Chapter 25: Skin - Dermatoses, Blistering , Epidermal Appendage, and Infections Flashcards

1
Q

Ichthyosis is a group of inherited disorders that results in what?

A
  • Chronic, excessive keratin buildup (hyperkeratosis) –> fishlike scales
  • Defective desquamation
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2
Q

All forms of ichthyosis exhibit a buildup of what; morphologic appearance?

A

Buildup of compated stratum corneum that is assoc. w/ loss of normal basket-weave pattern

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3
Q

Angioedema is closely related to urticaria and is characterized by what?

A

Edema of the deeper dermis and SQ fat

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4
Q

What are the histologic changes seen in Urticaria?

A
  • Sparse superficial perivenular infiltrate consisting of mononuclear cells
  • Collagen bundles are more widely spaced than in normal skin –> clear spaces in between
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5
Q

Urticaria (hives) is a common disorder of the skin characterized by what?

A
  • Localized mast cell degranulation —> dermal microvascular hyperpermeability
  • Results in pruritic edematous plaques (wheals)
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6
Q

Acute eczematous dermatitis is which type of hypersensitivity?

A

T-cell mediated inflammatory rxn (type IV hypersensitivity)

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7
Q

All types of eczematous dermatitis are characterized by what type of lesions and what occurs if persistent?

A
  • Red, papulovesicular, oozing, and crusted lesions
  • If persistent –> develop reactive acanthosis and hyperkeratosis that produce red scaling plaques
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8
Q

Which edematous finding characterizes acute eczematous dermatitis; how does this differ from urticaria?

A
  • Spongiosa: edema seeps into the intercellular spaces of the epidermis, splaying apart keratinocytes, particularly in stratum spinosum
  • In urticaria the edema is restricted to superficial dermis
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9
Q

In acute eczematous dermatitis, mechanical shearing of intercellular attachment sites (desmosomes) and cell membranes by progressive accumulation of intercellular fluid may result in formation of what?

A

Intraepidermal vesicles

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10
Q

Erythema multiforme is characterized by keratinocyte injury mediated by what?

A

Skin-homing CD8+ cytotoxic T cells

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11
Q

Which severe febrile form of erythema multiforme is often seen in children with lesions involving not only the skin but also the lips and oral mucosa, conjunctiva, uretha, and genital/perianal areas?

A

Stevens-Johnson Syndrome

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12
Q

Which life threatening complication may arise from Steven-Johnson syndrome?

A

Life-threatening sepsis as a result of 2’ infection due to loss of skin integrity

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13
Q

“Targetoid” lesions are characteristic of what?

A

Erythema Multiforme

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14
Q

What is interface dermatitis as it relates to erythema multiforme?

A

Lymphocyte infiltration along dermoepidermal jct, asooc. with degenerating and necrotic keratinocytes

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15
Q

Psoriasis is strongly linked to which HLA gene locus?

A

HLA-C; paricularly HLA-Cw*0602

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16
Q

What is the Koebner phenomenon and what 2 chronic inflammatory dermatoses can it be seen in?

A
  • Induction of lesions in susceptible pt’s by local trauma, starts a self-perpetuating local inflammatory response
  • Seen with Psoriasis and Lichen Planus
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17
Q

Which body regions most often affected in Psoriasis; how do they lesions appear?

A
  • Skin of elbows, knees, scalp, lumbosacral areas, intergluteal cleft, and glans penis
  • Well-demarcated, pink to salmon-colored plaque covered by loosely adherent silver-white scale
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18
Q

What are the nail changes seen in some pt’s with Psoriasis?

A

Yellow-brown discoloration (oil-slick), with pitting, dimpling, separation of the nail plate from underying bed (onycholysis), thickening, and crumbling

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19
Q

What is the characteristic histologic picture of established lesions seen with Psoriasis?

A
  • Marked epidermal thickening (acanthosis)
  • Downward elongation of the rete ridges –> “test tubes in a rack
  • Abundant mitotic figures
  • Stratum granulosum is thinned or absent, and extensive overlying parakeratotic scale seen
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20
Q

Dilated, tortuous blood vessels within dermal papillae of Psoriasis lesions leads to what characteristic sign when scales are lifted from a plaque?

A

Auspitz sign: mult, minute, bleeding points when scale lifted from plaque

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21
Q

Which immune cells form aggregates within spongiotic foci of the superficial epidermis (spongiform pustules) and within the parakeratotic stratum corneum (munro microabscesses) in psoriasis?

A

Neutrophils (PMNs)

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22
Q

Which chronic inflammatory dermatitis classically involves regions with a high density of sebaceous glands such as the scalp, forehead (especially the glabella), external auditory canal, retroauricular area, nasolabial folds, and presternal area?

A

Seborrheic Dermatitis

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23
Q

What is the most common clinical expression of Seborrheic Dermatitis of the scalp?

A

Dandruff

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24
Q

What are the “Six P’s” of lichen planus?

A

Pruritic, Purple, Polygonal, Planar, Papules, and Plaques

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25
Q

Which chronic inflammatory dermatosis is a self-imited disorder of skin and mucosa, resolving spontaneously in 1-2 years?

A

Lichen Planus

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26
Q

Which complication may arise as a result of the chronic mucosal and paramucosal lesions associated with lichen planus?

A

SCC

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27
Q

What is the morphology of the cutaneous lesions of lichen planus and what is a hallmark finding?

A
  • Itchy, violaceous, flat-topped papules that coalesce to form plaques
  • Papules often highlighted by white dots/lines called Wickham striae, created by areas of hypergranulosis; appear lace-like
28
Q

Oral lesions associated with lichen planus appear how?

A

White, reticulated, or net-like areas (lace like)

29
Q

What is the characteristic appearance of the destructive lymphocytic infiltrate at the dermoepidermal interface in lichen planus?

A

Angulated zig-zag contour = “Saw-toothing”

30
Q

What are the colloid or Civatte bodies seen in lichen planus and other chronic dermatoses in which basal keratinocytes are destroyed?

A

Anucleate, necrotic basal cells incorporated into inflammed papillary dermis

31
Q

The lesions of lichen planus bear similarities to erythema multiforme, but differ in what regard?

A
  • Changes of chronicity –> epidermal hyperplasia (acanthosis) +
  • Thickening of the granular cell layer (hypergranulosis) +

- Stratum corneum (hyperkeratosis)

32
Q

Pemphigus is caused by what?

A

IgG autoantibodies against desmogleins 1 and 3

33
Q

Which type of pemphigus is characterized by large moist verrucous (wart-like) vegetating plaques studded with pustules found in the groin, axilla and flexural surfaces?

A

Pemphigus vegetans

34
Q

Paraneoplastic pemphigus is most commonly associated with what malignancy?

A

non-Hodgkin lymphoma

35
Q

What is the most common histologic denominator in all forms of pemphigus?

A

Acantholysis, the dissolution or lysis of the intercellular bridges that connect squamous epithelial cells

36
Q

An immediately supra-basal acantholytic blister with single layer of intact basal cells resembling a “row of tombstones” is characteristic of which type of pemphigus?

A

Pemphigus vulgaris

37
Q

What is a more benign form of pemphigus that is endemic Brazil and has a predilection for the scalp, face, chest, and back?

A

Pemphigus foliaceus

38
Q

Epidermal, acantholytic blisters vs. subepidermal, non-acantholytic blisters describe which disorders?

A
  • Epidermal, acanthylotic blisters = Pemphigus
  • Subepidermal, non-acantholytic blisters = Bullous pemphigoid
39
Q

Who is most often affected by Bullous Pemphigoid; where do these blisters predominantly occur?

A
  • Elderly
  • Inner thighs + flexor surfaces of forearms + axilla + groin and lower abdomen
40
Q

How does the antibody deposition associated with Bullous Pemphigoid appear with direct immunofluorescence staining?

A

Linear deposition along dermoepidermal jct.

41
Q

In Bullous Pemphigoid autoantibodies bind BPAG2, which is a component of what?

A

Hemidesmosomes

42
Q

Which age group and sex is predominantly affected by dermatitis herpetiformis?

A

Males, most often in 3rd and 4th decades

43
Q

Dermatitis herpetiformis is sometimes associated with what GI disease and how can it be treated?

A

Celiac disease; responds to gluten-free diet

44
Q

What is the pathogenesis of dermatitis herpertiformis in pt with Celiac disease?

A

Develop IgA antibodies to gluten; cross-react with reticulin (component of anchoring fibrils of epidermal BM) –> subepidermal blister

45
Q

Describe the lesions of dermatitis herpetiformis and where they are most often seen?

A
  • Bilateral, symmetric and grouped
  • Involving the extensor surfaces, elbows, knees, upper back, and buttocks
46
Q

How can immunofluorescence staining help distinguish dermatitis herpetiformis?

A

Shows discontinous, granular deposits of IgA localizing to tips of dermal papillae

47
Q

Epidermolysis Bullosa are a group of disorders causes by inherited defects in what; leads to what type of lesions and seen at what age?

A

Defects in structural proteins –> blisters at sites of pressure, rubbing or trauma at (or soon after) birth

48
Q

The simplex type (most common) of epidermolysis bullosa results from mutations in what?

A

Genes encoding keratin 14 or keratin 5

49
Q

Where is the blistering seen in the junctional type of epidermolysis bullosa?

A

Subepidermal blister at the level of the lamina lucida** in otherwise histologically **normal skin

50
Q

Most cases of the junctional type of epidermolysis bullosa are due to what defects?

A

Autosomal recessive** defects in a subunit of **laminin

51
Q

Urticaria and subepidermal vesicles assoc. w/ scarring exacerbated by exposure to sunlight is a feature of what?

A

Porphyrias

52
Q

What are the 4 stages seen with Rosacea?

A
  • Flushing
  • Persistent erythema and telangiectasia
  • Pustules and papules
  • Rhinophyma: permanent thickening of nasal skin
53
Q

Pt’s with rosacea have high cutaneous levels of what; how does this play a role in the pathogenesis?

A

Cathelicidin = important mediator of cutaneous innate immune response

54
Q

Panniculitis refers to inflammation of what; what are the 2 distinct forms?

A
  • Inflammation of subQ adipose tissue; preferentially affecting (1) lobules of fat, or (2) the CT separating fat into lobules
  • 2 distinct forms: erythema nodosum and erythema induratum
55
Q

Describe the presentation and course of the lesions associated with erythema nodosum?

A
  • Erythematous plaques and nodules, more readily palpated than seen
  • Over weeks, lesions usually flatten and become bruise-like, no residual scars
56
Q

Occurrence of erythema nodosum is associated with what?

A
  • Infections: β-hemolytic strep; tuberculosis
  • Drugs: sulfonamides, OCP’s
  • SARCOIDOSIS; IBD; certain malignant neoplasms
57
Q

Which type of hypersensitivity is erythema nodosum?

A

Delayed-type (Type IV)

58
Q

Histologic diagnosis of erythma nodosum requires what?

A

Biopsy of deep wedge of tissue to generously sample the subcutis

59
Q

What is the distinct histopathology of the early and late lesions seen with erythema nodosum?

A
  • Early: CT septae = widened by edema, fibrin exudation, and neutrophil infiltration
  • Late: infiltration by lymphocytes, histiocytes, multinucleated giant cells —> septal fibrosis
60
Q

Necrotizing vasculitis of sm-medium arteries and veins in deep dermis and subcutis + granulomatous inflammation w/ zones of caseous necrosis involving the fat lobule is associated with what?

A

Erythema induratum

61
Q

What is the most common type of wart (verruca) and where does it occur on body and how do they appear grossly?

A
  • Verruca vulgaris; frequently the hands (dorsum) and periungual areas
  • Appear as gray-white to tan, flat to convex, small papules w/ rough, pebble-like surface
62
Q

How can molluscum contagiosum be diagnosed clinically?

A

Umbilicated area –> curd-like material onto slide and stain with giemsa showing diagnostic molluscum bodies

63
Q

Impetigo is most often caused by what?

A

S. aureus

64
Q

Pathogenesis of impetigo leading to blister formation is a from a bacterial toxin causing what?

A

Cleavage of desmoglein 1, protein responsible for cell-cell adhesion within uppermost epidermal layers

65
Q

Fungal hyphae of dermatophytes causing tinea can be stained with what and will appear how?

A

Stained with PAS —> bright pink to red hyphae within stratum corneum