Dermatologic System

Question 0

Squamous cell carcinoma

Answer 0

• Second most common skin cancer (20%)
• Arises from epidermal cells
• Most commonly found on head, neck, and hands
• RFs: sun exposure, pale skin, chronic inflammation, immunosuppression, xeroderma pigmentosum, arsenic
• Precursor is actinic keratosis
• Sx: raised, slightly pigmented, ulceration/exudate, chronic scab, itchy
• Dx: excisional bx if small, incisional bx if large
• Tx: Lesions less than 1cm=excise with .5cm margin. Lesions greater than 1cm= resect with 1-2cm margin.
• Palpable LN may indicate metastasis. These pts will eventually die.
• Prognosis is very good if totally excised and no LN involvement.

Question 1

Basal Cell Carcinoma

Answer 1

• Most common skin cancer (75%)
• Arises in the germinating basal cell layer of epithelial cells
• RFs: sun exposure, fair skin, radiation, chronic dermatitis, xeroderma pigmentosum
• Most commonly found on head, neck, and hands
• Sx: slow growing, scaly/scab, may have ulceration w/ or w/o pigmentation, “pearl like” appearance.
• Dx: excisional or incisional bx
• Very low risk of metastasis

Question 2

Melanoma

Answer 2

• Malignant transformation of the melanocyte (which is derived from neural crest cells)
• Pts at greatest risk are white, blonde/red hair, fair skin, freckles, hx of blistering sunburns, blue/green eyes, actinic keratosis
• Most commonly found on skin, eyes, and anus.
• Characteristics: pigmented lesion with irregular border, surface, and coloration.
• ABCDs: asymmetry, border irregularity, color variation, diameter >6mm
• 4 major types: superficial spreading, lentigo maligna, acral lentiginous, and nodular.
• Superficial spreading= most common type. Occurs in sun and non sun exposed areas.
• Lentigo maligna=malignant cells are superficial. Least aggressive type.
• Acral lentiginous= palms, soles, subungual, and mucous membranes.
• Nodular= vertical growth, most aggressive type.
• Common sites of mets: nodes, lung, liver, bone, heart, brain, small bowel mucosa.
• Dx: excisional bx or incisional bx if large
• The first LN in the draining chain is the sentinel LN and reflects the metastatic status of the group of LNs.
• In situ= .5cm margin
• less than or equal to 1cm= 1cm margin
• 1-4cm= 2cm margin
• > 4cm= 3cm margin

Workup: PE, LFTs, CXR, bone scan

Question 3

Condyloma Acuminata(genital warts)

Answer 3

• Sx: pruritic, heaped up lesion, pink/white
• Dx: PE, HPV DNA test, cytology
• Tx: Burn(podophillin, tri/bichloracetic acid), laser, cryotherapy

Question 4

Burns

Answer 4

• Alkali burns are more serious than acid burns.
• Electrical burns= most of the destruction is internal because the route of least electrical resistance follows nerves, blood vessels, and fascia.
• Rule of 9s: arm=9%, leg=18%, ant trunk=18%, post trunk=18%, head=9%, perineum=1%.
• Burn pts should get tetanus prophylaxis in the ER.
• Need to check pt’s urine output(goal is 30-50cc), check for eschar, and compartment syndrome.
• Signs of smoke inhalation: smoke/soot in sputum/mouth/nose, nasal/facial hair burns, carboxyhemoglobin(treat with 100% O2), throat/mouth erythema, hx of loss of consciousness/explosion/fire in small area, dyspnea, low O2sat, confusion, HA, coma. Smoke inhalation can be diagnosed with bronchoscopy.
• Burn shock: loss of fluid from the intravascular space->causes leaky capillaries->requires crystalloid infusion.
• Crystalloid fluids given through 2 large bore peripheral venous catheters.
• Do NOT give glucose containing IVF in the first 24hrs.
• After 24hrs, give colloid fluids (D5W and 5% albumin)
• Measure volume status through urine output, BP, HR, peripheral perfusion, and mental status.
• Burn wound infections= increased WBC with left shift, discoloration of eschar, green pigment, necrotic skin lesion, edema, ecchymosis, hypotension.

Minor burns: gentle cleansing with nonionic detergent, debridement of loose skin, topical antibacterial, cover with sterile dressings.
-Major burns: cleansing and application of topical antibacterial agent.

-Complications: pneumonia, central line infection.

• Need to monitor Na closely after a burn.
• Change central lines every 3-4 days.

Question 5

Cellulitis

Answer 5

• Blanching erythema from superficial dermal/epidermal infection.
• Strep>Staph
• Sx: red, hot, swollen, tender skin, fever/chills
• Dx: clinical, wound culture
• Tx: 7-10 days of antibiotic, may need IV abx.

Question 6

Pressure Ulcers

Answer 6

• Ischemic necrosis due to continuous pressure
• Grade I= persistent redness
• Grade II= partial thickness skin loss
• Grade III=full thickness skin loss
• Grade IV=tissue necrosis, bone and muscle damage.

-Tx:hydrocolloid dressings, may require surgical debridement.

Question 7

Wounds

Answer 7

• Primary wound closure= suture wound closes immediately
• Secondary wound closure= wound is left open, heals over time w/o sutures, heals by granulation, contraction, and epithelialization
• Delayed primary closure= suture wound closes 3-5 days after incision
• Sutured wound epithelializes in 24-48 hours
• After primary closure, dressing should be removed on post op day 2
• Wet to dry dressing= damp gauze placed on granulating wound, allowed to dry, then removed for microdebridement
• Infection, ischemia, DM, malnutrition, anemia, steroids, cancer, radiation, and smoking all inhibit wound healing.
• Vit A can reverse effects of steroids
• Abdominal wound dehiscence= opening of fascial closure-need to return to the OR

Question 8

Post op drug eruptions/urticaria

Answer 8

• Usually occur 7-14 days after exposure to a new drug. If before that, likely not due to the drug.
• Generally widespread, symmetrical, and pruritic. Will last 1-2 days after stopping the drug.
• Dx: clinical
• Tx: antihistamines, topical steroids

Question 9

Hidradenitis suppuratia

Answer 9

• Occurs in sebaceous glands and hair follicles.
• Found in armpits and groin.
• Sx: blackheads, red bumps, itchy/burning, painful, may drain pus.
• Dx: PE, culture of draining area
• Tx: Abx, NSAIDs, corticosteroids, immunosuppressants, TNFalpha inhibitors, oral retinoids. If severe= incision and drainage, surgical removal.

Question 10

Lipomas

Answer 10

• Slow growing, mobile, nontender.
• Dx: PE, bx to r/o liposarcoma, CT/MRI if deep/large
• Tx: steroid injections to shrink the size, surgical removal.

Question 11

Epithelial inclusion cysts

Answer 11

• Thin layers of epidermal cells filled with epithelial debris.
• Sx: soft to firm, filled with odorous/cheesy material, elevated, may have dimple at site of attachment.
• Most commonly found on face, scalp, ears, neck, back.
• Tx: surgical excision.

Question 12

First Degree Burn

Answer 12

• Epidermis only
• Sx: painful, dry red areas.
• Tx: keep clean, +/- neosporin, pain meds.

Question 13

Second degree burn

Answer 13

• Epidermis and varying levels of dermis
• Sx: Painful, hypersensitive, swollen, mottled areas with blisters.
• Tx: remove blisters, antibiotic ointment, dressing, pain meds.

Question 14

Third degree burn

Answer 14

• all layers of the skin including the entire dermis
• Sx: painless, insenate, swollen, dry, mottled white, charred areas.
• Tx: early excision of eschar(w/i one week), split thickness skin graft.
• Has highest amount of water evaporation.

Question 15

Fourth degree burn

Answer 15

-into the bone or muscle