Name & describe features of the layers of skin: 

epidermis (5), and what lies beneath

Epidermis

Stratum corneum= plate-like keritinocytes

Stratum lucidum = dead, flattened keritinocytes

Stratum granulosum = granular keritinocytes

Stratum spinosum = begininng keritinization

Stratum basale = stem cell layer

Dermis

papillary - terminal capillaries & meissner's

reticular - regularly arranged collagen bundles

Subcutaneous fat

Cause: T-cells enter the skin through blood vessels and cause the top layer of skin, the epidermis, to grow quickly and become thick (in 4 days instead of 1 month).  Genetically determined

Appearance: red pacules evolving into thick "silvery-scaled" plaque

One of a handful of dermatological conditions that is fatal. 

Entire body is red and covered in rash.  Blood is shunted to skin, and can cause hypothermia.  Shedding skin at a furious rate, causing protein and electrolyte depletion.

Histological Features of Psoriasis?

• regular epidermal hyperplasia (psoriasiform)
• thickened granule layer
• hypokeratosis (thin cornea layer)
• parakeratosis (retaining cornea nucleus)
• thinning suprapapillary plate above dermis
• dilated capillary loops
• inflammation in dermal
• "monroe's microabcesses" = pustules

Indicates liklihood of psoratic arthritis. Occurs in ~30-50% of arthritis.

Nail changes called "oil drop sign"

Think 4 P's = pruritis, purple, papule, and polygonal.

Chronic mucocutaneous disease that affects the skin and the oral mucosa, causing 4 P's.  Flat-top (macule) hyperplasia from scratching/irratation

Complicaitions:

anonychia = loss of nail beds

Wickham's striae = whitish lines in papule

associated w/ Hep C

alopecia = loss of hair

squamous cell carcinoma

Inflammation in a band-like fashion hugging the dermal-epidermal junction.  The inflammation and edema damage the adhesion between the 2 layers and can case their separation.

Saw-tooth pattern epidermis seen in lichen planus too (but isn't part of lichenoid infl)

Psoriasis:

UV light exposure

omega 3 FAs (fish)

avoid red meat and alcohol

retinoids, methotrexate, cyclophosphamide

Lichen Planus:

UV light

topical steroids

retinoids

anti-itch cream (topical antihistamine)

Lichen simplex chronicus

Lichen simplex chronicus = skin disorder that involves chronic itching and scratching that causes the appearance of rash.  Occurs in areas that can be reached. Extemely irregular hyperplasia as opposed to regular hyperplase of psoriasis

Benign, self-limited papulosquamous eruption.

• distributes to trunk and scarl regions
• herald patch (2-10cm patch)
• eruptive phase, smaller w/i a few weeks
• trailing scale = colorette scale
• christmas tree distribution

• Perivascular and slightly interstitial infiltrate of lymphocytes (inflammation)
• Edema of the papillary dermis
• Maybe RBC extravasation
• Epidermal hyperplasia
• Prominent spongiosis focally
• Mounds of parakeratosis or scale crust

Used to screen for contact dermatitis (Type IV hypersensitivity).  Place a catch on a patient's back with a battery of chemicals.  If sensitive to a chemical their will be a red rash over contact area

Look for a characteristic pattern of exposure.  The popliteal fossas and antecubital fossas are common sites.

Atopic Dermatis = a recurring Type I hypersensity rxn.  Sensitive to wool.  Rash is completely secondary to scratching.

• molluscum bodies = Large baso & eosinophilic inclusion bodies in cytoplasm of keratinocytes
• invasion of epidermal tissues

Morphology of Molluscum Contagiosum

and treatments

central umbilification (round nodule) on the skin

Tx: make sure adults don't have other STDs

     freeze off lesion, generates irration and body responds

STD = 6 & 11

Wart = 5 & 8

• owl's eyed nucleus (prominent central nucleoulus)
• "chruch spire" epidermal pegs

An infectious disease caused by the yeast Malassezia furfur.  Proliferates in the thickened stratum corneum, superficial infection, causing:

• hypopigmentation
• mealy (dust-like) scaly
• "spaghetti and meatball" appearance under microscope

Caused by a dermatophyte (anamorphic/imprefect funguses), sometimes called "ringworm."  Not the same as Tinea Versicolor.  See characteristic "snake-like" border

Can cause smooth surfaced papules, scaly papules, scaly plaques, nodules, pustules, vesicles, and bullae

Treatment of Tinea vs. Erythrasma

Tinea use Topical or oral antifungals.  Keep area dry.

Erythasma in contrast is a bacterial infection (cornebacterium) and so it requires topical or oral erythromycin

Infectious process caused by the mite Sarcoptes scabiei which burrows into the skin and lays eggs. Produces papules, papulovesicles, papulopustules, and vesicles, some arranged in linear or curvilinear track = borrow.

Do inkblot test on borrow

An immune mediated destruction of epidermis-dermis junction causing multiform lesions. Caused by drugs:

1) penicillins, 2) sulfonamides, and 3) phenytoin

or from infections:

1)HSV 2)Mycoplasma (2 most prominent)

or from vaccinations or malignancy

**Higly suggestive is the "target" lesion (spiraled, layered lesion)

***Can be highly fatal, w/ the sloughing of skin, like burn

This is a premalignant lesion which will show

Epidermal atrophy

Parakeratosis (nuclei in corneum)

Hypogranulosis (an inflam. or neoplastic feature)

Atypical keratinocyte = large nuclues

Keratotic = feels like sand paper

Tx = cryosurgery and sun protection

can use 5-fluoruracil

Benign neoplasm of epidermal keratinocytes

Morpho = "stuck on" appearing hyperpigmented papules or plaques

Never seen in children

"Horned cysts"

Sign Leser-Trelat

Paraneoplastic sign of adenocarcinoma in the stomach, ovary, uterus and breast

• Acanthosis (thickened spinosum)
• Little to no keratinocyte maturation
• Elongated Rete Ridges
• increased nucleus to cytoplasm ratio
• Loss of epidermal polarity
• Intact Epidermal basement membrane = "in situ"
• Breach of epidermal basement mem = invasive

Asymmetry (want symmetrical)

Border (mela has jagged border)

Color (mela has multicolor or really dark brown/black)

Diameter (smaller is better)

Erythema (mela has red border)

Evolution (want mole to be stable overtime)