Dermatology - Common Skin Diseases

From Iusmicm

[edit] Common Skin Diseases

[edit] Acne

Acne is a disorder of the pilosebaceous glands
There are 4 aspects of acne; required, treated:
- Compaction of the gland
  - Compaction results in comedone plugs
  - Tx: topical comedolytics like retinoic acid and benzoyl peroxide
- Increased activity of the gland
  - Tx: systemic retinoids, antiandrogens (contraceptive pills, aldactone)
- Accumulation of stuff behind an obstruction
  - The "stuff" is usually sebaceous and keratinous debris
- Proliferation of a bacteria
  - Tx: antibiotics; topical (erythromycin, clindamycin), systemic (tetracycline, erythromycin)
- Usually the bacteria is P. acne
Tx goal of acne is to prevent scarring
- No one should suffer acne in this day!
- Milk products can exacerbate acne.

Recall the normal anatomy of skin: sebum from the sebaceous gland coats the growing follicle

[edit] Cutaneous characteristics of Acne

Distribution: face, chest, back (upper, lower), buttocks
Two morphologies: non-inflammatory and inflammatory
- There is also "cystic", "truncal acne", "acne excoriee"
Acne can result in significant scarring

Non-inflammatory: closed (whiteheads) and open (blackheads) comedones
- Blackheads are oxidized melanine, not a dirty face!

Inflammatory:
- Papules, pustules, nodules, cysts

Cystic:
- Generates large, erythmatous, raised non-ulcerated cysts

Truncal acne:

Acne excoriee:
- Occurs especially in females (young ladies)
- This is a psychological issue: pt is picking at the skin

[edit] Impetigo and Folliculitis

[edit] Cutaneous characteristics of Impetigo and Folliculitis

Impetigo can be classified with modifiers: "non-bullous", "bullous", "folliculitis", "furunculosis / boils"
- Think honey crusting

Non-bullous impetigo: erythematous patches with yellow crust (scabby); around the nose / mouth (eyes, ears, too); associated with beta-hemolytic streptococcus

Bullous impetigo: peripheral erythema with central bulla with cloudy content white / yellow exudate; replaced by a crusty patch (upon rupture); associtead with staphylococcus aureus
- Has a "skirt"
- Can be very red macule / patch when bullous has ruptured

Folliculitis: associated with unclean hot tubs / pools / showers / baths; associated with psuedomonas aeriugus; fomites (fomes = singular; anything that can carry the agent of disease)
- Folliculitis is usually bacterial in etiology
- Look for pustules

Furunculosis / Boils:
- Can be painful, tender
- May need to be lanced (may be as good as an antibiotic)

Carbuncle
- Many coalesced boils / furuncules
- Has multiple drainage sites

[edit] Dermatophyte Infections

Dermatophyte infections are ringworm infections
- Tinea = ringworm
Dermatophyte infections are called "tinea" and are modified by a descriptor of the location: capitis (scalp), croporis (body), cruris (groin), pedis (feet), manuum (hand), faciale (face), unguium (nails), versicolor (superficial yeast infection)
Dermatophytes can be dx via visualization under a prepped slide: vigorously rub area with gauze, collect small tissue sample that rubbed off, prep slide, look for tiny shiny dots (dermatophyte spores)

[edit] Tinea capitis

Kerions and alopecia areata are two a common tinea capitis reaction patterns when fungi is found in the dermis of the scalp.
- A reaction after dermatophytes move down the hair follicle; usually not inflammed; should not be lanced;
- Give antifungals orally

[edit] Tinea facei

Dermatophytes come from: relatives, animals, and school mates.

[edit] Tinea corporis

Demonstrates well demarcated, scaly edges.
Well demarcated edges can be used as a site of sample collection via scraping with a blade.

[edit] Tinea cruris

[edit] Tinea pedis

Tinea pedis is described as a "scaly moccasin"
- Can also form ulcers
- Two-feet-one-hand syndrome = Tinea

[edit] Tinea incognito

Steroids can cause tinea incognito

[edit] Tinea unguium

Tinea unguium causes onychomycosis (fungal infection of the nail)
- Must treat with oral agents, topicals won't work

[edit] Tinea versicolor

Tinea versicolor can be hypopigmented OR hyperpigmented
Tinea versicolor is associated with malassezia furfur--a yeast that looks like spaghetti and meatballs.
- Scrapings will reveal hyphae
- Use antifungal shampoos

[edit] Warts

Recall that warts are caused by human papilloma virus.
- Recall that HPV causes many different cancers
The common wart is called verruca vulgaris
The flat wart is called verruca plana
The plantar wart is called verruca plantaris plantar
The genital wart is called condylomata accuminata
Other types of warts include: filiform warts, cutaneous horns,
Mucosal warts are found in the mouth and the vagina.
- Vaginal warts are associated with cervical dysplasias that can result in cervical cancer.

[edit] Verruca vulgaris (common wart)

[edit] Verruca plantaris plantar (plantar wart)

Can also be described as "mosaic"
Show up here because we don't have enough langerhans cells in the plantar surface

[edit] Other types of warts

Filiform wart:
Cutaneous horn:
- Note that cutaneous horns can have a wart, a basal cell carcinoma, or a squamous cell carcinoma at its base

[edit] Verruca plana (plane wart)

Often in children, often on the face
Very subtle
Can be hypopigmentation
Higher incidence in AIDS pts

[edit] Condylomata accuminata (genital wart)

HPV 6,7, 16, 18 cause anogenital warts / conylomata accuminata!
- HPV 16, 18 can cause cervical cancer
HPV 5, 8, 21 = squamous cell carcinoma

[edit] Tx of warts

Cryotherapty with liquid nitrogen can be used to kill infected and surrounding cells.
No great treatment

[edit] Molluscum Contagiosum

Molluscum contagiosum is associated with immune suppressed pts.
Molluscum contagiosum is very contagious.
Associated with shared baths / pools as well as wrestlers.

[edit] Insect Bites

Insect bite reactions occur after stings and bites and each has a characteristic morphology.
Common agents include:
- stings: bees, hornets, wasps, yellow jackets, ants
- bites: mosquitos / fleas, bed bugs, ticks, spiders
All bites / stings can cause anaphylaxis; ask if they have swelling of tongue, trouble breathing, etc.

Morphologies:
- Bees (stings): generates urticaria (hives) or even an anaphalactic reaction; swelling
- Fire ants (sting): generates papules that become vesicular and then pustular
- Mosquitos / fleas / flies (sting): generate a papular urticaria affecting acral exposed parts of limbs; hives, excoriations, bullae
  - Urticaria: rash of round, red welts on the skin that itch intensely, sometimes with dangerous swelling
  - Acral: of or pertaining to peripheral body parts, such as toes and fingers
- Bed bugs (bite): urticarial (breakfast, lunch, dinner)
- Ticks (esp. ioxedes scapularis; bite): generate erythema migrans lymes disease (borrelia infection)
  - Note that the characteristic rash is pathognomonic.
- Spider (esp. brown recluse; bite): necrosis

Bee (sting): look for hives and swelling

Fire ant (sting): look for papules that move on to vesicles and pustules

Mosquitos / fleas / flies: look for papular urticaria (red, round welts with itching and swelling) on the acral areas
- Probably from bugs on a pet or in the play-area
- Not all siblings / family members will get it