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

Question 1

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

Answer 1

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

Question 2

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

Answer 2

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

Question 3

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

Answer 3

Edema of the deeper dermis and SQ fat

Question 4

What are the histologic changes seen in Urticaria?

Answer 4

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

Question 5

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

Answer 5

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

Question 6

Acute eczematous dermatitis is which type of hypersensitivity?

Answer 6

T-cell mediated inflammatory rxn (type IV hypersensitivity)

Question 7

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

Answer 7

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

Question 8

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

Answer 8

• 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

Question 9

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?

Answer 9

Intraepidermal vesicles

Question 10

Erythema multiforme is characterized by keratinocyte injury mediated by what?

Answer 10

Skin-homing CD8+ cytotoxic T cells

Question 11

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?

Answer 11

Stevens-Johnson Syndrome

Question 12

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

Answer 12

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

Question 13

“Targetoid” lesions are characteristic of what?

Answer 13

Erythema Multiforme

Question 14

What is interface dermatitis as it relates to erythema multiforme?

Answer 14

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

Question 15

Psoriasis is strongly linked to which HLA gene locus?

Answer 15

HLA-C; paricularly HLA-Cw*0602

Question 16

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

Answer 16

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

Question 17

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

Answer 17

• 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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

• 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

Question 20

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

Answer 20

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

Question 21

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

Answer 21

Neutrophils (PMNs)

Question 22

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?

Answer 22

Seborrheic Dermatitis

Question 23

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

Answer 23

Dandruff

Question 24

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

Answer 24

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

Question 25

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

Answer 25

Lichen Planus

Question 26

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

Answer 26

**SCC**

Question 27

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

Answer 27

- **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**

Question 28

Oral lesions associated with lichen planus appear how?

Answer 28

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

Question 29

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

Answer 29

**Angulated zig-zag contour = "Saw-toothing"**

Question 30

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

Answer 30

**Anucleate**, _necrotic_ **basal cells** incorporated into inflammed papillary dermis

Question 31

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

Answer 31

- Changes of _chronicity_ --\> **epidermal hyperplasia _(acanthosis)_** + - _Thickening_ of the **granular cell layer (_hypergranulosis_****_)_** + **- Stratum corneum** **(_hyperkeratosis_)**

Question 32

Pemphigus is caused by what?

Answer 32

**IgG autoantibodies** _against_ **desmogleins 1** and **3**

Question 33

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?

Answer 33

Pemphigus **vegetans**

Question 34

Paraneoplastic pemphigus is most commonly associated with what malignancy?

Answer 34

**non-Hodgkin lymphoma**

Question 35

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

Answer 35

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

Question 36

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?

Answer 36

Pemphigus **vulgaris**

Question 37

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

Answer 37

Pemphigus **foliaceus**

Question 38

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

Answer 38

- ****_Epi_**dermal, acanthylotic** blisters = **Pemphigus** - ****_Sub_**epidermal**, **_non_**-**acantholytic** blisters = **Bullous pemphigoid**

Question 39

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

Answer 39

- **Elderly** - **Inner thighs** + **_flexor_** surfaces of **forearms + axilla + groin** and **lower abdomen**

Question 40

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

Answer 40

**_Linear_ deposition** along **dermoepidermal jct.**

Question 41

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

Answer 41

**Hemidesmosomes**

Question 42

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

Answer 42

**Males**, most often in **3rd** and **4th** **decades**

Question 43

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

Answer 43

**Celiac disease**; responds to **gluten-free diet**

Question 44

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

Answer 44

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

Question 45

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

Answer 45

- **Bilateral**, **symmetric** and **grouped** - Involving the **_extensor_** surfaces, **elbows**, **knees**, **upper back**, and **buttocks**

Question 46

How can immunofluorescence staining help distinguish dermatitis herpetiformis?

Answer 46

Shows discontinous, **granular deposits** of **IgA** _localizing_ to **tips of dermal papillae**

Question 47

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

Answer 47

Defects in _structural proteins_ --\> **blisters** at sites of **pressure, rubbing** or **trauma** at (or soon after) birth

Question 48

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

Answer 48

Genes encoding **keratin 14** or **keratin 5**

Question 49

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

Answer 49

**_Subepidermal_** **blister** at the level of the **_lamina lucida**_ in otherwise histologically _**normal_** skin

Question 50

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

Answer 50

Autosomal **_recessive**_ defects in a subunit of _**laminin_**

Question 51

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

Answer 51

Porphyrias

Question 52

What are the 4 stages seen with Rosacea?

Answer 52

- **Flushing** - **Persistent erythema** and **telangiectasia** - **Pustules** and **papules** - **Rhinophyma**: permanent thickening of nasal skin

Question 53

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

Answer 53

**Cathelicidin** = important _mediator_ of cutaneous **innate immune response**

Question 54

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

Answer 54

- 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

Question 55

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

Answer 55

- Erythematous _plaques_ and _nodules_, more readily **palpated** than seen - Over weeks, lesions usually _flatten_ and become **bruise-like**, _no_ residual scars

Question 56

Occurrence of erythema nodosum is associated with what?

Answer 56

- **Infections**: β-hemolytic strep; tuberculosis - **Drugs**: sulfonamides, OCP's - **SARCOIDOSIS; IBD**; certain **malignant** neoplasms

Question 57

Which type of hypersensitivity is erythema nodosum?

Answer 57

**Delayed-type** (**Type IV**)

Question 58

Histologic diagnosis of erythma nodosum requires what?

Answer 58

**Biopsy** of _deep_ wedge of tissue to generously sample the **subcutis**

Question 59

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

Answer 59

- **Early**: CT septae = _widened_ by **edema**, **fibrin exudation**, and **neutrophil** infiltration - **Late**: infiltration by **lymphocytes**, **histiocytes**, **multinucleated giant cells** ---\> _septal fibrosis_

Question 60

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?

Answer 60

Erythema induratum

Question 61

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

Answer 61

- **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**

Question 62

How can molluscum contagiosum be diagnosed clinically?

Answer 62

**Umbilicated area** --\> _curd-like material_ onto slide and stain with **giemsa** showing diagnostic **molluscum bodies**

Question 63

Impetigo is most often caused by what?

Answer 63

***S. aureus***

Question 64

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

Answer 64

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

Question 65

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

Answer 65

Stained with **PAS** ---\> **bright pink** to **red** _hyphae_ within **stratum corneum**