Pathoma - 19 (Skin - Part 1)

eliot2014's version from 2016-01-22 03:54

Section 1

Question Answer
What are the 5 layers of the epidermis starting from bottom up?basalis, spinosum, granulosum, lucidum, corneum
which layer of the epidermis: characterized by desmosomes btw keratinocytesstratum spinosum
what is the regenerative stem cell layer of the skin?stratum basails
which layer of epidermis is characterized by GRANULES in keratinocytesstratum granulosum
which layer of epidermis is characterized by keratin in ANUCLEATE cellsstratum corneum
dermis consists ofconnective tissue, nerve endings, blood and lymphatic vessels, and adnexal structures (e.g. hair shafts, sweat glands, and sebaceous glands)

Section 2

Question Answer
What are the two types of dermatoses?atopic (eczematous) dermatitis and contact dermatitis
which type of HSN is eczema (atopic dermatitis)?Type I hypersensitivity
what does atopic (eczematous) dermatitis look like?pruritic, erythematous, oozing rash with vesicles and edema
Where is atopic dermatitis usually located?face and flexor surfaces
What causes atopic dermatitis?it is a type I hypersensitivity reaction associated with exposure to environmental antigens.
What is atopic dermatiis associated with?ashtma and allergic rhinitis.
What does contact dermatitis look like?pruritic, erythematous, oozing rash with vesicles and edema.
What causes contact dermatitis?Caused by exposure to allergens
What allergens commonly cause contact dermatitis?poison ivy and nickel jewelry (type iv hsr); irritant chemicals like detergents; drugs like penicillin
which DRUG can cause CONTACT DERMATITIS?penicillin
another name for whiteheads and blackheadscomedones
another name for pimplespustules
What are nodulesscarred pimples
whats the mechanism of acne? why does it happen?acne is chronic inflammation of hair follicles and sebaceous gland (hormones cause increase in sebum production-->excess keratin production blocks follicles, forming comedones)
What type of receptors do sebaceous glands have?androgen receptors
what bacteria causes acne?propionibacterium acnes
how does propionbacterium acnes causes acne?propionbacterium acnes infection produces LIPASES that break down sebum, releasing PROINFLAMMATORY fatty acids-->results in pustule or nodule formation.
whats the 2 tx for acne?benzoyl peroxide (antimicrobial) and vitamin A derivatives (e.g. isotretinoin)
What is the function of vitamin A (normally) in the body?maintains specialized epithelium like keratin.
What does psoriasis look like?well-circumscribed, salmon-colored plaques with silvery scale
Where is psoriasis usually located?Extensor surfaces and scalp. Pitting of nails may also be present
what is psoriasis due to (describe the pathology)?due to excessive KERATINOCYTE proliferation
which HLA is associated with psoriasis?HLA-C
What may cause psoriatic lesions?trauma (e.g. enviromental trigger)
histology of psoriasisacanthosis, parakeratosis, Munro abscesses, Auspitz sign
what is acanthosis?epidermal hyperplasia
what is parakeratosis?hyperkeratosis with retention of keratinocyte nuclei in stratum corneum
munro abscessescollection of neutrophils in stratum corneum
why is there a postive Auspitiz sign in psoriasis?bc there is THINNING of the epidermis above elongated dermal papillaie-->results in pinpoint bleeding when scale in picked off
pin point bleed when scale is picked off showing dermal papillar blood vesselsAuspitz sign a/w psoriasis
whats the tx of psoriasis?UVA light (which damages keratinocytes) with psoralen (absorbs UVA well); or immune modulating therapy
inflammation of dermal-epidermal jxn with SAW TOOTH appearancelichen planus
saw tooth dermal-epidermal jxnlichen planus
what virus is associated with lichen planushep C
What does lichen planus look like?pruritic, planar, polygonal, purple papules, often with reticular white lines on their surfaces (Wickham striae--usually on oral mucosa).
Where is lichen planus commonly found?wrists, elbows, and oral mucosa

Section 3

Question Answer
what causes pemphigus vulgarisautoimmune destruction of desmosomes btw keratinocytes
what causes pemphigus vulgaris?IgG antibody against desmoglein
What type of hypersensitivity is pemphigus vulgaris?type II
Clinical presentation of pemphigus vulgarisskin and oral mucosa bullae
What causes a tomb stone appearance?basal layer cells remain attached to BM via hemidesmosomes = pemphigus vulgaris
what layer is disrupted in pemphigus vulgaris?stratum spinosum = keratinocytes are connected by desmosomes-->the separation causes suprabasal blisters
nikolsky sign positivepemphigus vulagris = thin walled bullae rupture easily-->causes shallow erosions with a dry crust
IF shows IgG surrounding keratinocytes in "fish net" patternpemphigus vulagris
fish net immunofluorescencepemphigus vulgaris
where is the blister located in pemphigus vulgaris?blister btw BASAL LAYER and rest of epidermis
autoimmune destruction of hemidesomosomes between basal cellsbullous pemphigoid
blistering dermatosis with IgG autoantibody against hemidesmosome of BM collagenbullous pemphigoid
Which component of the hemidesmosome do IgG antibodies target in bullous pemphigoid?BP180
between what layers is the blister located in bullous pemphigoidblister is btw dermis and epidermis
negative nikolsky signbullous pemphigous
What part of the body is spared in bullous pemphigoid?oral mucosa
IF highlights IgG along basement membrane (linear pattern)bullous pemphigous
pathology of dermatitis herpetiformis?autoimmune deposition of IgA at the tips of dermal papillae
how does dermatitis herpetiformis present clinically?pruritic vesicles and bullae that are grouped (herpetiform)
What autoimmune disorder is dermatitis herpetiformis associated with?celiac disease. DH resolves after pts switch to a gluten free diet
what is erythema multiforme and what is it characterized by on the skin?hypersensitivity reaction characterized by targetoid rash and BULLAE
Why is the rash of erythema multiforme targetoid?due to central epidermal necrosis surrounded by erythema
what virus causes erythema multiforme (not to be confused with erythema chronicus migrans)? bacterial cause?HSV (most common) Mycoplasma
What are non-infectious causes of erythema multiforme?drugs (penicillin, sulfonamides), autoimmune disease like SLE, Malignancy
which autoimmune disease can cause erythema multiforme?SLE
erythema multiforme + oral mucosa/lip involvement + feversteven johnsons syndrome
severe form of steven johnsons syndrometoxic epidermal necrolysis = diffuse sloughing of skin, resembling large burn
What is the most common cause of toxic epidermal necrolysis?adverse drug reaction

Section 4

Question Answer
epithelial tumor that shows benign squamous proliferationseborrheic keratosis
coin-like waxy stuck on appearanceseborrheic keratosis = benign squamous proliferation
most common location of seborrheic keratosisextremitis or face
histology shows keratin pseudocystsseborrheic keratosis
what is leser trelat sign?explosion of seborrheic keratoses!
whats is leser trelat due to?underlying carcinoma of GI tract
what malignancy is associated with acanthosis nigricans?gastric carcinoma
what condition (non-malignant) is associated with acanthosis nigricans?insulin resistance (e.g. non-insulin-dependent diabetes)
What is acanthosis nigricans?epidermal hyperplasia with darkening of the skin. Often involves axilla or groin.
What is the most common cutaneous malignancy?basal cell carcinoma
Risk factors for BCC?UVB-induced DNA damage and prolonged exposure to sunlight, albinism, and xeroderma pigmentosum
upper lip shows elevated nodule with central ulcerated crater surrounded by dilated (telangiectatic) vesselsbasal cell carcinoma
pink pearly papulebasal cell carcinoma
What does BCC look like on histology?nodules of basal cells with peripheral palisading
whats the classic location for basal cell carcinoma?UPPER lip
if you have a pt who receives a transplant and you pt them on immunosuppressants, what is the most common carcinoma that they will develop?squamous cell carcinoma
risk factors a/w squamous cell carcinomaimmunosuppressive therapy, arsenic exposure, scar from burn or draining sinus tract, UVB-induced DNA damage and prolonged sun exposure, albinism, xeroderma pigmentosum
epithelial tumor involving LOWER lipsquamous cell carcinoma
whats the precursor lesion of squamous cell carcinoma?actinic keratosis
Where does actinic keratosis usually present?face, back, or neck
Hyperkeratotic, scaly plaqueactinic keratosis
cup-shaped tumor filled with keratin debriskeratoacanthoma = squamous cell carcinoma that develops rapidly and regresses spontaneously

Section 5

Question Answer
What layer are melanocytes located?basal layer of epidermis
Where is melanin made?in melanosomes
From what germ layer are melanocytes derived?neural crest
What is the precursor molecule for melanin?Tyrosine
Melaonsomes pass melanin to which cells?keratinocytes
autoimmune destruction of melanocytes?vitiligo

Section 6