CLIN PATH I: EXAM #2 (DERM 2.0)

Functions of skin:

1. maintain body temp

2. protection

3. receive external stimuli

4. control insensible water loss (why burn victims lose a lot of water)

Skin is distinct from mucosa in that it contains:

adnexal structures (ex. eccrine units for sweat and folliculosebaceous units for hair/oil)

Two important skin layers

a stratified squamous epithelium, the epidermis

and a layer of connective tissue, the dermis

Epidermis

superficial layer (thick, protective)

**have keratinocytes, melanocytes, and is where the eccrine sweat glands open

Dermal layer

epidermal junction (undulating basement membrane)

Dermis layer

semi-fluid, which binds the body together

**contains nerve endings, sweat glands, har follicles, blood/lymph vessels

Where do tattoos go?

dermis

What is found in the granular layer?

cells with cytoplasmic granularity (from an accumulation of keratin and structural proteins)

What is found in the spinous layer?

cells with ample cytoplasm and prominent desmosomes

What serves as the foundation in the basal layer?

cuboidal germinative keratinocytes

When your skin grows, ________ layers are on top

older

Dendritic cells that are intercalated among the keratinocytes of the epidermis

Melanocytes and Langerhans cells

Melanocytes are positioned in the ___________ and synthesize ____________

basal layer; melanin (reddish-brown biochrome to protect against UV rays)

Langerhans cells are positioned in the ___________ and are ____________

midspinous layer; antigen-presenting cells

What serves as the scaffolding that supports neurovascular networks?

dermis

If skin loses elasticity, it is the __________ layer

dermis

**composed of collagen (type I and III and elastic microfibrils)

What are ubiquitous in the dermis layer?

fibrocytes (also mast cells and dendritic immune cells)

Three types of skin diseases:

inflammatory

infectious

neoplastic

Macule

increased or decrease pigmentation

<1 cm

non-palpable and superficial

Patch

macular lesions

circumscribed

> 1 cm

Papule

solid and superficial lesion

< 0.5 cm

often in clusters

can accompany rashes

Etiology of papules

inflammation (infected skin)

accumulated secretions

infection (disseminated histoplasmosis)

hypertrophy of skin

acne

Plaque

plateau elevation w/ SA > height

forms by confluence of papules

> 1 cm

Lichenification

surface is rough & thickened and accentuation of normal skin lines

**plaque

Plaques are often associated with:

pruritic disorders (chronic eczema or atopic dermatitis)

Vesicle

fluid-filled lesions

<1 cm

Bulla

collection of free fluid

> 1 cm

Pustule

vesicle or bulla w/ purulent fluid

superficial

Blisters

bulla or vesicle

defense mechanism (when epidermis separates from dermis, lymph and body fluids collect while the skin regrows)

Etiology of blisteral

chemical or allergic rxn

physical injury (heat, friction, frostbite)

Nodule

solid lesion

> 1cm

epidermis and lower dermis

Wheal

rounded and edematous

well demarcated

no epidermal involvement

A wheal is an:

allergic response to allergens (such as drugs or insect bites)

How can you reproduce a wheal?

Darier's sign

Dermatographism

Darier's sign

gentle rubbing of lesions (followed by local itching and erythema)

Dermatographism

writing on the skin

Cyst

lesion w/ fluid or semi-solid material

elevated and palpable

enclosed sac w/

membranous lining

Abscess

collection of pus

Crusts

dried serum or exudates

Blood appears _______ as a crust

brown

Serum appears ________ as a crust

honey colored (impetigo)

Pus appears _______ as a crust

yellow/green

When are crusts present?

after blisters rupture

Scales (desquamation)

abnormal areas of stratum corneum (increased rate of epidermal cell proliferation)

**sheet-like, adherent or loose

Erosion

loss of epidermis - heals without a scar

Ulcer

loss of epidermis and dermis

heals with a scar

Telangiectasias

small enlarged blood vessels near skin surface

**often a sign of alcholism

Petechiae

small red/purple spot

<3 mm

Etiology of petechiae

minor hemorrhage (capillary)

thrombocytopenia

decreases platelet function

Purpura

larger red/purple discoloration

3mm-10mm

Etiology of purpura

bleeding under skin

Ecchymosis

capillary damage allows blood to extravasate into surrounding tissues

>1 cm

Etiology of Ecchymosis

usually blunt trauma

Will petechiae, purpura, and ecchymosis blanch with pressure?

no

Tumor

solid lesion with elevation and depth (epidermis and dermis - possible SC tissue)

> 2 cm

pigmentation

Common serpiginous lesion

hookworm

What will move deeper into the skin (past superficial layer)

nodula

bulla

pustule

fissure

Perivascular dermatitis

inflammatory infiltrate with no significant epidermal involvement

ex. hives

Spongiotic dermatitis

intercellular epidermal edema (spongiosis)

ex. allergic contact dermatitis

Psoriasiform dermatitis

epidermal thickening from elongated rete ridges

ex. psoriasis

Interface dermatitis

cytotoxic rxn (dermis and epidermis)

characterized by vacuoles and lymphocyte infiltrates

ex. lichen planus

Vesiculobollous dermatitis

intradermal and subepidermal cleavage

ex. bullous pemphigoid

Vasculitis

damage to cutaneous vessel walls

ex. leukocytoclastic vasculitis

Folliculitis

rxn directed against colliculo-sebaceous units

ex. acne folliculitis

Nodular dermatitis

nodular or diffuse dermal infiltrate without significant epidermal changes

ex. cutaneous sarcoidosis

Panniculitis

involves subcutaneous fat

ex. erythema nodosum

Psoriasis clinical presentation

common chronic, persistent or relapsing, scaling skin

sharply marginated and erythematous w/ silvery scales

Psoriasis pattern

psoriasform dermatitis

Epidemiology of psoriasis

3rd decade - most common

genetic factors

Psoriasis is characterized by:

epidermal hyperplasia

elongation of rete ridges (as well as clubbing, fusing, and thickening)

thinning of suprapapillary plate

Parakeratotic hyperkeratosis

Migration of neutrophils from the dermal papillae into the overlying epidermis

Squirting dermal papillae (occurs in psoriasis)

Where does psoriasis occur?

scalp, extensor surfaces, flexural surfaces, nail bed

What is spared in psoriasis

mucosal surfaces

Psoriatic arthritis

extracutaneous manifestation of psoriasis - derforming, asymmetric oligoarticular arthritis

Psoriatic arthritis is classified as:

seronegative spondyloarthropathy

What is an inflammatory skin disease in which the junction between the papillary dermis and epidermis is obscured?

interface dermatitis

During interface dermatitis, lymphocytes attack the basal layer of the epidermis causing:

vascular change in basal cells or necrosis of basal keratinocytes

Acute interface dermatitis

erythema multiforme

Pathophysiology of interface dermatitis

T-cell mediated damage to keratinocytes and remodeling of the basement membrane zone

**injury produces vacuoles alone dermoepidermal junction

Lichen planus epidermiology

adulthood

more common in women

**can be caused by drugs, but etiology is mostly unknown

Pathogenesis of lichen planus

dense infiltrate of T lymphocytes in the papillary dermis and superficial dermis; then vacuoles appear in the lower epidermis

**damages keratinocytes and melanocytes

Mature lichen planus lesions are composed of:

CD8 and cytotoxic T cells

Physical exam - Lichen planus

pruritic eruption of small papules (bilateral and symmetrical) w/ angular borders

violaceous in color

solitary lesions coalesce to form larger plaques

Wickham's striae

Wickham's striae

minute white streaks on lesion surfaces

Common sites of lichen planus

flexor surfaces

genital skin

mucous membranes

Erythema multiforme

uncommon

peaks in 2nd to 4th decade

What is Erythema multiforme

cell mediated immune reaction that results in necrosis of epidermal keratinocytes

Etiology of Erythema multiforme

HSV infection

Rxn to meds

Idiopathic

Physical exam of Erythema multiforme

brief and self-limited

in crops of acral surfaces (distal portions of limbs)

prototypical lesion (monomorphous) - target-like

Pathogenesis of Erythema multiforme

keratinocyte necrosis and CD4/CD8 infiltrate

Mild cases of keratinocyte necrosis have been triggered by:

HSV

EM minor

scattered lesions w/ limited mucosal involvement

EM major

prominent involvement of 2-3 mucosal sites (oral, anogenital, conjunctival)

Examples of EM major

Steven-Johnson Syndrome

Toxic epidermal necrolysis (caused by a drug rxn)

Bullous Pemphigoid (vesiculobolous dermatitis pattern)

blistering disease in which tense fluid-filled spaces develop within erythematous, inflamed skin

**detachment of the epidermis from the dermis

Pemphigus vs. Pemphigoid

intraepidermal rather than subepidermal vesiculation

**pemphigus is deeper

Bullous Pemphigoid - Epidemiology

elderly

Bullous Pemphigoid - etiology

Immunoglobulins and complement are deposited along the epidermal-dermal junction in bullous pemphigoid --> form of autoimmune disease

Subepidermal cleft contains:

eosinophils and lymphocytes

Clinical manifestations of Bullous Pemphigoid

present w/ large tense blisters (extremities and lower trunk)

**often associated w/ pruritis