Dermatology Unit

PA 201: Intro to Medicine

What are the functions of the skin?

Covers the entire body,

Provides protection

Regulates body temperature

Sensory organ

Produces Vitamin D

What is #1?

Epidermis

What is #2?

Papillary Layer

What is #3?

Reticular Layer

What is #4?

Subcutaneous Layer

What is #5?

Dermis

Keratinocyte

produces keratin, a protein in hair, skin, nails

Melanocyte

produces skin pigment melanin when exposed to sunlight, shields against UV radiation, determines skin color

Langerhans Cells

macrophages that initiate immune response, provides defense against environmental foreign proteins

Merkel Cells

touch receptors, found at junction of epidermis and dermis

What is #1?

stratum corneum

What is #2?

stratum lucidum

What is #3?

stratum granulosum

What is #4?

stratum spinosum

What is #5?

stratum basale

Dermis

thickest section of skin,

made of collagen/elastin fibers

rich in blood vessels, lymphatics, sweat glands, sebaceous glands, nerves, has hair follicles

What are the two layers of the dermis?

papillary layer and reticular layer

Papillary layer

directly under epidermis, has capillaries and neurons

Reticular layer

makes up 80% of dermal layer, has collagen bundles, hair follicles, and sweat glands

Subcutaneous

layer of fat/connective tissue with larger blood vessels and nerves

important with regulation of skin/body temp

Lesion

any pathological change in the skin

Primary lesion

develop from previously healthy skin

Secondary lesion

develop from primary lesions

Types of primary skin lesions

macule, patch,

papule, nodule,

tumor, plaque,

vesicle, pustule,

bulla/cyst, wheal,

petechiae/purpura, 

ecchymosis, telangiectasia 

Macule (v)

flat, non-palpable, <2cm

ex. freckles

Macule (p)

Patch (v)

>2cm with color different than surrounding skin

ex. vitiligo, mongolian spot

Patch (p)

Papule (v)

<1cm, raised, palpable

ex. wart (verruca vulgaris)

Papule (p)

Nodule (v)

1-5cm, firm lesion, palpable

ex. mole

Nodule (p)

Tumor (v)

>5cm, solid raised lesion

Tumor (p)

Plaque

>1cm, raised but flat-topped, confluence of papules

ex. psoriasis

Plaque (p)

Vesicle

<1cm, thin-walled, fluid-filled (serum, blood, lymph) lesion

ex. cold sore (herpes simplex)

Vesicle (p)

Bulla (v)

>1cm, fluid-filled lesion

ex. from burns

Bulla (p)

Pustule (v)

raised lesion with purulent exudate

ex. acne, clogged pores

Pustule (p)

Cyst (v)

soft, raised lesion filled with semisolid/liquid material

Cyst (p)

Wheal (v)

raised, flat-topped, transient edematous papule or plaque

ex. urticaria, dermatographia (hive)

Wheal (p)

Petechiae (v)

tiny, circumscribed deposits of blood that don’t blanch (color doesn’t disappear when pressed)

Petechiae (p)

Ecchymosis (v)

larger areas of blood deposits under the skin

ex. bruise

Ecchymosis (p)

Purapura (v)

bleeding disorder producing ecchymosis or petechiae

Purpura (p)

Henoch-Schonlein Purpura (v)

self-limiting hypersensitivity vasculitis with lesions of lower abdomen, butt, legs

Henoch-Schonlein Purpura

Telangiectasia (v)

dilated superficial blood vessels

Telangiectasia (p)

Types of secondary lesions

scales, crusts, ulcer,

erosion, fissure,

excoriations, lichenification,

scar, keloid, atrophy

Scales (v)

dead epidermal cells produced by abnormal keratinization/shedding

Scales (p)

Crusts (v)

collection of dried serum/ cellular debris

ex. scab

Crusts (p)

Ulcer (v)

open lesion of skin/mucus membrane with loss of epidermis and upper papillary layer, usually heals with a scar

ex. aphthous ulcer, decubitus ulcer

Ulcer (p)

Erosion (v)

loss of epidermis, superficial

ex. tinea pedis (athletes’ foot)

Erosion (p)

Fissure (v)

linear ulcer or crack-like lesion

Fissure (p)

Excoriations (v)

linear abrasion of epidermis, self-inflicted by scratching

Excoriations (p)

Lichenification (v)

thickened area of skin from chronic scratching/rubbing

Lichenification (p)

Scar (v)

change in skin from trauma/inflammation

ex. cicatrix, eschar

Scar (p)

Keloid (v)

hypertrophied scars

Keloid (p)

Atrophy (v)

loss of normal skin texture with thinning/wrinkling

Atrophy (p)

8 parts of description/examination of a lesion

quantity- how many

type- primary/secondary

shape- round, oval, irregular, umbilicated (indent), annular (ring-shaped)

color- erythematous, pale, cyanotic, violaceous (purple from blood), brown

arrangement- linear, annular, confluent (merge)

distribution of pattern- generalized (all over), isolated (single/few), localized (many in one spot), intertriginous (in skin folds/rubs), symmetrical, dermatomal (along nerve, on one side only)

margination- well or ill defined

size- measure 

What is the difference between arrangement and distribution of pattern?

arrangement-how lesions are in relation to each other

distribution- where lesions are on the body

Impetigo

most common bacterial infection in children, superficial

caused by Staph aureus or Strep pyogenes

contagious, autoinoculable (spreads), painless

Non- Bullous Impetigo

70% of cases, usually where there was previous skin trauma/disorder

primary- small vesicles/pustules

secondary- rupture/ turn into honey-colored crusts with erythematous base

confluent on nose, cheeks, lips, chin

risk factors- contact sports, poor hygiene, crowded living conditions, hot/humid weather

more contagious, can have mild regional lymphadenopathy

Bullous Impetigo

superficial fragile bullae, rupture/ drain clear-yellow fluid

spreads to face, trunk, extremities, butt (perineal region in infants)

occurs on previously normal skin, not as contagious

Impetigo treatment

localized- topical mupirocin (Bactroban) to affected area TID x 10 days or retapamulin (Altabax)

widespread- oral cephalexin (Keflex) 500mg BID/ 250mg QID (kids dose by weight) or doxycycline (Vibramycin) 100mg BID

Cellulitis

acute, diffuse, spreading infection of dermis/sub-q tissue

caused by Staph aureus or Strep pyogenes

red, hot, tender area of skin, progresses over time

can occur at any age, most often elderly, concerning in diabetics

symptoms- pain in area, fever, chills (all progressive), watch for septicemia

Cellulitis Treatment

Systemic antibiotics

less severe- oral cephalexin (Keflex) 250mg QID/ 500mg BID x 5-10 days or dicloxacillin (Dynapen) 250mg QID x 5-10 days, Bactrim if suspected MRSA

severe- IV ceftriaxone (Rocephin), levofloxacin (Levaquin), nafcillin (Unipen)

Erysipelas

AKA St. Anthony’s Fire

edematous, spreading, well circumscribed, hot, erythematous area, w/ or w/o bullae

superficial form of cellulitis, on central face

caused by Group-A beta-hemolytic Strep

symptoms- pain, fever, chills, rash (after others)

rash starts as bright red spot, progresses to clearly demarcated, glistening, smooth, red plaque

Erysipelas treatment

urgent, can cause death from systemic toxicity

IV antibiotics for first 48 hrs- Penicillin G

oral antibiotics x 7 days- Pen VK 250mg QID, Dicloxacillin 250mg QID, Cephalexin 250mg QID

Folliculitis

inflammatory process of hair follicle from infection, chemical irritation, physical irritation

caused by Staph, trauma, scratching, shaving

Pseudo follicilitis

foreign body reaction when hair curves into skin after being cut against growth pattern

Folliculitis treatment

antibacterial soap, warm wet dressing

localized- Bactroban ointment TID x 5 days

extensive/spreading- oral antibiotics

Hot Tub Folliculitis

start 1-4 days after being in hot tub, may resolve spontaneously

caused by Pseudomonas

treatment- ciprofloxacin (Cipro) 500mg BID x 5 days

Abscess

localized collection of pus, intensely painful, red, tender, indurated

caused by Staph aureus if on trunk, extremities, head, neck, in axillae, or by organisms found in stool if on butt, inguinal/perineal area

will progress to a point/head, may drain spontaneously

Abscess

warm compress to cause head/point, then incision, drain, pack

oral antibiotics- cephalexin (Keflex) 500mg BID or 250mg QID

Furuncle abscess

abscess involving hair follicle and surrounding tissue, uncomfortable, maybe painful

caused by Staph aureus

found on neck, breasts, face, butt

Carbuncle abscess

collection of furuncles connected subcutaneously, uncommon

found on back of the neck, may have fever

MRSA (Methicillin Resistant Staph Aureus)

resistant to β-lactam antibiotics, macrolides, quinolones, clindamycin, sometimes Bactrim

can be hospital or community required, latter becoming increasingly common

risk factors- close skin-skin contact with cuts/abrasions, crowded living conditions, poor hygiene

MRSA treatment

Bactrim if possible or IV vancomycin or Zyvox

MRSA prevention

susceptible groups add 1/4c bleach to bathwater 1-2 x week

document people with colonized MRSA in nares (1%), treat with Bactroban ointment BID x 5 days

Warts

caused by HPV, 12 high-risk cancer strains

Common warts- 16, 18 (70%), Genital Warts 6, 11

6 types- common, periungual, flat, filiform, plantar, genital

Common warts

aka verruca vulgaris, most common on hands and knees

dome-shaped with irregular surfaces

spread by skin-skin contact, contact with contaminated surfaces, autoinoculation

common in kids