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CH7 Integumentary System

Acral Lentiginous Melanoma

  • Subtype of melanoma most common in darker-pigmented individuals.
  • Lesions: dark brown to black; locations include nails (subungual), palms, soles; mucous membranes rarely involved.
  • Subungual melanomas appear as longitudinal brown-to-black bands on the nail bed. See Figure 7.1 in lesson.

Actinic Keratosis

  • Precancerous precursor to squamous cell carcinoma.
  • Typical patient: older-to-elderly fair-skinned adults with numerous dry, round, red lesions with rough texture that do not heal; slow growing.
  • Common locations: sun-exposed areas (cheeks, nose, face, neck, arms, back).
  • Risk: higher with light-colored skin, hair, or eyes.
  • In some cases, precancerous lesion for squamous cell carcinoma is possible.
  • Early childhood history of severe sunburn increases risk for skin cancers (SCC, BCC, melanoma).

Anaphylaxis (Angioedema, Hives)

  • Severe, life-threatening hypersensitivity reaction related to IgE- and IgG-mediated mechanisms and immune complex/complement-mediated mechanisms.
  • Common outpatient triggers: foods (most common), insect stings, certain drugs.
  • Presentation: acute onset (minutes–hours) with flushing, hives, angioedema, dyspnea, wheezing, tachycardia or bradycardia, hypotension, hypoxia, or cardiac arrest.
  • Treatment: epinephrine 1 mg/mL, 0.3–0.5 mg IM in mid-outer thigh; can repeat every 5–15 min if poor response.
  • In anaphylaxis, there are no absolute contraindications to epinephrine. Call 911.

Basal Cell Carcinoma

  • Common skin cancer arising from basal layer of epidermis.
  • Clinical forms: nodular, superficial, morphed (morpheaform).
  • Nodular BCC: pink/flesh-colored papule with pearly/translucent quality and telangiectatic vessels, often on the face.
  • Superficial BCC: trunk lesions; slightly scaly, non-firm macules/patches/plaques red to pink; may have atrophic or ulcerated center that does not heal.
  • Morpheaform: smooth, flesh-colored or light pink papules/plaques; atrophic, firm/indurated with ill-defined borders.
  • Most important risk factor: ultraviolet radiation exposure in sunlight.

Brown Recluse Spider Bites

  • Brown recluse spiders (Loxosceles reclusa) mostly found in the midwestern and southeastern U.S.
  • Systemic symptoms: fever, chills, nausea, vomiting; deaths rare but have occurred in children <7.
  • Any child with systemic signs should be hospitalized due to potential hemolysis.
  • Most spider bites occur on arms, upper legs, or trunk; bite may be pinprick or painless.
  • Early signs: swelling, redness, tenderness; blisters within 24–48 hours; central necrotic eschar forms; sloughing can leave an ulcer that heals over weeks.

Melanoma

  • Dark-colored moles with uneven texture, variegated colors, irregular borders; diameter ≥ 6 ext{ mm}; may be pruritic.
  • If in the nail beds (subungual melanoma), may be very aggressive.
  • Locations: can be anywhere, including retina.
  • Risk factors: family history (≈ 10 ext{%} of cases), extensive/intense sun exposure, blistering sunburn in childhood, tanning beds, high nevus count/atypical nevus, light skin/eyes.

Meningococcemia (Meningitis)

  • Acute systemic meningococcal disease; meningitis with or without meningococcemia; or meningococcemia without meningitis.
  • Meningitis: inflammatory disease of leptomeninges.
  • Meningococcemia: systemic bloodstream infection by Neisseria meningitidis (gram-negative).
  • Symptoms: sudden sore throat, fever, headache, stiff neck, photophobia; LOC changes (drowsiness to coma).
  • Rash: abrupt onset of petechial (small red spots) to hemorrhagic rashes (pink to purple) in axillae, flanks, wrists, ankles.
  • Hypotension and shock common. Up to 25% with cutaneous hemorrhage and DIC.
  • Procalcitonin usually elevated in bacterial meningitis.
  • Fulminant cases can lead to death within hours.
  • Risk groups: people in close quarters (dorms, nurseries, military barracks), asplenia, functional or anatomic splenic defects, HIV, complement deficiencies; infants 3–12 months.
  • Prevention: CDC vaccination recommendations for higher-risk groups and adolescents.
  • Prophylaxis for exposure: rifampin; initial therapy: ceftriaxone. Follow aerosol droplet precautions.

Rocky Mountain Spotted Fever (RMSF)

  • Etiology: Rickettsia rickettsii transmitted by ticks; most common spotted fever in the U.S.
  • Presentation: abrupt high fever, chills, severe headache, nausea/vomiting, photophobia, myalgia, arthralgia; rash appears 2–5 days after fever onset.
  • Rash: small red petechiae starting on wrists, forearms, ankles (sometimes palms/soles) then spreading to trunk; ~10% may be without rash.
  • Seasonality: spring to early summer; outdoor activity risk.
  • Treatment: first-line doxycycline for children and adults; tick repellents DEET on skin and permethrin on clothing/gear recommended.

Shingles Infection of the Trigeminal Nerve (Herpes Zoster Ophthalmicus)

  • Reactivation of varicella-zoster virus involving the ophthalmic branch (CN V).
  • Presentation: sudden eruption of multiple vesicular lesions on one side of scalp/forehead, periorbital area, nose; lid swelling and redness; photophobia, eye pain, blurred vision.
  • If rash on tip of nose (Hutchinson sign) suspect ocular involvement; refer to ophthalmology or ED urgently.

Stevens–Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN)

  • Severe mucocutaneous reactions; lesions start as target/bull’s-eye; widespread erythema multiforme-like lesions with mucosal involvement (eyes, nose, mouth, esophagus, bronchial tree).
  • Prodrome: fever with flu-like symptoms 1–3 days before rash.
  • SJS:
  • Triggers: medications (allopurinol, anticonvulsants like lamotrigine, carbamazepine, phenobarbital; sulfonamides; oxicam NSAIDs).
  • Mortality: ~10 ext{%} in SJS; up to 50 ext{%} in TEN.
  • Risk factors: HIV infection, genetic factors, SLE, malignancies.

Subungual Hematoma

  • Direct trauma to the nail bed causing bleeding trapped under nail.
  • If hematoma > 25 ext{%} of nail area, risk of permanent ischemic damage to nail matrix if not drained.
  • Can be simple or associated with fingertip avulsion, mallet finger.
  • Drainage (trephination) method: heat a straightened end of a steel paperclip or 18-gauge needle heated by flame; create 3–4 mm hole to drain. Blood may drain for 24–36 hours. Additional steps: neurovascular exam, tendon assessment; radiographs if large hematomas; consider antibiotics and tetanus status; consider hand surgery consult.

Comparison of Common Skin Rashes

  • Impetigo: honey-colored crusts, fragile bullae, pruritic.
  • Measles: Koplik’s spots (small white spots on red base in buccal mucosa).
  • Scabies: extremely pruritic, worse at night; serpiginous rash in interdigital webs, waist, axilla, genitalia.
  • Scarlatiniform (Scarlet) fever: sandpaper rash with sore throat.
  • Tinea versicolor: hypopigmented round-to-oval macules on shoulders/back; not pruritic.
  • Pityriasis rosea: herald patch first; “collarette” of scale; Christmas tree pattern rash along cleavage lines.
  • Molluscum contagiosum: smooth 2–5 mm dome-shaped papules with central umbilication and white plug.
  • Erythema migrans: red target-like lesions with central clearing (early Lyme).
  • Meningococcemia: purplish/red painful lesions all over body; high fever; rifampin prophylaxis for close contacts.
  • RMSF: red spot-like rashes that begin on hands/palms and feet/soles; fever and headache.
  • Brown recluse bite: swelling, tenderness; blisters within 24 hours; potentially necrotic eschar.

Normal Findings — Anatomy of the Skin

  • Three layers: epidermis, dermis, subcutaneous.
  • Epidermis: no blood vessels; nourished by dermis; two layers: outer keratinized dead cells; bottom layer houses melanocytes and vitamin D synthesis.
  • Dermis: blood vessels, sebaceous glands, hair follicles.
  • Subcutaneous: fat, sweat glands, hair follicles.
  • Glands: Apocrine (axilla, groin); Eccrine (major sweat glands; heat dissipation/thermoregulation).
  • Skin exam for darker skin: urticaria/palpation for induration, persistent ashy gray in very dry skin; keloids, hyperpigmentation, traction alopecia common in African descent; jaundice harder to assess; pseudofolliculitis barbae (razor bumps) common in shaved beards; vitamin D synthesis requires longer sun exposure in darker skin; vitamin D deficiency during pregnancy risks infantile rickets.

Dermatologic Terms

  • Acral: distal limbs (hands/feet) (acral melanoma).
  • Annular: ring-shaped.
  • Exanthem: cutaneous rash.
  • Extensor: skin outside of joints.
  • Flexor: skin folds over joints.
  • Flexural: skin folds.
  • Intertriginous: areas where skin touches (axillae, groin, skin folds).
  • Maculopapular: pink/red rash with small raised bumps (viral).
  • Morbilliform: measles-like rash.
  • Nummular: coin-shaped.
  • Purpura: bleeding into skin (petechiae small; ecchymoses larger).
  • Serpiginous: snake-like.
  • Verrucous: wart-like.
  • Xerosis: dry skin.

Melanoma Screening (A, B, C, D, E)

  • A: Asymmetry
  • B: Border irregular
  • C: Color variation in the lesion
  • D: Diameter > 6 ext{ mm}
  • E: Enlargement or change in size
  • Other signs: intermittent bleeding with minor trauma; new itching.
  • Tips:
    • Melanoma can be a brown-to-dark papule, not always flat; irregular borders and other signs can indicate melanoma.
    • Distinguish actinic keratosis (precursor to SCC) from seborrheic keratoses (benign).
    • Actinic keratosis arises from chronic UV exposure.

Skin Cancer Statistics

  • Skin cancer is the most common cancer in the United States.
  • Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) are the most common types.
  • Melanoma is the third most common but the most fatal due to metastasis tendency.

Primary and Secondary Skin Lesions

  • Primary lesions:
    • Macule (< 1 ext{ cm}, flat, nonpalpable): freckles, lentigo.
    • Papule (≤ 1 ext{ cm}, palpable solid): nevi, acne, cherry angiomas.
    • Plaque (> 1 ext{ cm}, flattened elevated): psoriatic plaques.
    • Vesicle (< 1 ext{ cm}, fluid-filled): herpes lesions.
    • Bulla (> 1 ext{ cm}, blister): impetigo, second-degree burns, SJS lesions.
    • Pustule: contains purulent fluid (acne pustules).
  • Secondary lesions: result from evolution/changes of primary lesions (lichenification, scale, crust, ulceration, scar, keloid).

Urticaria (Hives)

  • Erythematous, raised lesions with discrete borders; irregular, oval, or round.
  • Lesions appear and disappear within hours; can be recurrent (daily) and last 24 hours.
  • Triggered by medications, infections, insect bites, latex allergy, etc.
  • If angioedema or progression to anaphylaxis, it can be life-threatening.

Seborrheic Keratoses

  • Soft, wart-like, fleshy growths on trunk, especially the back; appear ‘pasted on’ skin.
  • Color ranges from light tan to black; generally painless; occur with age.

Xanthelasma

  • Raised, soft, yellow plaques under the eyebrows or upper/lower eyelids; symmetric.
  • If <40 years, rule out hyperlipidemia; ~50% with xanthelasma have hyperlipidemia.
  • If xanthomas on fingers, pathognomonic for familial hypercholesterolemia.
  • Order fasting lipid profile (8–12 hours).

Melasma (Mask of Pregnancy)

  • Bilateral brown-tan macules/patches on sun-exposed skin (cheeks, malar area, forehead, chin).
  • Common in reproductive-age women; risk factors include genetics, sunlight, skin phototype, hormonal factors (pregnancy, OCP).
  • Stains can be permanent but may lighten over time.

Vitiligo

  • Loss of epidermal melanocytes; white patches with irregular shapes; chronic and progressive.
  • Can affect anywhere; lesions may be stable or flare with autoimmune diseases (e.g., Graves’, Hashimoto’s, RA, psoriasis, pernicious anemia).
  • More obvious in darker skin; refer to dermatologist; sunscreen recommended; affects self-image.

Cherry Angioma

  • Benign bright cherry-red papules (1–4 mm); due to nests of malformed arterioles.
  • Blanch with pressure; common in middle-aged to older adults; no treatment needed.

Lipoma

  • Soft, fatty, painless subcutaneous tumors; usually 1–10 cm or larger; smooth with discrete edge.
  • Most common benign soft tissue tumor.
  • Treatment: surgical excision if needed.

Nevi (Moles)

  • Round macules to papules (junctional nevi) with colors from light tan to dark brown.
  • Borders may be distinct or irregular.
  • Junctional nevi are macular/minimally raised; compound nevi are pigmented papules; colors tan to medium brown.

Xerosis

  • Inherited disorder with extremely dry skin; may involve mucosa.

Acanthosis Nigricans

  • Diffuse velvety thickening of skin, usually behind the neck and in the axilla.
  • Associated with diabetes, metabolic syndrome, obesity, GI tract cancers.

Acrochordon (Skin Tags)

  • Painless, pedunculated outgrowths; common on neck and axillary area; more in diabetics and obese.
  • May twist/traumatize and necrose; can drop off.

Topical Steroids

  • Indispensable in inflammatory/autoimmune skin diseases (atopic dermatitis, contact dermatitis, psoriasis, vitiligo, lichen planus, discoid lupus).
  • Do not combine antifungal with topical steroids if fungal etiology suspected.
  • Potency ranges from Class I (super potent) to Class VII (least potent); see Table 7.2.
  • Best applied within 3 minutes after bathing.
  • Sensitive skin areas (face, genitals, intertriginous areas) absorb more steroid; avoid fluorinated steroids in children <12 unless necessary; use least potent OTC hydrocortisone 1–2% first.
  • HPA axis suppression possible with prolonged or excessive use; potential for striae, atrophy, telangiectasia, acne, hypopigmentation.

General and Potency Guidelines for Topical Steroids

  • Super-high potency: for severe dermatoses on non-facial/non-intertriginous areas; up to 2 weeks; effective on palms/scalp/soles.
  • Medium-high: mild-to-moderate non-facial/non-intertriginous areas.
  • Low-medium: larger areas needing treatment.
  • Low-potency: eyelids/genital areas for limited duration; ophthalmic forms used for eyelids.
  • Examples by class (from the text):
    • Class I: Halobetasol propionate (Ultravate) 0.5% BID (weeks max)
    • Class II: Halcinonide (Halog) 0.1% BID to TID
    • Class III: Triamcinolone acetonide (Kenalog) 0.5% BID to TID
    • Class IV: Mometasone furoate (Elocon) 0.1% BID to QID
    • Class V: Desonide (Desonate) 0.05% BID to QID
    • Class VI: Fluocinolone (Synalar) 0.01% BID to QID
    • Class VII: Hydrocortisone 1% OTC BID to QID

Acne Vulgaris (Common Acne)

  • Inflammation/infection of pilosebaceous units with multifactorial causes: androgens, Cutibacterium acnes, follicular hyperproliferation, genetics.
  • Locations: face, shoulders, chest, back; peak incidence during puberty/adolescence.

Acne Severity and Treatments

  • Mild Acne (topicals only)
    • Features: scattered open comedones (blackheads) and closed comedones (whiteheads); may have small papules.
    • First-line: topical retinoids, benzoyl peroxide, topical antibiotics.
    • Examples: Tretinoin topical (Retin-A) 0.25% cream every other night x 2–3 weeks, then nightly; alternative azelaic/salicylic acid OTC.
    • Retinoids help reduce facial wrinkles and pigment; skin irritation common in initial weeks; photosensitivity; use sunscreen.
    • If no improvement in 8–12 weeks, switch to topical dapsone, minocycline, or clascoterone.
  • Moderate Acne (topicals + antibiotics)
    • Features: inflammatory papules and pustules with comedones.
    • Treatments: systemic therapy (oral isotretinoin, oral antibiotics, hormonal therapies like OCPs or spironolactone).
    • Combine systemic with topical therapies (except isotretinoin alone).
    • For severe nodular acne: isotretinoin is recommended as initial therapy; may combine with systemic glucocorticoids.
  • Isotretinoin details (teratogenic): REMS program (iPLEDGE) required in the U.S.
    • Two forms of contraception; monthly pregnancy testing; discontinue on certain adverse effects (depression, visual/hearing changes, GI symptoms, pancreatitis, hepatitis).
    • If no improvement: add oral antibiotics (tetracyclines like minocycline, doxycycline) for ~3–4 months; tetracyclines are category D due to tooth discoloration if used during pregnancy or before age 8.
    • Other: certain oral contraceptives may be indicated; dairy products may affect acne.

Actinic Keratoses (AK) Revisited

  • Precancerous lesions that can progress to squamous cell carcinoma; ~60% of cutaneous SCCs arise from pre-existing AKs.
  • Most common in older adults with chronic UV exposure.
  • Classic case: older adult with numerous dry, pink-to-red, rough lesions on sun-exposed areas.
  • Treatment options: dermatologist biopsy (gold standard); surgical removal; cryotherapy; topical fluorouracil 5% (5-FU) or imiquimod; 5-FU causes inflammation (erythema, oozing, crusting) that resolves in weeks.

Bioterrorism and Vaccines (Public Health Context)

  • Anthrax: caused by Bacillus anthracis; cutaneous (most common), GI, pulmonary; exposure history important; treatment includes doxycycline or ciprofloxacin; post-exposure prophylaxis 42–60 days.
  • Smallpox (Variola Virus): historically eradicated in 1977; antiviral tecovirimat (Tpoxx) approved; vaccines (Vaccinia immune globulin for special populations); vaccine guidelines emphasize exposure timing and contraindications.
  • FDA warning: avoid oral ketoconazole due to hepatic/hemodynamic risks; topical ketoconazole shampoo is safe.

Eye and Ocular-Region Considerations

  • Use ophthalmic-grade sterile creams/ointments for rashes near the eyes.

Wounds, Burns, and Injury Management

  • Wounds have four healing phases: hemostasis, inflammation, proliferation, remodeling.
  • Wound types:
    • Primary closure: clean, sharp wounds suitable for suturing within 12–18 hours; minimal scarring.
    • Secondary intention: wound left open to heal via granulation; more scarring.
    • Tertiary (delayed primary closure): contaminated wounds left open briefly, then closed later; most scar tissue.
  • High-risk wounds warrant referral (infected, contaminated, heavy bleeding, burns, facial/cosmetic concerns, joint involvement, foreign bodies).
  • Tetanus prophylaxis recommended if last dose >5 years ago; Tdap preferred if never had.
  • Common procedures require informed consent and discussion of benefits/risks.

Local Anesthesia and Infiltration Techniques

  • Local anesthetics commonly used: lidocaine (1%), with or without epinephrine; other options include bupivacaine, mepivacaine, procaine.
  • Lidocaine 1% onset 2–5 minutes; duration 30 minutes to 2 hours; watch for allergies, overdose and intravascular injection risks.
  • Direct infiltration technique: clean site, inject into subcutaneous tissue around wound margins; slow, small injections; test numbness after several minutes.
  • Digital nerve block (finger web space block): detailed technique provided (needles, volumes, steps); takes 5–10 minutes to take effect.

Suturing — General Rules and Techniques

  • Do not suture puncture wounds or human/animal bites; avoid heavily contaminated wounds.
  • Do not suture wounds older than 12 hours (12 hours for general wounds; 24 hours on face for some injuries).
  • Skin sutures: nonabsorbable synthetic sutures (e.g., nylon, Prolene) are common; curved cutting needles preferred for skin.
  • Suture size: smaller numbers with more zeros; 3–0 to 5–0 for skin lacerations; 11–0 for tiny vessels.
  • Technique: evert wound edges at 90-degree angle; use simple interrupted sutures; leave a tail for removal; avoid deep puncture wounds, animal bites, or contaminated wounds.
  • Suture removal timelines by location: face/neck ~5 days; scalp ~7–10 days; trunk/upper extremities ~7 days; lower extremities ~8–10 days; digits/palm/sole ~10–14 days.
  • Important: remove sutures to minimize scar; if infection or poor healing, avoid closure.

Skin Biopsy and Cryotherapy

  • Punch biopsy: assess bleeding risk; INR should be < 2.5 for biopsy; refer to dermatologist for facial biopsy or suspected melanoma.
  • Cryotherapy (cryoablation): various methods (open spray, dipstick, contact, tweezer); blistering first 12–24 hours, crusting, healing within days.
  • Contraindications: cold sensitivity issues (Raynaud, cryoglobulinemia), open wounds, compromised circulation, injury near eyes, lips, nails, cartilage, etc.
  • Adverse effects: hypopigmentation in darker skin; potential for scarring, alopecia, tissue distortion.

Lyme Disease (Early Lyme Disease)

  • Erythema migrans: expanding red rash with central clearing; typically appears 7–14 days after tick bite; flu-like symptoms may accompany; rash resolves in a few weeks.
  • Tick management: DEET on skin; permethrin on clothing.
  • Labs: two-step testing recommended—First step EIA; if positive or equivocal, second step IFA/Western blot. Antibody tests can be false-negative in the first 4–6 weeks.
  • Treatment for early Lyme disease: doxycycline 2x daily for 10 days; alternatives: amoxicillin 500 mg three times daily or cefuroxime axetil 500 mg twice daily for 14 days.
  • Tick removal: grasp the part closest to the skin (head) and pull upward with steady pressure; avoid using nail polish or heat.
  • If tick is engorged, consider a one-time doxycycline 200 mg dose.

Erysipelas

  • Subtype of cellulitis; involves upper dermis and superficial lymphatics; often caused by group A Streptococcus.
  • Facial erysipelas: assume MRSA; choose MRSA-active antibiotic.
  • Presentation: sudden onset of a hot, indurated, sharply demarcated red lesion; commonly on the lower legs; fever, chills, malaise, headache; regional lymphadenopathy possible.
  • Management: often require hospitalization due to bacteremia risk.

Folliculitis, Furuncles, and Paronychia

  • Folliculitis: infection of hair follicles with purulent material; usually self-limiting; avoid shaving or scrubbing; consider mupirocin.
  • Furuncles (boils): deeper infection of hair follicle; purulent drainage when fluctuant; warm compresses; if >2 cm or joint involvement, drainage and antibiotics.
  • Paronychia: infection around nail folds; often S. aureus/S. pyogenes/Pseudomonas; treat with soaking, topical antibiotics; incision and drainage for abscess; tetanus status.

Herpetic Whitlow

  • Viral skin infection of the fingers caused by HSV-1/HSV-2; acute painful red bumps and small blisters on the sides of fingers; may recur.
  • Treatment: analgesics/NSAIDs for pain; acyclovir if severe or immunocompetent patients; avoid sharing personal items; cover lesions.

Hidradenitis Suppurativa

  • Chronic inflammatory disease of apocrine glands; painful nodules, abscesses, pustules in axilla, mammary area, perianal, groin; more common in women.
  • Risk factors: genetics, smoking, obesity.
  • No cure; staged disease (Stage I to III).
  • Treatment plan:
    • Stage I: topical clindamycin; if fail, oral tetracycline (e.g., doxycycline or minocycline).
    • Stage II–III: oral tetracycline; rifampin in combination for extensive disease; consider retinoids, dapsone, adalimumab/infliximab for refractory disease; may require surgical excision for sinus tracts.
  • Emphasize lifestyle: warm compresses, wound care, smoking cessation, weight loss.

Impetigo

  • Acute contagious superficial bacterial infection, often caused by beta-hemolytic Streptococcus or Staphylococcus aureus; most common in young children (2–5 years).
  • Variants: bullous, nonbullous, ecthyma.
  • Presentation: acute onset of itchy pink-to-red lesions; vesiculopustules rupture; honey-colored crusts form after rupture.
  • Management: culture of crusts/wounds; limited lesions: topical mupirocin or retapamulin; numerous lesions: cephalexin or dicloxacillin; penicillin allergy options include erythromycin or clindamycin; daily hygiene and school reentry after 48–72 hours of treatment.

Meningococcemia — Prophylaxis and Care

  • Bacteremia due to Neisseria meningitidis; spread by respiratory droplets; meningitis is a medical emergency; mortality 10–15% if untreated.
  • Prophylaxis for close contacts: rifampin, ciprofloxacin, or ceftriaxone; close contacts defined by proximity and exposure history.
  • Vaccination guidance: MenACWY; MenB vaccine for certain high-risk groups. Lumbar puncture for CSF culture; blood/throat cultures; imaging as needed.

Molluscum Contagiosum

  • Dome-shaped papules (2–5 mm) with central umbilication; poxvirus infection; common in children; may be STI if lesions are genitally located.
  • Most immunocompetent individuals clear in 6–12 months.

Necrotizing Fasciitis (Flesh-eating bacteria)

  • Rapidly spreading infection; reddish to purplish lesions; bullae formation possible; high pain; requires ED referral.

Paronychia

  • Acute infection around the nail fold; commonly due to S. aureus or Streptococcus species or Pseudomonas; chronic cases associated with onychomycosis.
  • Management: warm baths; topical antibiotics; incision and drainage if abscess; avoid suturing in high-risk infections.

Pityriasis Rosea

  • Self-limiting (6–8 weeks); possible viral etiology; herald patch followed by Christmas-tree pattern rash.
  • Management: usually none; mild itching treated with mid-potency steroids; STI risk assessment if suspicion of secondary syphilis.

Psoriasis

  • Inherited disorder of rapid keratinocyte turnover; several phenotypes: plaque, guttate, erythrodermic, pustular.
  • Koebner phenomenon: plaques after trauma; Auspitz sign: pinpoint bleeding when scales are removed.
  • Classic case: pruritic erythematous plaques with silvery scales on scalp, elbows, knees; possible psoriatic arthritis.
  • Treatment tiers:
    • Limited disease: topical steroids and emollients; alternatives include topical retinoids, tar, vitamin D; localized phototherapy.
    • Severe disease: phototherapy; systemic agents (methotrexate, cyclosporine) and biologics (TNF inhibitors like etanercept, adalimumab).
  • Boxed warnings: topical tacrolimus has malignancy risk; biologics increase infection, malignancy, TB risk.
  • Complications: guttate psoriasis often follows Streptococcus; pustular psoriasis can be life-threatening with organ involvement.
  • Tips: methotrexate as a DMARD example.

Rocky Mountain Spotted Fever (RMSF) — Revisited

  • Emphasize early empiric treatment with doxycycline in suspected RMSF for all ages; delay increases mortality.
  • First-line dose: doxycycline 100 mg PO or 200 mg IV every 12 hours for 72 hours; pediatric dosing weight-based for <8 years.
  • RMSF is a reportable disease; diagnosis via antibody titers (IFA); early diagnosis depends on clinical suspicion.
  • Pearls: red spot rash starting on hands/feet with fever suggests RMSF; do not delay treatment for labs.

Rosacea

  • Chronic inflammatory skin disorder, more common in fair-skinned individuals; four subtypes: erythematotelangiectatic, papulopustular, phymatous, ocular.
  • First-line: symptom control and trigger avoidance (spicy foods, alcohol, sun).
  • Sensitive skin predisposition; avoid irritants; moisturizer recommended.
  • Mild–moderate treatments: topical metronidazole, azelaic acid, or ivermectin.
  • Moderate–severe: oral tetracycline or minocycline for 4–12 weeks; alternative antibiotics include clarithromycin with doxycycline.
  • Complications: rhinophyma; ocular rosacea (blepharitis, conjunctival injection).

Scabies

  • Infestation by Sarcoptes scabiei; transmission via close contact; incubation 4–8 weeks (may be asymptomatic initially).
  • Classic scabies: pruritic, worse at night; lesions in interdigital webs, axillae, waist, scrotum, penis; burrows visible (serpiginous lines).
  • Crusted (Norwegian) scabies: severe form with heavy mite burden; scalp and nails involved; highly contagious.
  • Treatment: permethrin 5% cream from neck down; wash off after 8–14 hours; repeat in 7 days; treat all household members; wash clothes/bedding; consider ivermectin for crusted scabies.
  • Pruritus relief may persist 2–4 weeks after cure; treat with H1 blockers or topical steroids.

Superficial Candidiasis and Intertrigo

  • Candida infections occur in warm, humid, occluded areas (intertrigo); satellite lesions common; obesity/diabetes increase risk.
  • Oropharyngeal candidiasis (thrush): white plaques with red base in oropharynx; treatment includes topical antifungals (clotrimazole, miconazole); systemic fluconazole for moderate-to-severe disease.
  • Skin candidiasis: treat with topical antifungals; keep area dry and well-ventilated.

Tinea Infections (Dermatophyte Infections)

  • Dermatophytes: Trichophyton, Microsporum, Epidermophyton; affect skin, hair, nails; ringworm examples.
  • Labs: fungal cultures; KOH smear shows pseudohyphae and spores.
  • Treatment philosophy:
    • Limited infections: topical antifungals (azoles, allylamines, ciclopirox, butenafine, tolnaftate).
    • Extensive/refractory or tinea capitis/onychomycosis: systemic antifungals (terbinafine, fluconazole, griseofulvin).
    • Nystatin not effective for dermatophytes; avoid topical steroids in fungal infections.
  • Common types include Tinea capitis, corporis, cruris, pedis, manuum, barbae, and unguium.
  • Black dot tinea capitis is common in U.S. African American children; systemic therapy is required; baseline LFTs recommended; avoid hepatotoxins; prevent spread via avoiding sharing combs, hats, towels, etc.

Lyme Disease (Early Lyme) — Labs and Management

  • Erythema migrans is pathognomonic; two-tier testing recommended: EIA first; if positive or equivocal, Western blot/IFA; serology can be negative early.
  • Early treatment: doxycycline 100 mg twice daily for 10 days (adults and children); alternatives: amoxicillin 500 mg three times daily or cefuroxime axetil 500 mg twice daily for 14 days.
  • Tick removal: remove head first; do not use nail polish, petroleum jelly, or heat.
  • If tick engorged, one-time doxycycline 200 mg is considered.
  • Complications: neuropathy (facial palsy), Lyme arthritis, chronic fatigue; test interpretation depends on stage.

Erysipeas and Related Rashes

  • Erysipelas vs cellulitis distinction: erysipelas involves upper dermis and lymphatics; facial cases treated with MRSA coverage if needed.

Varicella Zoster Virus Infections

  • Varicella (chickenpox) and shingles (Herpes zoster) are caused by VZV.
  • Chickenpox: contagious from 1–2 days before rash until all lesions crust; illness lasts ~2 weeks.
  • Shingles: contagious from onset of rash until crusted; risk of PHN higher in elderly/immunocompromised; treat within 48–72 hours for age >50 or immunocompromised.
  • Vaccines: Varicella vaccine (two doses for children/adolescents/adults); Shingrix (recombinant zoster vaccine) for adults 50+; contraindications include allergy to vaccine components, acute illness; pregnancy considerations.
  • Treatments: varicella antiviral therapy (valacyclovir) for immunocompetent and pregnant patients; uncomplicated zoster treated with acyclovir or valacyclovir; analgesia for PHN; lidocaine patches for PHN.

Vaccines and Warnings

  • Varicella vaccine dose schedule; contraindications include bone marrow malignancy, immunodeficiency, high-dose immunosuppression, pregnancy.
  • Shingrix: two-dose schedule; priority for adults 50+ regardless of prior varicella history; contraindications include allergy and acute illness; avoid during pregnancy.
  • Boxed warnings: attention to safety with tacrolimus and TNF inhibitors; infection/malignancy risk with biologics; TB risk monitoring prior to TNF inhibitors.
  • Pearls: varicella contagious until crusted; some vaccinated people may still develop lesions without crusting; shingles only occurs in those with prior chickenpox infection.

Wounds — General Concepts

  • A wound is a disruption to skin integrity; healing phases: hemostasis, inflammation, proliferation, remodeling.
  • Factors impairing healing: age, nutrition, immune status, mobility, stress, diabetes, medications (anticoagulants, steroids), pressure, smoking, infection.
  • Wound closure options: primary closure, secondary intention, tertiary (delayed primary) closure. Each has different scarring outcomes.
  • Criteria for burn center referral and TBSA estimation using Lund-Browder chart for children; Rule of Nines for adults; example calculation included in the text.
  • Minor burn management: superficial and partial thickness burns treated with cleansing, topical antimicrobials (e.g., bacitracin, polysporin), nonadherent dressings; avoid hydrogen peroxide; zinc oxide after healing to protect from sun exposure; avoid sun exposure on recently healed burns.
  • Major burns: full-thickness or deep burns; airway assessment; burn center referral; depth-based treatment strategies; avoid closure of infected wounds.

Classic Case Scenarios and Management Tips

  • Burn percent calculation practice example provided: 2 areas with 9% each and 18% anterior trunk equals 36% TBSA; specific management steps outlined.
  • Clenched-fist injuries require hand surgeon evaluation; C&S for wounds; distal pulse, ROM, tendon/nerve function assessment; x-ray for foreign body and fracture.
  • Retained foreign bodies: radiographs first-line; ultrasound or additional imaging if radiolucent objects suspected; some objects invisible on X-ray.
  • Minor burn management steps (practical): Silvadene (silver sulfadiazine) cream; nonadherent dressings; topical antibiotics; wound care and sun protection after healing.

Lyme, RMSF, and Tick-Borne Diseases — Quick Reference Summary

  • RMSF: doxycycline first-line across ages; treat early; tick exposure history important; DEET/permethrin use recommended.
  • Lyme: early erythema migrans treated with doxycycline; two-step serology; tick removal technique; prophylaxis if engorged tick removed within days; prevention strategies.

Practical Clinical Pearls and Exam-Oriented Tips

  • Melanoma screening emphasis on A, B, C, D, E plus bleeding and itch changes as warning signs.
  • Isotretinoin requires REMS program (iPLEDGE) due to teratogenicity; contraception and pregnancy testing mandatory.
  • MRSA risk factors in cellulitis and erysipelas; when purulent drainage is present, MRSA coverage may be needed.
  • Dermatologic treatments require balancing efficacy with potential adverse effects (e.g., steroids in children, immunosuppressants, and biologics).
  • Always assess vaccination status, exposure history (bioterrorism agents, RMSF-endemic regions), and occupational/environmental risks (ticks, animal exposures).

Quick Reference: Key Formulas and Numbers

  • Melanoma diameter threshold for screening concern: D > 6 ext{ mm}
  • Burn depth terms: superficial, partial-thickness (superficial/deep), full-thickness; fourth-degree denotes muscle/bone involvement.
  • TBSA estimation (adult Rule of Nines):
    • Arms/head: 9 ext{ extperthousand} per limb/region; each arm/head accounts for 9 ext{ extperthousand} of body
    • Legs/trunk: 18 ext{ extpercent} per leg; 18 ext{ extpercent} for anterior trunk; 18 ext{ extpercent} for posterior trunk
  • Two-step Lyme testing workflow: EIA first; if positive/equivocal, IFA/Western blot second step.

Summary Notes

  • This transcript covers a broad spectrum of dermatology-related topics including melanoma and skin cancers, infectious diseases affecting the skin (bites, bites-related infections, RMSF, Lyme, scabies, fungal infections), inflammatory dermatoses (eczema, psoriasis, rosacea), autoimmune blistering diseases (SJS/TEN), wound care and procedural skills (anesthesia, suturing, biopsies, cryotherapy), and public health concerns (bioterrorism agents, vaccines).
  • Practical clinical skills highlighted include recognizing warning signs (melanoma ABCDEs), applying appropriate topical/systemic therapies while considering patient-specific factors, and using proper wound management techniques and follow-up.
  • Several notes emphasize caution with medications (isotretinoin REMS, antibiotics during pregnancy, MRSA considerations, and steroid potency) and the importance of vaccination and public health guidelines in dermatology-related conditions.
  • Remember to tailor therapy to host factors (age, pregnancy, liver/kidney function), the extent of disease (limited vs extensive infections or inflammatory disease), and potential complications (SCID, autoimmune comorbidities, ocular involvement, and systemic spread).