CH19 - Skin Pathology Flashcards Preview

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Flashcards in CH19 - Skin Pathology Deck (143):
1

What is the function of skin?

It is a barrier against environmental insults and fluid loss

2

What is skin composed of?

an epidermis and dermis

3

What is the epidermis comprised of?

keratinocytes and has four layers

4

What are the layers of the epidermis?

1) Stratum basalis 2) Stratum spinosum 3) Stratum granulosum 4) Stratum corneum

5

What is the stratum basalis?

regenerative (stem cell) layer

6

What is the stratum spinosum?

Its characterized by desmosomes between keratinocytes

7

What is the stratum granulosum?

It is characterized by granules in keratinocytes

8

What is the stratum corneum?

It is characterized by keratin in anucleate cells

9

What does the dermis consist of?

connective tissue, nerve endings, blood and lymphatic vessels, and adnexal structures (e.g., hair shafts, sweat glands, and sebaceous glands)

10

What are the inflammatory dermatoses?

1) atopic (eczematous) dermatitis 2) contact dermatitis 3) acne vulgaris 4) psoriasis 5) Lichen Planus

11

What is atopic (eczematous) dermatitis?

Pruritic, erythematous, oozing rash with vesicles and edema; often involves the face and flexor surfaces

12

What are flexor surfaces?

Elbow, wrists and knees

13

What is type 1 hypersensitivity reaction associated with?

asthma and allergic rhinitis

14

What is contact dermatitis?

Pruritic, erythematous, oozing rash with vesicles and edema

15

When does contact dermatitis arise?

upon exposure to allergens

16

What are the allergens for contact dermatitis?

1) Poison ivy and nickel jewelry (type IV hypersensitivity) 2) Irritant chemicals (e.g., detergents) 3) Drugs (e.g., penicillin)

17

What is the treatment for contact dermatitis?

It involves removal of the offending agent and topical glucocorticoids, if needed.

18

What is acne vulgaris?

Comedones (whiteheads and blackheads), pustules (pimples), and nodules; extremely common, especially in adolescents

19

What is acne vulgaris due to?

chronic inflammation of hair follicles and associated sebaceous glands

20

In acne vulgaris, how are comedones formed?

There is hormone-associated increase in sebum production (sebaceous glands have androgen receptors) and excess keratin production block follicles

21

What are propionibacterium acnes?

It is infection that produces lipases that break down sebum, releasing proinflammatory fatty acids; results in pustule or nodule formation

22

What is the treatment for acne vulgaris?

Treatment includes benzoyl peroxide (antimicrobial) and vitamin A derivatives (e.g., isotretinoin), which reduce keratin production.

23

What is psoriasis?

Well-circumscribed, salmon-colored plaques with silvery scale, usually on extensor surfaces and the scalp; pitting of nails may also be present.

24

What is psoriasis due to?

excessive keratinocyte proliferation

25

What is the etiology for psoriasis?

Possible autoimmune etiology

26

What is psoriasis associated with?

HLA-C

27

For psoriasis, what happens if there is an environmental trigger?

lesions often arise in areas of trauma (environmental trigger)

28

What does the histology for psoriasis show?

1) Acanthosis (epidermal hyperplasia) 2) Parakeratosis 3) Collections of neutrophils in the stratum corneum (Munro microabscesses) 4) Thinning of the epidermis above elongated dermal papillae; results in bleeding when scale is picked off (Auspitz sign)

29

What is parakeratosis?

hyperkeratosis with retention of keratinocyte nuclei in the stratum comeum

30

What is the treatment for psoriasis?

it involves corticosteroids, UV light with psoralen, or immune-modulating therapy.

31

What is lichen planus?

Pruritic, planar, polygonal, purple papules often with reticular white lines on their surface (Wickham striae); commonly involves wrists, elbows, and oral mucosa

32

What does lichen planus commonly involve?

Wrists, elbows and oral mucosa

33

What does oral involvement of lichen planus manifest as?

Wickham striae

34

What does histology for lichen planus show?

inflammation of the dermal-epidermal junction with a saw-tooth appearance

35

What is the etiology for lichen planus?

Etiology is unknown

36

What is lichen planus associated with?

chronic hepatitis C virus infection

37

What are the blistering dermatoses?

1) pemphigus vulgaris 2) bullous phemphigoid 3) dermatitis herpetiformois 4) erythema multiforme

38

What is pemphigus vulgaris?

Its autoimmune destruction of desmosomes between keratinocytes

39

What is pemphigus vulgaris due to?

IgG antibody against desmoglein (type II hypersensitivity)

40

What does pemphigus vulgaris present as?

skin and oral mucosa bullae

41

In pemphigus vulgaris, why is there suprabasal blisters?

Acantholysis (separation) of stratum spinosum keratinocytes (normally connected by desmosomes) results in suprabasal blisters.

42

In pemphigus vulgaris, why is there a tombstone appearance?

Basal layer cells remain attached to basement membrane via hemidesmosomes - tombstone appearance

43

In pemphigus vulgaris, why is there shallow erosions with dried crust?

Thin-walled bullae rupture easily (Nikolsky sign), leading to shallow erosions with dried crust.

44

In pemphigus vulgaris, why is there a fish net pattern?

Immunofluorescence highlights IgG surrounding keratinocytes in a fish net pattern.

45

What is bullous pemphigoid?

Autoimmune destruction of hemidesmosomes between basal cells and the underlying basement membrane

46

What is bullous pemphigoid due to?

Its due to IgG antibody against basement membrane collagen

47

What does bullous pemphigoid present as?

blisters of the skin, oral mucosa is spared 1) Basal cell layer is detached from the basement membrane 2) Tense bullae do not rupture easily; clinically milder than pemphigus vulgaris

48

In bullous pemphigoid, what does immunofluorescence show?

it highlights IgG along basement membrane (linear pattern)

49

What is dermatitis herpetiformis?

Autoimmune deposition of IgA at the tips of dermal papillae

50

What does dermatitis herpetiformis present?

as pruritic vesicles and bullae that are grouped (herpetiform)

51

Dermatitis herpetiformis has a strong association with what?

celiac disease; resolves with gluten-free diet

52

What is erythema multiforme?

Hypersensitivity reaction characterized by targetoid rash and bullae

53

What is the targetoid appearance due to?

central epidermal necrosis surrounded by erythema

54

Erythema multiforme is most commonly associated with what?

HSV infection

55

Aside form HSV infections, what do the other associations include?

Mycoplasma infection, drugs (penicillin and sulfonamides), autoimmune disease (eg SLE), and malignancy

56

What is Steven Johnsons syndrome?

EM with oral mucosa/lip involvement and fever is termed Stevens Johnson syndrome (SJS)

57

What is toxic epidermal necrolysis?

It is a severe form of SJS characterized by diffuse sloughing of skin, resembling a large bum; most often due to an adverse drug reaction

58

What are the epithelial tumors?

1) seborrheic keratosis 2) acanthosis nigracans 3) basal cell carcinoma 4) squamous cell carcinoma

59

What is seborrheic keratosis?

Benign squamous proliferation; common tumor in the elderly

60

What does seborrheic keratosis present as?

raised, discolored plaques on the extremities or face; often has a coinlike, waxy, stuck-on appearance

61

What is seborrheic keratosis characterized by?

keratin pseudocysts on histology

62

What is a sign involved with seborrheic keratosis?

Leser-Trelat sign is the sudden onset of multiple seborrheic keratoses and suggests underlying carcinoma of the GI tract

63

What is acanthosis nigricans?

Epidermal hyperplasia with darkening of the skin, velvet-like skin; often involves the axilla or groin

64

What is acanthosis nigricans associated with?

insulin resistance (e.g., non-insulin-dependent diabetes) or malignancy (especially gastric carcinoma)

65

What is basal cell carcinoma?

Malignant proliferation of the basal cells of the epidermis

66

What is the most common cutaneous malignancy?

Basal cell carcinoma

67

What are the risk factors for basal cell carcinoma?

stem from UVB-induced DNA damage and include prolonged exposure to sunlight, albinism, and xeroderma pigmentosum

68

What does basal cell carcinoma present as?

an elevated nodule with a central, ulcerated crater surrounded by dilated (telangiectatic) vessels, pink, pearl-like papule

69

What is the classic location for basal cell carcinoma?

Classic location is the upper lip

70

What does the histology for basal cell carcinoma show?

nodules of basal cells with peripheral palisading

71

What is the treatment for basal cell carcinoma?

surgical excision; metastasis is rare.

72

What is squamous cell carcinoma?

malignant proliferation of squamous cells

73

What is squamous cell carcinoma characterized by?

formation of keratin pearls

74

What are the risk factors for squamous cell carcinoma?

stem from UVB-induced DNA damage and include prolonged exposure to sunlight, albinism, and xeroderma pigmentosum.

75

What are the additional risk factors for squamous cell carcinoma?

they include immunosuppressive therapy, arsenic exposure, and chronic inflammation (eg scar from burn or draining sinus tract)

76

What does squamous cell carcinoma present as?

an ulcerated, nodular mass, usually on the face (classically involving the lower lip)

77

What is the treatment for squamous cell carcinoma?

it is excision; metastasis is uncommon.

78

What is a precursor lesion of squamous cell carcinoma and how does it present?

Actinic keratosis and presents as a hyperkeratotic, scaly plaque, often on the face, back, or neck.

79

What is Keratoacanthoma?

it is well-differentiated squamous cell carcinoma that develops rapidly and regresses spontaneously

80

How does keratoacanthoma present?

as a cup-shaped tumor filled with keratin debris

81

What are the disorders of pigmentation and melanocytes?

1) vitiligo 2) albinism 3) Freckle (ephelis) 4) melasma 5) nevus (mole) 6) melanoma

82

What are melanocytes responsible for?

skin pigmentation

83

Where are melanocytes located?

They are present in the basal layer of the epidermis.

84

What are melanocytes derived from?

the neural crest

85

What do melanocytes do?

Synthesize melanin in melanosomes using tyrosine as a precursor molecule

86

What do melanocytes do?

They pass melanosomes to keratinocytes

87

What is vitiligo?

Localized loss of skin pigmentation

88

What is vitiligo due to?

autoimmune destruction of melanocytes

89

What happens in albinism?

It is a congenital lack of pigmentation

90

What is albinism due to?

an enzyme defect (usually tyrosinase) that impairs melanin production

91

What might albinism involve?

May involve the eyes (ocular form) or both the eyes and skin (oculocutaneous form)

92

What is there an increased risk for in albinism and why?

Increased risk of squamous cell carcinoma, basal cell carcinoma, and melanoma due to reduced protection against UVB

93

What is freckle?

(ephelis) small, tan to brown macule; darkens when exposed to sunlight

94

What is freckle due to?

increased number of melanosomes (melanocytes are not increased)

95

What is melasma?

mask-like hyperpigmentation of the cheeks

96

What is melasma associated with?

pregnancy and oral contraceptives

97

What is nevus?

(mole) benign neoplasm of melanocytes

98

What is congenital nevus?

it is present at birth; often associated with hair

99

When do you see acquired nevus?

it arises later in life.

100

How does a nevus begin?

Begins as nests of melanocytes at the dermal-epidermal junction (junctional nevus);

101

What is the most common mole in children?

nevus

102

What is a compound nevus?

When the nevus grows by extension into the dermis

103

What is an intradermal nevus?

The junctional component is eventually lost resulting in an intradermal nevus, which is the most common mole in adults.

104

What is the most common mole in adults?

Intradermal nevus

105

What is a nevus characterized by?

Characterized by a flat macule or raised papule with symmetry, sharp borders, evenly distributed color, and small diameter (< 6 mm)

106

What might arise from a nevus?

Dysplasia may arise (dysplastic nevus), which is a precursor to melanoma

107

What is melanoma?

Malignant neoplasm of melanocytes; most common cause of death from skin cancer

108

What is the most common form of death from skin cancer?

Melanoma

109

What are the risk factors for melanoma?

They are based on UVB-induced DNA damage and include prolonged exposure to sunlight, albinism, and xeroderma pigmentosum; an additional risk factor is dysplastic nevus syndrome,

110

What is dysplastic nevus syndrome?

autosomal dominant disorder characterized by formation of dysplastic nevi that may progress to melanoma

111

What does dysplastic nevus syndrome present as?

a mole-like growth with ABCD

112

What is the ABCD for a mole like growth in dysplastic nevus syndrome?

1) Asymmetry 2) Borders are irregular. 3) Color is not uniform. 4) Diameter > 6 mm

113

How is melanoma characterized?

by two growth phases

114

What are the growth phases that characterize melanoma?

1) radial growth 2) vertical growth

115

What is the radial growth in melanoma?

It grows horizontally along the epidermis and superficial dermis

116

For radial growth, what is the risk for metastasis?

low risk of metastasis

117

What is the vertical growth in melanoma?

It grows vertically into the deep dermis

118

In vertical growth in melanoma what is the most important prognostic factor in predicting metastasis?

The depth of extension (Breslow thickness) is the most important prognostic factor in predicting metastasis.

119

What are the variants for melanoma?

1) superficial spreading 2) lentigo maligna melanoma 3) nodular 4) acral lentiginous

120

What is superficial spreading in melanoma?

most common subtype; dominant early radial growth results in good prognosis

121

What is the prognosis for superficial spreading in melanoma?

Dominant early radial growth results in good prognosis

122

What is lentigo maligna melanoma and what is the prognosis?

lentiginous proliferation (radial growth) good prognosis

123

What is nodular regarding the variant of melanoma and what is the prognosis?

early vertical growth; poor prognosis

124

What is involved in the Acral lentiginous variant of melanoma?

It arises on the palms or soles, often in dark-skinned individuals; not related to UV light exposure

125

What is impetigo?

Superficial bacterial skin infection

126

What is impetigo most often due to?

S. aureus or S. pyogenes

127

Who does impetigo commonly affect?

children

128

What does impetigo present as?

erythematous macules that progress to pustules, usually on the face; rupture of pustules results in erosions and dry, crusted, honey-colored serum.

129

What is cellulitis?

It?s a deeper (dermal and subcutaneous) infection, usually due to S. aureus or S. pyogenes

130

What does cellulitis present as?

a red, tender, swollen rash with fever

131

What are the risk factors for cellulitis?

They include recent surgery, trauma, or insect bite.

132

What can cellulitis progress to?

Can progress to necrotizing fasciitis with necrosis of subcutaneous tissues due to infection with anaerobic flesh-eating bacteria

133

What happens when cellulitis progresses to necrotizing fasciitis?

1) Production of CO2 leads to crepitus. 2) Surgical emergency

134

What is staphylococcal scaled skin syndrome?

Sloughing of skin with erythematous rash and fever; leads to significant skin loss

135

What is staphylococcal scaled skin syndrome due to?

S. aureus infection; where there is exfoliative A and B toxins that result in epidermolysis of the stratum granulosum.

136

How is staphylococcal scaled skin syndrome distinguished histologically from toxic epidermal necrolysis?

by level of skin separation; separation in TEN (toxic epidermal necrolysis) occurs at the dermal-epidermal junction

137

What is Verruca?

(wart) Flesh-colored papules with a rough surface

138

What is verruca due to?

HPV infection of keratinocytes;

139

What is Verruca characterized by?

koilocytic change

140

What are common locations for verruca?

Hands and feet

141

What is molluscum contagiosum?

Firm, pink, umbilicated papules due to poxvirus;

142

In molluscum contagiosum, what happens to the affected keratinocytes?

it shows cytoplasmic inclusions (molluscum bodies)

143

In whom does molluscum contagiosum most often arise? Who else does it arise?

in children; also occur in sexually active adults and immunocompromised individuals