Skin Pathology (Non-pigmented Lesions) Flashcards
(42 cards)
1
Q
What is the skin?
A
- a barrier against environmental insults and fluid loss.
2
Q
What are the 2 main layers of the skin?
A
- epidermis = keratinocytes
- dermis= connective tissue, nerve endings, blood vessels, lymphatic vessels, and adnexal structures (hair shafts, sweat glands, and sebaceous glands).
3
Q
What are the 4 layers of the epidermis?
A
- Stratum basalis
- Stratum spinosum
- Stratum granulosum
- Stratum corneum
4
Q
What layer of the epidermis is the regenerative stem cell layer?
A
- Stratum BASILIS
5
Q
What characterizes the stratum spinosum?
A
- DESMOSOMES between keratinocytes
6
Q
What characterizes the stratum GRANULOSUM?
A
- granules in keratinocytes
7
Q
What characterizes the stratum corneum?
A
- keratin in ANUCLEATE cells.
8
Q
What is Atopic Dermatitis (Eczema)?
A
- pruritic, erythematous, oozing rash with vesicles and edema; often involves the face and flexor surfaces.
- TYPE I hypersensitivity reaction associated with asthma and allergic rhinitis.
9
Q
What is Contact Dermatitis?
A
- pruritic, erythematous, oozing rash with vesicles and edema that arises upon exposure to ALLERGENS.
10
Q
What allergens commonly cause contact dermatitis?
A
- poison ivy and nickel jewelry= TYPE IV hypersensitivity.
- irritant chemicals (ex. detergents).
- drugs (ex. penicillin)
11
Q
How do you treat contact dermatitis?
A
- remove the offending agent and topical glucocorticoids.
12
Q
What is Acne Vulgaris?
A
- comedomes (whiteheads and blackheads), pustules (pimples), and nodules (from scarring) due to chronic inflammation of hair follicles and associated sebaceous glands.
- extremely common, especially in adolescents.
13
Q
What is the pathogenesis of acne vulgaris?
A
- hormone-related increase in sebum production (sebaceous glands have androgen receptors) and excess keratin production block follicles, forming comedomes.
14
Q
What bacteria causes acne vulgaris?
A
- PROPIONIBACTERIUM ACNES, which produces LIPASES that break down sebum, releasing proinflammatory fatty acids, which results in pustule or nodule formation.
15
Q
How do you treat acne vulgaris?
A
- benzyol peroxide (antimicrobial).
- vitamin A derivatives (isotretinoin), which reduces keratin production.
16
Q
*** What is Psoriasis?
A
- well-circumscribed salmon-colored plaques with SILVERY SCALE, due to excessive keratin proliferation (possibly autoimmune).
- usually on extensor surfaces and scalp.
- may see pitting of nails.
17
Q
With what is psoriasis associated?
A
- HLA-C
- areas of trauma (environmental triggers).
18
Q
*** What histology will you see with psoriasis?
A
- ACANTHOSIS (epidermal hyperplasia)
- PARAKERATOSIS (hyperkeratosis with retention of keratinocyte nuclei in the stratum corneum).
- collections of neutrophils in the stratum corneum (MUNRO ABSCESSES).
- thinning of the epidermis above elongated dermal papillae; results in bleeding when scale is picked off (AUSPITZ SIGN).
19
Q
How do you treat psoriasis?
A
- corticosteroids
- UV light with psoralen
- immune modulating therapy
20
Q
** What is Lichen Planus? (5 Ps)
A
- Pruritic, Planar, Polygonal, Purple Papules, often with reticular white lines on surface (WICKHAM STRIAE).
- commonly involves wrists, elbows, and oral mucosa.
21
Q
*** What histology will you see with lichen planus?
A
- inflammation of the dermal-epidermal junction with a SAW-TOOTH appearance.
22
Q
With what is lichen planus associated?
A
- chronic hepatitis C virus
23
Q
What is a blister?
A
- space or bubble within the skin
24
Q
What is Pemphigus Vulgaris?
A
- autoimmune destruction of desmosomes (Dsg1 and Dsg3) between keratinocytes due to IgG antibody against DESMOGLEIN (TYPE II hypersensitivity).
- often seen in areas where skin rubs against skin.
25
How does Pemphigus Vulgaris present?
As SKIN and ORAL bullae (blister):
- ACANTHOLYSIS (separation) of the stratum spinosum keratinocytes (normally connected by desmosomes) results in SUPRAbasal blisters.
- basal layer cells remain attached to basement membrane via hemidesmosomes (TOMBSTONE appearance).
- thin-walled bullae rupture easily (NIKOLSKY SIGN), leading to shallow erosions with dried crust.
26
What will immunofluorescence show in pemphigus vulgaris?
- IgG surrounding keratinocytes in a FISH NET pattern.
27
*** What is Bullous Pemphigoid?
- autoimmune (IgG antibody) destruction of hemidesmosomes (BP180) between basal cells and the underlying basement membrane; where bullous pemphigoid antigen 2 (BPAG2) is located.
28
How does bullous pemphigoid present?
- as SUB-EPIDERMAL blisters of the skin, usually in the elderly.
- tense bullae do not rupture easily.
* oral mucosa is SPARED.
29
What will immunofluorescence show in bullous pemphigoid?
- IgG along basement membrane (LINEAR pattern).
30
**** What is Dermatitis Herpetiformis?
- autoimmune deposition of IgA at the tips of dermal papillae.
* strong association with CELIAC DISEASE and resolves with gluten-free diet.
31
*** How does Dermatitis Herpetiformis present?
- as pruritic vesicles and bullae that are grouped (herpetiform).
32
**** What is Erythema Multiforme?
- hypersensitivity reaction characterized by TARGETOID RASH (due to central epidermal necrosis surrounded by erythema) and bullae.
* Most commonly associated with HERPES SIMPLEX VIRUS infection
33
** Besides HSV, with what else is erythema multiforme associated?
- Mycoplasma, drugs (penicillin and sulfonamides), autoimmune disease (SLE) and malignancy.
34
*** What is erythema muliforme with oral mucosa/lip involvement and fever termed?
- Stevens-Johnson syndrome (SJS)
35
*** What is toxic epidermal necrolysis (TEN)?
- a severe form of SJS characterized by diffuse sloughing of skin, resembling a large burn
* most often due to an adverse drug reaction
36
What is Pemphigus vegetans?
- rare, large, moist, verucous plaques.
- pustules also present on the goirn, axillae, adn flexural surfaces.
- Acantholysis (cells above the basal cell layer)
37
What is Pemphigus foliaceus?
- more benign form of pemphigus, endemic to Brazil.
- involves scalp, face, chest, and back
- no mucous membrane involvement.
- acantholysis forms a LEAF-LIKE blister in the superficial epidermis because the autoantibodies are directed against the DSG1 ALONE.
38
What is Pemphigus erythematosus?
- localized less severe form of pemphigus foliaceus.
| - may selectively involve the MALAR AREA of the FACE in a LUPUS LIKE fashion.
39
What is Paraneoplastic pemphigus?
- occurs in association with lymphoid malignancies.
- most common is NON-HODGKIN LYMPHOMA
- caused by autoantibodies that recognize desmogleins.
40
What is Epidermolysis bullosa?
- inherited defects in structural proteins that give stability to the skin.
- tend to form blisters at sites of rubbing, pressure, or trauma.
41
What are the 3 types of Epidermolysis bullosa?
1. Simplex= defects in basal cell layer from mutations in genes encoding KERATIN 14 and 15.
2. Junctional= blisters occur in otherwise normal skin at the level of the LAMINA DENSA.
3. Dystrophic= blisters develop under the lamina densa resulting from mutations in the COL7A1 gene, which encodes for type VII collagen.
42
What is Porphyria?
- inborn or acquired disturbances in porphyrin metabolism (pigments present in hemoglobin, myoglobin, and cytochromes).
- leads to urticaria, SUBepidermal vesicles that heal with scarring, and are EXACERBATED by SUNLIGHT.
