Tight junction (aka zonula occludens)
prevents paracellular movement of solutes; composed of claudins and occludins
Adherens junction (aka zonula adherens)
below tight junction; forms belt connecting actin cytoskeletons of adjacent cells with cadherins
Ca2+ dependent adhesion proteins.
Loss of E-cadherin promotes...
Desmosome (macula adherens)
structural support via keratin interactions
Autoantibodies to the desmosome cause...
channel proteins called connexons permit electrical and chemical communication between cells
membrane proteins that maintain the integrity of basolateral membrane by binding to collagen and laminin in the basement membrane
connects keratin in basal cells to the underlying BM
Autoantibodies to the hemidesmosome leads to...
bullous pemphigoid (hemidesmosomes are down "bullo")
Anterior drawer sign tests for...
Posterior drawer sign tests for...
Valgus stress (abduction) tests for....
Varus stress tests for (adduction)....
pain on external rotation = medial meniscus pain on internal rotation = lateral meniscus
injury due to lateral force applied to planted leg; consists of damage to ACL, MCL and medial meniscus (or lateral meniscus)
Pudendal nerve block is given....
to relieve the pain of delivery into the ischial spine.
Rotator Cuff Muscles
Supraspinatus Infraspinatus Teres minor Subscapularis
-suprascapular nerve -abducts arm initially -most common rotator cuff injury
-suprascapular nerve -laterally rotates arm -pitching injury
-axillary nerve -adducts and laterally rotates arm
-subscapular nerve -medially rotates and adducts arm
The most commonly fractured carpal bone is...
the scaphoid bone and it is prone to avascular necrosis due to retrograde blood supply. It can be palpated in the anatomical snuff box.
Dislocation of the lunate may cause...
acute carpal tunnel.
A fall on an outstretched hand that damages the hook of hamate can cause...
ulnar nerve injury.
Carpal Tunnel Syndrome
entrapment of median nerve leading to parestesia, pain and numbness
Guyon Canal Syndrome
compression of the ulnar nerve classically seen in cyclists
Erb Palsy is an injury of the...
upper trunk caused by lateral traction on infant's neck during delivery or trauma in adults.
Erb Palsy Muscle/Functional Deficits
Deltoid/Supraspinatus - abduction (arm hangs by side) Infraspinatus - lateral rotation (arm is medially rotated) Biceps brachii - flexion, supination (arm extended and pronated)
Klumpke Palsy is an injury of the....
lower trunk due to upward force on infant arm during delivery or adult trauma.
Klumpke Palsy Muscle/Functional Deficits
total claw hand due to intrinsic hand muscle deficits
Thoracic Outlet Syndrome is a....
compression of lower trunk and subclavian vessels due to a cervical rib injury or a Pancoast tumor.
Thoracic Outlet Syndrome has the same deficits as...
Winged Scapula is an injury of...
the long thoracic nerve due either axillary node dissection after masectomy or stab wounds.
Winged Scapula Muscle/Functional Deficits
Serratus Anterior = cannot abduct arm above a horizontal position
Causes of injury to the axillary nerve (C5-C6)
fractured surgical neck of humerus; anterior dislocation of the humerus
Presentation of axillary nerve injury
-flattened deltoid -loss of arm abduction past 15 degrees -loss of sensation over delt and lateral arm
Cause of injury to musculocutaneous nerve (C5-C7)
upper trunk compression
Musculocutaneous Injury Presentation
-loss of forearm flexion/supination -loss of sensation over lateral forearm
Cause of injury to Radial nerve (C5-T1)
-midshaft fracture of humerus -compression of axilla due to crutches or sleeping with arm over chair
Presentation of radial nerve injury
-wrist drop -decreased grip strength -loss of sensation over posterior arm/forearm and dorsal hand
Cause of injury to Median nerve (C5-T1)
-supracondylar fracture of humerus -carpal tunnel syndrome or wrist laceration
Presentation of Median nerve injury
-ape hand and pope's blessing -Tinel sign (tingling on percussion) -loss of sensation over thenar eminence and dorsal/palmar aspects of lateral 3.5 fingers
Cause of injury to the Ulnar nerve (C8-T1)
fracture of the medial epicondyle of the humerous or fractured hook of hamate
Ulnar nerve injury presentation
-ulnar claw -loss of sensation over medial 1.5 fingers including hypothenar eminence
Injury to the recurrent branch of the median nerve
superficial palm laceration
Presentation of recurrent median nerve injury
ape hand -loss of thenar musclegroup -no loss of sensation
Interosseous Muscles DAB PAD
Dorsals ABduct Palmars ADduct
Lumbrical muscles act to...
flex and the MCP and extend at the PIP and DIP.
Obturator (L2-L4) injury is due to...
pelvic surgery and leads to decreased thigh sensation and decreased adduction.
Femoral (L2-L4) injury is due to...
pelvic fracture and leads to decreased thigh flexion and leg extension.
Common peroneal (L4-S2) injury is due to...
trauma or compression of the lateral aspect of the leg or fibular neck fracture.
Common peroneal injury presents with...
foot drop and loss of sensation on dorsum of foot
Tibial injury (L4-S3) can be due to...
knee trauma, baker cyst or tarsal tunnel syndrome.
Tibial injury presents with...
inability to curl toes and loss of sensation on the sole of the foot; if lesion is proximal, foot loses inversion and plantar flexion
Superior gluteal nerve (L4-S3) injury is due to...
posterior hip dislocation or polio.
Superior gluteal injury presents with..
Trendelenburg gait is when...
the pelvis tilts because the weight-bearing leg cannont maintain alignment of the pelvis through hip abduction
In Trendelenburg gait, the lesion is...
contralateral to the side of the hip that drops.
Inferior gluteal nerve injury is due to...
posterior hip dislocation.
Inferior gluteal nerve presentation
difficulty climbing stairs, rising from seated position; loss of hip extension
The sciatic nerve splits into...
the common peroneal and tibial.
Axilla/Lateral Thorax nerve and artery
long thoracic n. and lateral thoracic a.
Surgical neck of humerus nerve and artery
axillary n and posterior circumflex a.
Midshaft of humerus nerve and artery
radial n and deep brachial a.
distal humerus/cubital fossa nerve and artery
median n and brachial a.
Popliteal fossa nerve and artery
tibial n and popliteal a.
medial malleolus nerve and artery
tibial n and posterior tibial a.
Type 1 Muscle Features
-slow twitch -red fibers (from incresaed mitochondria/myoglobin) -increased oxidative phosphorylation --> sustained contraction
Type 2 Muscle Featured
-fast twitch -decreased mitochondria/myoglobin (white fibers) -increased anaerobic glycolysis
Weight training results in...
hypertrophy of fast-twitch muscle fibers.
cartilaginous model of bone is first made by chondrocytes; osteoclasts and osteoblasts later replace with woven bone and then remodel to lamellar bone
Endochondral ossification occurs in...
bones of the axial and appendicular skeleton and at the base of the skull
woven bone is formed directly without cartilage; later remodeled to lamellar bone
Membranous ossification occurs at...
bones of calvarium and facial bones
Osteoblasts act to...
build bone by secreting collagen and catalyzing mineralization.
Osteoblasts differentiate from...
mesenchymal stem cells in the periosteum.
multinucleated cells that dissolve bone by secreting acid and collagenases.
Osteoclasts differentiate from...
apoptosis of osteoblasts and promotes apoptosis of osteoclasts.
Under estrogen deficiency, bone experiences...
excess remodeling cycles and resorption leading to osteoporosis.
failure of longitudinal bone growth leading to short limbs.
In achondroplasia, membranous ossification is...
not affective leading to rather large head compared to limbs.
Achondroplasia occurs because...
constitutive activation of FGF3 inhibits chondrocyte proliferation.
loss of trabecular bone mass despite normal bone mineralization and lab values (Ca2+ and PO43-)
Diagnosis of osteoporosis is with...
a bone mineral density test (DEXA) with a T-score of
Type I Osteoporosis Features
-postmenopausal -increased bone resoprtion due to decreased estrogen levels -femoral neck fracture, distal radius fracture
Type II Osteoporosis Features
-senile osteoporosis -men and women >70
Treatment for Type II Osteoporosis
-Bisphosphonates -pulsatile PTH -SERMs -Denosumab
failure of normal bone resorption due to defective osteoclasts resulting in thickened bones prone to fracutre.
In osteopetrosis, bone fills the...
marrow space leading to pancytopenia and extramedullary hematopoeisis.
In osteopetrosis, osteoclasts have mutations that...
impair the ability of osteoclast to generate an acidic envirnoment necessary for bone resoprtion.
Osteopetrosis x-rays show...
bone in bone appearance.
Osteopetrosis can result in...
cranial nerve impingement and palsies as a result of narrowed foramina.
Osteomalacia/Rickets is due to...
Vitamin D deficiency. Defective mineralization/calcification of osteoid leads to soft bones that bow out.
Decreased vitamin D decreases....
serum calcium, which increases PTH which decresaes serum phosphate.
In osteomalacia/rickets, there is hyperactivity of osteoblasts leading to...
Paget's diseases of bone is due to...
increase in both osteoblastic and osteoclastic activity.
Lab levels in Paget's
-calcium, phosphorus, PTH normal -increased ALP
a mosaic pattern of woven and lamellar bone. See long bone chalk-stick fractures.
Paget's increases the risk of...
high-output heart failure and osteogenic sarcoma.
Signs of Pagets'
-increased hat size -hearing loss
Stages of Paget
1. Lytic (osteoclasts) 2. Mixed (osteoclasts and blasts) 3. Sclerotic (blasts) 4. Quiescent
Osteonecrosis can be caused by...
trauma, high dose corticosteroids, alcoholism and sickle cell.
The most common site for osteonecrosis is...
the femoral head due to insufficiency of medial circumflex femoral artery.
Giant Cell Tumor Features
-20-40 yrs old -located at epiphyseal end of long bones (often the knee) -benign -"soap bubble" appearance on xray -multinucleated giant cells
-bimodal distribution (10-20 yrs; > 65 yrs) -metaphysis of long bones (usually knee)
Predisposing factors for Osteosarcoma
-Paget disease of bone -bone infarcts -radiation -familial retinoblastoma -Li-Fraumeni
On x-ray, osteosarcoma shows...
Codman triangle or sunburst pattern.
Treatment of osteosarcoma
surgical en bloc resection and chemo
Ewing Sarcoma Features
-malignant, cartilaginous -men 30-60 yrs -usually in pelvis, spine, scapula, humerus, tibia or femur -can result from osteochondroma (rare)
Chondrosarcoma appears as...
an expansile glistening mass within the medullary cavity
mechanical - joint wear and tear destroys articular cartilage
Osteoarthritis Joint findings (6)
-subchondral cysts -sclerosis -osteophytes -eburnation -Heberden nodes (DIP) -Bouchard nodes (PIP)
Predisposing factors for osteoarthritis
-age -obesity -joint deformity -trauma
Classic Presentation of Osteoarthritis
Pain in weight-bearing joints after use; improves with rest. Knee cartilage loss begins medially (bowlegged). Noninflammatory
Treatment for Osteoarthritis
-NSAIDs -Intra-articular Glucocorticoids
Rheumatoid Arthritis Etiology
-autoimmune (inflammatory destruction of synovial joionts) -mediated by cytokines and type III and type IV HSR
Joint findings in RA (5)
-pannus formation (MCP, PIP) -rheumatoid nodules (fibrinoid necrosis) -ulnar deviation of fingers -subluxation -Baker cyst (popliteal foss)
Predisposing Factors for RA
-females -rheumatoid factor (anti-IgG antibody) -anti-cyclic citrullinated peptide -HLA-DR4
Classic Presentation of RA
-morning stiffness > 30 minutes -improves with use -symmetric -systemic symptoms (fever, fatigue, pleuritis, pericarditis)
Treatment for RA
-NSAIDs -glucocorticoids -disease-modifying agents (methotrexate, sulfasalazine, TNF-alpha inhibitors)
Sjogren syndrome is an...
autoimmune disorder characterized by destruction of exocrine glands (esp. lacrimal and salivary).
Sjogren syndrome predominantly affects...
females 40-60 yrs old.
Findings of Sjogren syndrome
-xerophthalmia -xerostomia -presence of anti-nuclear antibodies (SS-A and SS-B) -bilateral parotid enlargement
decreased tear production and corneal damage
decreased saliva production
Complications of Sjogren Syndrome
-dental caries -MALT lymphoma
acute inflammatory monoarthritis caused by precipitation of monosodium urate crystals in the joints.
Gout is associated with...
hyperuricemia which can be caused by underexcretion of uric acid (90%) or overproduction.
Overproduction of uric acid is seen in...
Lesch-Nyhan syndrome, increased PRPP, increased cell turnover and von Gierke disease.
Underexcretion of uric acid can be caused by...
In gout, the crystals are...
needle shaped and negatively birefringent (yellow under parallel light and blue under perpendicular light).
symptoms of gout
-asymmetric -swollen, red, painful joint -tophus formation
Classic manifestation of gout is...
painful MTP joint of the big toe (podagra).
Acute attacks of gout tend to occur after...
a large meal or alcohol consumption (alcohol competes for the same excretion sites as uric acid in the kidney).
Treatment of acute gout
-NSAIDs -Glucocorticoids -Colchicine
Treatment of chronic gout
-xanthine oxidase inhibitors (allopurinol or febuxostat)
Pseudogout presents with...
pain and effusion in a joint caused by deposition of calcium pyrophosphate crystals in the joint space.
On x-ray, pseudogout shows...
basophilic, rhomboid crystals athat are weakly positively birefringent.
Features of Pseudogout
-large joints (knee) - >50 yrs
Diseases associated with pseudogout include...
hemochromatosis, hyperparathyroidism, and hypoparathyroidism.
Treatment for Pseudogout
Common causes of infectious arthritis are...
S. aureus, Streptococcus and N. gonorrhaeae.
Gonococcal arthritis is an...
STD that presents as a migratory arthritis with an asymmetric pattern. S = synovitis (knee) T = tenosynovitis (hand) D = dermatitis (pustules)
Seronegative Spondyloarthropaties are...
arthritis wihtout rheumatoid factor and a strong association with HLA-B27.
Types of Seronegative Spondyloarthropathies (PAIR)
P = Psoriatic arthritis A = Ankylosing spondylitis I = Inflammatory bowel disease R = Reactive Arthritis
Psoriatic Arthritis Features
-joint pain/stiffness with psoriasis -asymmetric -dactylitis (sausage fingers) -"pencil in cup" on xray
Ankylosing spondylitis Features
-chronic inflammatory disease of the spine and sacroiliac joints -ankylosis (fusion of joints), uveitis and aortic regurgitation -bamboo spine on xray
Inflammatory Bowel Disease
-Crohn's and UC are often accompanied by ankylosing spondylitis or peripheral arthritis
Reactive Arthritis Class triad
-conjunctivits (and anterior uveitis) -Urethritis -arthritis (can't see, can't pee, can't bend my knee)
Reactive arthritis is usually due to...
post-GI (shigella, salmonella, yersinia or campylobacter) or chlamydia infxns.
Classic Presentation of Systemic Lupus Erythematous (SLE)
-rash -joint pain -fever -female of reproductive age -African descent
SLE is associated with...
Libman-Sacks endocarditis and Lupus Nephritis.
a wart-like vegetation on both sides of a valve.
Lupus nephritis is...
Type III HSR -nephritic: diffuse proliferative glomeurlonephritis -nephrotic: membranous glomeulonephritis
Common causes of death in SLE
-CV disease -Infxns -Renal disease
1. ANA (sensitive, not specific) 2. anti-dsDNA Abs (specific) 3. Anti-Smith antibodies (specific) 4. Antihistone Abs (sensitive for drug-induced lupus) 5. Anticardiolipin Abs 6. decresed C3, C4 and CH50 due to immune complex formation
Treatment of SLE
-NSAIDs -Steroids -Immunosuppressants -Hydroxychloroquine
Sarcoidosis is characterized by...
immune-mediated, non-caseating granulomas and elevated ACE levels.
Sarcoidosis is common in...
Sarcoidosis is often asymptomatic except for...
Findings of Sarcoidosis on CXR are...
bilateral hilar adenopathy and reticular opacities.
Sarcoidosis is associated with...
restrictive lung disease (interstitial fibrosis), erythema nodosum, lupus pernio, Bell palsy, epithelioid granulomas (w/ Schaumann and asteroid bodies), uveitis and hypercalcemia.
Hypercalcemia in sarcoidosis is due to...
increased 1alpha-hydroxylase mediated Vit. D activation in macrophages.
Treatment for Sarcoidosis is....
Polymyalgia rhematica symptoms are...
pain/stiffness in shoulders/hips often with fever, malaise and weight loss.
Polymyalgia rheumatica does not cause...
Polymyalgia rheumatica is common in...
women older than 50.
Polymyalgia rheumatica is associated with...
temporal (giant cell) arteritis.
Findings of Polymyalgia rheumatica
-increased ESR -increased CRP -normal CK
Treatment of Polymyalgia rheumatica
Fibromyalgia is most commonly seen in...
females 20-50 yrs old. It is chronic musculoskeletal pain associated with stiffness, paresthesias, poor sleep and fatigue.
-regular exercise -antidepressants -anticonvulsants
progressive, symmetrical proximal muscle weakness characterized by endomysial inflammation with CD8 T cells. Most often involves the shoulders.
similar to polymositis but also has a rash, Gottron papules, heliotrope rash. (shawl and face rash and mechanic's hands)
Dermatomyositis has increased risk of...
-perimysial inflammation and atrophy with CD4 T cells
Findings of Polymyositis and Dermatomyositis
-increased CK -positive ANA -positive anti-Jo-1 -positive anti-SRP -positive anti-Mi-2 Abs
Treatment of Dermatomyositis and Polymyositis
Pathophysiology of Myasthenia gravis
autoantibodies to postsynaptic ACh receptor
Clinical findings of myastenia gravis
ptosis, diplopia, weakness *worsens with muscle use
Myasthenia gravis is associated with...
thymoma and thymic hyperplasia
In myasthenia gravis, AChE inhibitor will...
Pathophysiology of Lambert-Eaton Myasthenic Syndrome
autoantibodies to presynaptic Ca2+ channels leading to decreased ACh release
Lambert-Eaton Clinical Findings
-proximal muscle weakness -autonomic symptoms (dry mouth, impotence) *improves with muscle use
Lambert-Eaton is associated with...
small cell lung cancer.
Myositis Ossificans is...
metaplasia of skeletal muscle to bone following muscular trauma.
excessive fibrosis and collagen deoposition throughout the body. commonly sclerosis of the skin, mainfesting as puffy and taut skin. 75% female.
Most common cause of death in scleroderm is...
-widespread skin involvement -rapid progression -early visceral involvement -associated with anti-Scl-70 Ab (anti-DNA topoisomerase I Ab)
-skin involvement limited to fingers and face -CREST involvement -anit-Centromere Ab
C = Calcinosis R = Raynoaud E = Esophageal dysmotility S = Sclerodactyly T = Telangiectasia
A macule is a...
flat lesion with well-circumscribed chin in skin color
A patch is...
a macule > 1 cm. Ex. large birthmark (congenital nevus)
A papule is...
an elevated, solid skin lesion
A plaque is...
a papule > 1 cm. Ex. Psoriasis
small fluid-containing blister
large fluid containing blister > 1 cm Ex. bullous pemphigoid
vesicle containing pus ex. pustular psoriasis
transient smooth papule or plaque Ex. hives (urticaria)
flaking off of stratum corneum Ex. eczema, psoriasis, SCC
dry exudate Ex. impetigo
increased thickness of the stratum corneum Ex. psoriasis, calluses
hyperkeratosis with retention of nuclei in stratum corneum Ex. psoriasis
epidermal accumulation of edematous fluid in the intercellular spaces Ex. eczematous dermatitis
separation of epidermal cells Ex. pemphigus vulgaris
Epidermal hyperplasia (increased spinosum) Ex. Acanthosis nigricans
normal melanocyte number with decreased melanin production due to decreased tyrosinase activity or defective tyrosine transport (or by failure of neural crest cell migration)
Albinism has an increased risk of...
Melasma (cholasma) is...
hyperpigmentation associated with pregnancy or OCP use
irregular areas of complete depigmentation caused by autoimmune destruction of melanocytes
warts caused by HPV; soft, tan cauliflower-like papules
Histological changes of verrucae
epidermal hyperplasia, hyperkeratosis, koilocytosis
common mole; melanoma can arise in congenital or atypical moles *intradermal nevi are papular **junctional nevi are flat molecules
hives; pruritic wheals that form after mast cell degranulation
Urticaria is characterized by...
superficial dermal edema and lymphatic channel dilation.
freckle; normal number of melanocytes but increased melanin pigment
Atopic dermatitis (eczema)
pruritic eruption commonly on skin flexures; often associated with other atopic diseases (asthma, allergic rhinits)
Atopic dermatitis usually starts on...
the face in infancy and often appears in the antecubital foassae after.
Allergic Contact Dermatitis
Type IV HSR that follows exposure to teh allergen; lesions occur at the site of contact (ex. nickel, poison ivy, neomycin)
papules and plaques with silvery scaling (knees and elbows); acanthosis with parakeratotic scaling increased spinosum, decreased granulosm Auspitz sign
Psoriasis can be associated with...
nail pitting and psoriatic arthritis.
Seborrheic keratosis is...
flat, greasy, pigmented squamous epithelial proliferation with keratin-filled cysts (horn cysts); look "stuck on" *common benign neoplasm of older people
Seborrheic keratosis lesions occur on...
the head, trunk and extremities.
Lese-Trelat sign is...
a sudden appearance of multiple seborrheic keratoses, indicating an underlying malignancy (GI, lymphoid).
superficial skin infection from S. aureus or S. pyogenes very infectious ***honey-colored crusting
Bullous impetigo has...
bullae and is usually due to S. aureus.
acute, painful spreading infxn of the dermis and subcutaneous tissue.
Cellulitis is usually due to...
S. pyogenes or S. aureus.
Cellulitis often starts with...
a break in thes kin from trauma or another infxn.
Necrotizing fasciitis is...
a deeper tissue injury usually from anaerobic bacteria or S. pyogenes.
Necrotizing fasciitis results in....
crepitus from methane and CO2 production. "flesh-eating bacteria"
Necrotizing fasciitis causes...
bullae and a purple color to the skin.
Staphylococcal scalded skin syndrome is due to....
an exotoxin that destroys keratinocyte attachments in the stratum granulosum only.
Staph scalded skin syndrome is characterized by...
fever and erythematous rash with sloughing of the upper layers of the epidermis that heals completely.
Hairy leukoplakia is...
a white, painless plaque on the tongue that cannot be scraped off.
Hairy leukoplakia is mediated by...
EBV and it occurs in HIV + patients.
Pemphigus vulgaris is a...
potentially fatal skin disorder with IgG antibody against desmoglein component of desmosomes. There is flaccid intraepidermal bullae caused by acantholysis; oral mucosa also involved.
Immunofluorescence of Pemphigus vulgaris reveals...
Abs around epidermal cells in a reticular pattern. (net-like)
Pemphigus vulgaris has a positive...
Nikolsky sign (separation of epidermis upon manual stroking of skin).
Bullous Pemphigoid is less severe....
than Pemphigus vulgaris. It involves IgG antibody against hemidesmosomes.
Bullous Pemphigoid shows....
tense blisters containing eosinophils that affect the skin but spare the oral mucosa.
Immunofluorescence of bullous pemphigoid reveals...
a linear pattern at the epidermal-dermal junction.
Bullous pemphigoid has a negative...
pruritic papules, vesicles and bullae. Deposits of IgA at the tips of dermal papillae
Dermatitis herpetiformis is associated with...
Erythema multiforme is associated with....
infections (mycoplasma pneumoniae, HSV) drugs (sulfa drugs, beta-lactams, phenytoin) cancers autoimmune disease
Erythema multiforme presents with...
multiple lesions - macules, papules, veiscles and target lesions.
Stevens-Johnson Syndrome is characterized by...
fever, bulla formation and necrosis, sloughing of skin, and a high mortality rate.
SJS typically involves...
2 mucous membranes (lips and mouth, etc.). Skin lesions appear like targets. Associated with drug rxn.
A more severe form of SJS is...
toxic epidermal necrolysis with more than 30% of the body involved.
Acanthosis nigricans is...
epidermal hyperplasia causing symmetrical, hyperpigmented, velvety thickening of skin, especially on neck or axilla.
Acanthosis nigricans is associated with...
hyperinsulinemia (diabetes, obesity, Cushing's) and visceral malignancy (gastric adenocarcinoma).
Actinic keratosis is....
premalignant lesions caused by sun exposure.
Actinic keratosis presents as...
small, rough, erythematous/brownish papules or plaques.
Risk of SCC with actinic keratosis is proportional to...
the degree of epithelial dysplasia.
Erythema nodosum is...
a painful, inflammatory lesion of subcutaneous fat, usually on anterior shins.
Erythema nodosum is often idiopathic but can be associated with...
sarcoidosis, coccidioidomycosis, histoplasmosis, TB, strep, leprosy and Crohn's.
6 Ps of Lichen Planus
pruritic purple polygonal planar papules plaques
Mucosal involvement with Lichen Planus manifests as...
Wickham striae (reticular white lines). Also sawtooth infiltrate of lymphocytes at the dermal-epidermal junction.
Lichen Planus is associated with...
Pityriasis rosea presents as...
a herald patch followed days later by christmas tree distribution of multiple plaques with collarette scale.
Course of Pityriasis rosea
self-resolving in 6-8 wks.
DNA mutations, inducing apoptosis of keratinocytes.
UVA is dominant in...
tanning and photoagin.
UVB is dominant in...
Sunburn can lead to...
impetigo and skin cancer.
The most common skin cancer is...
basal cell carcinoma. It is found in sun-exposed areas of the body and is locally invasive but rarely metastasizes.
BCC presents with...
pink, pearly nodules, commonly with telangiectasias, rolled borders and central crusting/ulceration.
BCC can also appear as...
nonhealing ulcers with infiltrating growth or as a scaling plaque.
Histology of BCC shows...
Squamous Cell Carcinoma is associated with...
excessive exposure to sunlight, immunosuppression, and arsenic.
SCC commonly appears on...
the face, lower lip, ears and hands. It is locally invasive, can spread to LNs but rarely metastasizes.
SCC appears as...
ulcerative red lesions with frequent scale. And chronic draining sinuses.
Histology of SCC shows...
Melanoma has a significant risk of...
metastasis. Risk correlates with depth of tumor.
Tumor marker of melanoma
Melanoma is associated with...
sunlight exposure, fair-skinned persons are at increased risk.
ABCDEs of Melanoma
A = asymmetry B = border irregularity C = color variation D = diameter > 6 mm E = evolution over time
Melanoma is often driven by ...
an activating mutation of BRAF kinase.
Primary treatment of melanoma is...
excision with appropriately wide margins.
Metastatic or unresectable melanoma in pts with BRAF V600E mutation may benefit from...
vemurafenib, a BRAF kinase inhibitor.