
anti-centromere Abs
CREST
What is seen in CREST syndrome?
Calcinosis (subepithelial Ca), raynaud phenomenon, esophageal dysmotility, sclerodactyly, and telangectasias
What triad of symptoms is seen in Sjogrens syndrome?
Dry eyes + dry mouth + arthritis
“Cant see, can’t spit, can’t climb up shit”
anti-Ro, anti-La
Sjogren syndrome (Ro = SSA, La = SSB)
What third autoAb is seen in Sjogrens?
RF
Proximal joint pain without weakness + systemic symptoms (fever, malaise, weight loss) in a little old lady
Labs - elevated ESR, normal CK
Polymyalgia rheumatica
What other condition is associated with polymyalgia rheumatica?
Temporal (Giant cell) arteritis
Proximal joint pain with weakness + systemic symptoms (fever, malaise, weight loss)
Polymyositis
What is the pathogenesis of polymyositis?
CD8+ T cell inflammation of endomysial muscle
anti-Jo1 Abs
Polymyositis
Purple heliotrope rash, shawl rash, and gottrons papules
Dermatomyositis
What 2 other conditions are associated with fibromyalgia?
Depression and anxiety
What is parakeratosis?
What condition is associated with it?
Nuclei retained in the stratum corneum
Psoriasis
What is the pathogenesis of psoriasis?
Overproduction of new skin cells
What skin pathology is described as “stuck on”?
Seborrheic keratosis
Keratin filled cysts
Seborrheic keratosis
Horn growing from the skin
Seborrheic keratosis
What is the Leser-Trelat sign?
Sudden appearance of multiple seborrheic keratoses that signified an underlying visceral malignancy (classically GI)
What pathology is associated with decreased melanin?
What pathology is associated with decreased melanocytes?
Decreased melanin - albinism (tyrosinase deficiency)
Decreased melanocytes - vitiligo (autoimmune destruction of melanocytes)
What is the first step in management of a patient with necrotizing fasciitis?
Surgical wond debridement
anti-desmoglein Abs
Pemphigus vulgaris
“DAMN is a vulgar word” Desmosomes, Acantholysis, Mouth, Nikolskys sign
anti-hemidesmosome Abs
Bullous pemphigoid
“BPH” Bullous Pemphigoid Hemidesmosomes
What does Erythema multiforme look like?
What can trigger it?
Many things, including targetoid rash with central necrosis
Drug reaction, HSV
What drugs are known for causing SJS?
Seizure drugs, Sulfa drugs, penicillins, allopurinol
Saw-tooth lymphocytic infiltrate at the dermal-epidermal junction
Lichen planus
What infection is associated with Lichen planus?
Hepatitis C
Papule’s that feel like sand paper
Actinic keratosis
What anti-cancer drug is used to treat actinic keratosis?
5-flurouracil
What pathology is most strongly associated with Erythema nodosum?
Sarcoidosis
Herald patch followed by christmas tree distribution of plaques
Pityriasis rosea (HHV6/7 Roseola reactivation)
Keratin pearls
Squamous cell CA
What skin cancer presents as an ulcer?
Squamous cell CA
Waiter’s tip
Erb-Duchenne palsy (C5/C6 root)
- Arm hangs to side (axillary - deltoid, suprascap n - suprascap m)
- Internal rotation (acillary - teres minor)
- Pronation (musculocutaneous - biceps)
Claw hand
Klumpke’s palsy (inferior trunk)
- PIP extension + DIP flexion (lumbricles)
- Intrinsic muscle atrophy (ulnar - interosseous)
- Thenar/hypothenar atrophy (median, ulnar)
What is the difference between the ulnar claw and pope’s blessing hand?
Ulnar claw = at rest (ulnar nerve damage - lumbricles 4/5)
Pope’s blessing = only when making a fist (median nerve damage - lumbricles 2/3)
What is the difference between median claw and OK gesture?
Median claw = at rest (medicine nerve damage - lumbricles 2/3)
OK gesture = only when making a fist (ulnar nerve damage - lumbricles 4/5)
What nerve is damaged with fracture of the humerus at the surgical neck?
At the shaft?
Axillary nerve
Radial nerve
What nerve is damaged in a pelvic fracture?
What would you find?
Femoral nerve
Loss of hip flexion/knee extension (can’t kick a ball), sensation loss over anterior thigh and medial leg
What nerve is damaged in anterior thigh dislocation?
Obturator nerve
What nerve is damaged in a posterior thigh dislocation?
What clinical finding would be seen?
What infection can cause damage to the same nerve?
Superior gluteal nerve
Trendelenberg gait
Polio
Loss of sensation on the sole of the foot
Tibial nerve injury
Foot drop
Common fibular nerve injury
Wrist drop
Radial nerver injury
