MSK, Skin and Connective Tissue Flashcards
Epidermis Layers (from surface to base)
stratum Corneum, Lucidum, Granulosum, Spinosum (desmosomes), Basale (stem cell site)
- Californias Like Girls in String Bikinis
- calluses are thickened stratum corneum only
Epithelial cell junctions in order
- tight junctions - zonula occludens (claudins and occludens)
- adherens junction - zonula adherins, cadherins (Ca dependent)
- desmosome - macula adherins (keratin interactions)
- gap junction
- hemidesmosomes - conects keratin in basal cells to underlying Bm
- integrins - membrane proteins that bind collagen and laminin in the basement membrane (maintain tissue integrity)
injury associated with chronic kneeling
prepatellar bursitis ("housemaids knee")
- knee pain , swelling, redness, crepitance, fluctuant edemarotator cuff muscles
SITS
- supra/infraspinatus, teres minor, subscapularis
supraspinatus function
- most common rotator cuff injury (empty can test)
- abducts the arm initially
- innervated by suprascapular nerve
infraspinatus function
- laterally rotates the arm
- innervated by suprascapular nerve
teres minor function
- adducts and laterally rotates the arm
- innervated by the axillary nerve
subscapularis function
- medially rotates and adducts the arm
- innervated by subscapular nerve
carpal bone injuries
- scaphoid most commonly fracture - avascular necrosis
- dislocation of the lunate –> carpal tunnel syndrome
- FOOSH damages hook of hamate –> ulnar nerve injury
radial head subluxation
- nursemaids elbow
- tear of annular ligament
erbs palsy
C5-6 injury
- infants due to lateral traction on neck during delivery, adults due to trauma
- muscle deficits: deltoid, supraspinatus (abduction), infraspinatus (lateral rotation), biceps brachii (flexion, supination)
klumpke palsy
lower trunk injury (C8-T1)
- infants due to upward force on arm during delivery, adults trauma
- deficit in intrinsic hand muscles leads to total claw hand
winged scapula
- lesion of the long thoracic nerve
- axillary dissection after mastectomy, stab wounds
- affects the serratus anterior
- cannot abduct arm above horizontal, winged scapula
Axillary (C5-C6) injury
- fractured surgical neck of humerus
- anterior dislocation of humerus
- presentation: flattened deltoid, loss of arm abduction at shoulder, loss of sensation over deltoid and lateral arm
Musculocutaenous (C5-C7) injury
- injury due to upper trunk compression
- loss of forearm flexion and supination, loss of sensation over lateral forearm
Radial nerve (C5-T1) injury
- midshaft fracture of humerus, compression of axilla (crutches or saturday night palsy)
- writs drop, dec grip strength, loss of sensation of posterior arm/forearm and dorsal hand
Median nerve (C5-T1) injury
- supracondylar fracture of humerus (proximal lesion, carpal tunnel syndrome and wrist laceration
- “Ape hand” and “Pope’s blessing”
- loss of writs and lateral finger flexion, thumb opposition, lumbricals of 2nd and 3rd digits
Ulnar nerve (C8-T1) injury
- fracture of medial epicondyle of the humerus “funny bone”, fractured hook of hamate
- “ulnar claw” on digit extension, radial deviation on write flexion, loss of flexion of wrist and medial fingers
recurrent branch of the median nerve injury (C5-T1)
- superficial laceration of palm
- “Ape hand”, loss of thenar opposition, abduction, flexion of thumb
- no sensation loss
obturator (L2-L4) nerve injury
- pelvic surgery, ant hip dislocation
- travels through the obturator foramen
- decreased medial thigh sensation and decreased adduction
femoral (L2-L4) nerve injury
- pelvic fracture, mass involving the ilopsoas
- decreased thigh flexion and leg extenion
- decreased patellar reflex
common peroneal (L4-S2) nerve injury
- trauma or compression of lateral aspect of leg, fibular neck fracture
- foot drop with loss of eversion and dorsiflexion
- “steppage gait”
- PED = Peroneal Everts and Dorsiflexes, if injured foot dropPED
tibial nerve (L4-S3) nerve injury
- knee trauma, Baker cyst, tarsal tunnel syndrome
- inability to curl toes, loss of sensation on sole of foot, loss of inversion and plantar flexion
- TIP = Tibial Inverts and Plantarflexes, if injured, cannot stand on TIP toes
superior gluteal (L4-S1) injury
- post hip dislocation, buttocks injection, polio
- trendelenburg sign/gait – pelvis tilts due to weak hip abduction, lesion is contralateral to side of hip that drops, ipsilateral to leg they stand on
inferior gluteal (L5-S2) injury
- post hip dislocation or buttocks injection
- difficulty climbing stairs/rising from seated position
- loss of hip extension
Type 1 muscle fubers
- slow, red (more mito and myoglobin), oxidative phosphorylation
Type 2 muscle fibers
- fast, white, anaerobic glycolysis
Smooth muscle contraction cascade
- depolarization causes L type Ca channels to open, Ca enters and binds to calmodulin, Ca-calmodulin complex binds myosin light chain kinase, which stimulates myosin-actin binding
- NO/cGMP causes relaxation
endochondral ossifcation
- bones of axial and appendicular skeleton
- catilage made by chondrocytes and then osteoclasts/blasts replace with woven bone, gets remodeled to lamellar bone
membranous ossification
- bones of the calvarium and facial bones, woven bone formed directly without cartilage, later remodeled to lamellar boen
achondroplasia
failure of endochondral ossification due to constitutive activation of fibroblast growth factor (FGFR3) on short arm of chromosome 4
- > 85% of mutations are sporadic, 2/2 advanced paternal age
- AD inheritance
osteoporosis
- loss of bone mass and interconnections
- normal bone mineralization and labs
- treat with bisphosphonates, PTH, SERMs, rarely calcitonin, densumab (RANKL monoclonal Ab)
osteopetrosis
- defective osteoclasts
- thickened dense bones prone to fracture
- pancytopenia, extramedulalry hematopoiesis
- nerve impingement and palsies
osteomalacia
- rickets in kids
- defective mineralization/calcification of osteoid
- Vit D defect, dec Ca, inc PTH, inc ALP
Pagets disease of bone
increased osteoblastic and osteoclastic activity
- normal labs, inc ALP
- inc risk of osteosarcoma
- mosaic pattern of woven and lamellar bone
- hat size increase and hearing loss
giant cell tumor
- 20-40 years old, epiphyseal end of long bones
- locally agressive benign tumor
- “soap bubble” appearance
- multinucleated giant cells
osteochrondroma
- most common benign tumor
- males < 25 years old
- mature bone with cartilaginous cap
- rarely transforms to chondrosarcoma
osteosarcoma
2nd most common primary malignant bone tumor (after multiple myeloma)
- bimodal distribution 10-20 years old and > 65
- predisposing factors: Paget disease of bone, bone infarcts, radiation, familial retinoblastoma, Li-Fraumeni (germline p53)
- metaphysis of long bones, sunburst pattern, Codman triangle
Ewing Sarcoma
- boys < 15 years old
- commonly appears in diaphysis of long bones, pelvis, scapula, and ribs
- anaplastic small blue cell malignant tumor, aggressive but responsive to chemo
- “onion skin”
- 11:22 translocation
Chondrosarcoma
- rare, malignant, cartilaginous tumor
- Men 30-60 years old
- usually located in pelvis, spine, scapular, humerus, tibia or femur
- may be primary or from osteochondroma
- expansile glistening mass within the medullary cavity
rheumatoid arthritis
- mediated by cytokines
- Type IV HS reaction
- 80% + RF, anti-CCP more specific
- association with HLA-DR4
- no DIP involvement
Sjogren syndrome
- AI destruction of exocrine glands
- anti SSB and anti SSB (anti-Ro and anti-La) are antiribonucleoprotein antibodies
- complications include dental caries, MALT lymphoma (unilateral parotid enlargement)
causes of gout
- under-excretion
- overproduction of uric acid - Lesch-Nyan, PRPP excess, inc cell turnover, von Gierke disease
psuedogout
- calcium pyrophosphate crystals
- basophilic, rhomboid crystals
- associated with hemochromatosis, hyper and hypo PTH
psoriatic arthritis
- asymmetric, patchy involvement
- dactylitis (“sausage fingers”)
- pencil-in-cup deformity on xray
ank spon
- ankylosis, uveitis, and aortic regurg
- inflammation at tendon insertion sites (costo-chondral junctions –> monitor chest expansion)
SLE antibodies - which are specific, sensitive?
- ANA sensitive
- anti-histone sensitive for drug-induced lupus (procainamide, hydralazine, INH)
- anti-DNA and anti-Smith specific
sarcoidosis
- can be distinguished from other restrictive lung diseases by CD4:CD8 ratio > 2:1
- erythema nodosym, Bell palsy, uveitis and hypercalcemia due to inc alpha-hydroxylase-mediated Vit D activation
polymyalgia rheumatica
- associated with TCA
- inc ESR, CRP, normal CK
polymyositis
- proximal muscle weakness
- characetrized by endomysial inflammation with CD8 T cells and macrophages
- most often involves the shoulders
- inc CK, + ANA, + Anti-Jo, + Anti-SRP, + Anti-Mi-2 Abs
dermatomyositis
- polymyositis + malar rash
- Cottron papules, heliotrope rash, mechanics hands
- inc risk of occult malignancy
- CD4 T cells
- inc CK, + ANA, + Anti-Jo, + Anti-SRP, + Anti-Mi-2 Abs
myositis ossificans
- metaplasia of skeletal muscle to bone following muscular trauma
- “mass” at site of known trauma
Scleroderma antibody
Anti-Scl 70
- anti DNA topoisomerase I
CREST
Calcinosis, Raynaud, Esophageal dysmotility, Sclerodactyly and Telangiectasia
- anti Centromere Ab
albinism
normal melanocyte number with decreased melanin production due to decreased tyrosinase activity or defective tyrosine transport
- can also be due to failed neural crest migration
psoriasis
- increased stratum spinosum, decreased stratum granulosum
- Auspitz sign - pinpoint bleeding spots from exposure of dermal papullae when scales are scraped off
Leser-Trelat sign
- sudden appearance of multiple seborrheic keratoses, indicating an underlying malignancy
pemphigus vulgaris
- potentially fatal AI skin disorder with IgG Ab against desmoglien (component of desmosomes)
- flaccid intraepidermal bullae caused by acatholysis (separation of epidermal cells)
- oral mucosa is involved
- immuno shows reticular pattern
+ve Nikolsky sign
bullous pemphigoid
- IgG against hemidesmosomes
- Abs “bullow” the epidermis
- tense blisters containing eosinophils affect skin
- no oral mucosal involvement
- immuno shows linear pattern at epi-dermal junction
- ve Nikolsky sign
dermatitis herpetiformis
- pruritic papules, vesicles and bullae
- deposits of IgA at tips of dermal papillae
- celiac disease
erythema nodosum
- painful inflammatory lesions of subQ fat
- sarcoid, coccidiomycosis, histo, TB, strep infections, leprosy, and Crohn disease
lichen planus
- pruritic, purple polygonal planar papules and plaques
- sawtooth infiltrate of lymphocytes at dermal-epidermal junction
- associated with Hep C
pityriasis rosea
“herald patch” then christmas tree
- multiple plaques with collarette scale
- self-resolving in 6-8 weeks
sunburn
- UVA – tanning and photoaging
- UVB – sunburn
- PABA esters are potent UVB radiation absorbers and are in sunscreen
basal cell carcinoma
- most common skin cancer, locally invasive but almost never mets
- telangiectasias, rolled borders, central crusting or ulceration
- “palisading” nuclei
squamous cell carcinoma
- 2nd most common
- exposure to sunlight, immunosuppression, arsenic exposure
- locally invasive, may spread to lymph nodes and rarely mets
- histo: “keratin pearls”
keratoacanthoma
- variant of SCC that grows rapidly (4-6 weeks) and may regress spontaneously over months
melanoma
- S-100 tumor marker
- BRAF mutation
- vemurafenib (BRAF kinase inhibitor) may help those with BRAF V600E mutation
