Medical library See it in the Brain
Step 3 · 4–6%
Skin & Subcutaneous Tissue
Rashes, infections, skin cancer, dangerous drug reactions, wounds and burns.
Bacterial, fungal & parasitic skin infections
In the BrainSeparate cellulitis from abscess, decide who needs MRSA coverage or admission, and match the scraping or the itch pattern to the right topical or oral drug.
Rules to know
- Warm, tender, spreading redness with no pus or abscess → nonpurulent cellulitis, usually streptococcal; cephalexin or dicloxacillin, MRSA cover not routinely needed
- Fluctuant tender nodule → abscess; incision and drainage is the key treatment; bedside ultrasound when fluctuance is unclear
- Abscess with fever, surrounding cellulitis, immunosuppression or extremes of age → after drainage add TMP-SMX, doxycycline or clindamycin for MRSA
- Purulent skin infection with sepsis or failing oral therapy → admit for IV vancomycin (or linezolid or daptomycin)
- Bright red, sharply raised plaque on the face or leg with fever → erysipelas (group A strep); penicillin, amoxicillin or cephalexin
- Leg cellulitis that keeps coming back → treat toe-web tinea, edema and skin cracks; oral penicillin prophylaxis after 3 to 4 episodes a year
- Itchy brownish redness on both lower legs, no fever → stasis dermatitis rather than cellulitis; compression and emollients
- Honey-colored crusts around a child's nose or mouth → impetigo; topical mupirocin for a few lesions, oral cephalexin when widespread
- Infant with fever, tender red skin peeling in sheets, mouth spared → staphylococcal scalded skin syndrome; admit for IV antistaphylococcal therapy
- Sore throat, then sandpaper rash and strawberry tongue → scarlet fever; penicillin or amoxicillin for 10 days
- Itchy follicular pustules a day or two after hot tub use → Pseudomonas folliculitis; self-limited, antibiotics rarely needed
- Recurrent boils in a patient or household → decolonize with nasal mupirocin and chlorhexidine washes; stop sharing towels and razors
- Painful draining swelling at the top of the buttock crease → infected pilonidal cyst; incision and drainage, definitive excision later
- Painless black eschar with marked swelling after handling animal hides or wool → cutaneous anthrax; ciprofloxacin or doxycycline, notify public health
- Ring of scale with central clearing, KOH shows hyphae → tinea corporis; topical terbinafine or an azole for 2 to 4 weeks
- Child with scaly scalp patches, broken hairs or a boggy tender mass → tinea capitis; oral griseofulvin or terbinafine
- Thick, yellow, crumbly toenails → confirm onychomycosis (KOH, PAS or culture) before 12 weeks of oral terbinafine; check baseline liver tests
- Beefy red rash in skin folds with satellite pustules → cutaneous candidiasis; topical azole or nystatin and keep dry; check glucose if recurrent
- Diaper rash in the creases with satellite papules → candida; topical antifungal plus barrier cream (irritant diaper rash spares the creases)
- Fine-scaled light or dark patches on the upper trunk, worse after summer → tinea versicolor; topical selenium sulfide or ketoconazole
- Night itching, burrows in finger webs and wrists, family also itchy → scabies; permethrin 5% neck down, repeat in 1 week, treat all contacts together
- Thick crusted scabies in a nursing-home or immunosuppressed patient → oral ivermectin plus topical permethrin; screen and treat the facility
- Live lice or nits close to the scalp → head lice; permethrin 1% or another pediculicide, repeat in 9 to 10 days; no school exclusion
- Itchy, winding raised track on the foot after a barefoot beach walk → cutaneous larva migrans; single-dose ivermectin or albendazole
- Itchy bites in rows on exposed skin after a hotel stay → bedbugs; symptom relief and professional eradication
- Nonhealing ulcer after sand-fly bites abroad → cutaneous leishmaniasis (Latin America, Africa, Middle East); biopsy and refer for treatment
- Numb hypopigmented patches with thickened peripheral nerves → leprosy (Hansen disease); skin biopsy and multidrug therapy through a specialist
Traps that cost points
- Adding MRSA coverage for every simple cellulitis→ Nonpurulent cellulitis is mostly streptococcal and a beta-lactam alone works. Reserve MRSA drugs for purulence, known MRSA or severe illness.
- Treating an abscess with antibiotics alone→ Drainage is the core therapy; antibiotics are an add-on for larger abscesses, surrounding cellulitis or systemic signs.
- Calling bilateral red, itchy lower legs cellulitis→ Cellulitis is nearly always one-sided; symmetric redness is usually stasis dermatitis, which needs compression, not antibiotics.
- Labeling severe pain and rapid spread as ordinary cellulitis→ Pain beyond the visible findings, crepitus, bullae or toxicity suggests necrotizing infection; call surgery for exploration immediately.
- Prescribing a topical antifungal for tinea capitis→ The fungus lives in the hair shaft; only oral griseofulvin or terbinafine clears it.
- Starting oral terbinafine for thick nails without a positive fungal test→ Many dystrophic nails are psoriasis or trauma; confirm fungus first because the drug carries liver risk.
- Retreating scabies because itching persists 2 weeks after permethrin→ Itch can linger 2 to 4 weeks after cure; retreat only for new burrows or new lesions.
- Applying a steroid cream to a ring-shaped scaly rash→ Steroids blur and spread tinea (tinea incognito); scrape for KOH before treating.
Skin cancer & common lesions
In the BrainKnow which lesion needs a biopsy and which kind, how melanoma depth sets the next step, and when a benign growth needs nothing at all.
Rules to know
- Mole with asymmetry, irregular border or color, or recent change → suspect melanoma, especially if wider than 6 mm; biopsy
- One mole that looks unlike the patient's others (ugly duckling) → biopsy it
- Suspected melanoma → full-thickness excisional biopsy with 1 to 3 mm margins so depth can be measured
- Large suspicious pigmented lesion on the face or an acral site → incisional or punch biopsy of the thickest area is acceptable
- Melanoma prognosis → Breslow depth is the strongest predictor; ulceration and nodal spread worsen it
- Melanoma wide excision margins → 0.5–1 cm in situ, 1 cm up to 1 mm deep, 1–2 cm for 1–2 mm, 2 cm beyond 2 mm
- Melanoma about 0.8 mm deep or more, or ulcerated → discuss sentinel lymph node biopsy
- Dark nail band with pigment spreading onto the nail fold (Hutchinson sign) → subungual melanoma; biopsy the nail matrix
- New dark lesion on a palm or sole → acral lentiginous melanoma, the commonest type in dark skin; biopsy
- Enlarging irregular brown patch on the sun-damaged face of an older adult → lentigo maligna (melanoma in situ); biopsy
- Pearly papule with rolled edges and fine vessels on the face → basal cell carcinoma; shave or punch biopsy
- Basal cell carcinoma confirmed → rarely spreads; excision, or Mohs surgery for the central face, recurrences or aggressive types
- Superficial basal cell carcinoma on the trunk → topical imiquimod or 5-fluorouracil, or curettage and electrodesiccation
- Scaly or ulcerated firm nodule on sun-exposed skin or the lower lip → squamous cell carcinoma; biopsy, then excision or Mohs
- Nonhealing ulcer in an old burn scar or chronic wound → Marjolin ulcer (SCC); biopsy the edge
- Organ transplant recipient → many and aggressive squamous cell cancers; full skin exam at least yearly and strict sun protection
- Rough, gritty scaly spots on sun-exposed skin of older adults → actinic keratosis; cryotherapy for a few, field therapy (5-FU, imiquimod, photodynamic) for many
- Actinic keratosis that thickens, hurts or ulcerates → biopsy for squamous cell carcinoma
- Waxy, stuck-on brown papules in older adults → seborrheic keratosis; benign, remove only if irritated or the diagnosis is uncertain
- Sudden eruption of many seborrheic keratoses → sign of Leser-Trélat; look for internal cancer, often gastrointestinal
- Dome-shaped nodule with a central keratin plug, grown over weeks → keratoacanthoma; excise, since it cannot be reliably told from SCC
- Firm papule on the leg that dimples inward when pinched → dermatofibroma; benign
- Mobile cyst with a central punctum → epidermoid cyst; excise intact when quiet, incise and drain when inflamed and fluctuant
- Fatty mass that is deep, over 5 cm, firm or fast-growing → MRI and referral to exclude liposarcoma
- Red raised lesion appearing in the first weeks of life → infantile hemangioma; usually regresses; oral propranolol if near eye or airway, ulcerated or disfiguring
- Congenital nevus with projected adult size over 20 cm → higher melanoma risk; dermatology follow-up
- Persistent scaly patches on the buttocks or trunk that resist steroids → mycosis fungoides (cutaneous T-cell lymphoma); biopsy, often more than once
- White oral patch that cannot be scraped off → leukoplakia; biopsy, especially with tobacco or alcohol use
- Crops of yellow papules on buttocks and extensor surfaces → eruptive xanthomas; check triglycerides because of pancreatitis risk
- Fair-skinned person aged 6 months to 24 years → counsel UV protection: broad-spectrum SPF 30 or higher reapplied every 2 hours, shade, clothing, no tanning beds
- Routine skin cancer screening in average-risk adults → evidence insufficient; examine high-risk patients and any lesion that worries the patient
Traps that cost points
- Shave biopsy of a suspected melanoma→ A superficial shave can transect the lesion and make depth impossible to stage; remove the whole lesion with narrow margins.
- Wide excision with large margins as the first step→ Diagnose first with a narrow excisional biopsy; definitive margins depend on the measured depth.
- Freezing a pigmented lesion that has not been diagnosed→ Cryotherapy destroys the tissue needed for diagnosis; biopsy anything atypical first.
- Reassuring a patient about a new dark streak in a nail→ A new or widening band, or pigment on the nail fold, needs a nail matrix biopsy.
- Calling a nonhealing ulcer in an old scar chronic irritation→ Long-standing scars can give rise to aggressive squamous cell carcinoma; biopsy any ulcer that fails to heal.
- Treating mycosis fungoides as eczema for years→ Patches in sun-protected areas that resist steroids need biopsy; repeat it if the first is nondiagnostic.
- Waiting for a fast-growing hemangioma near the eye to regress→ Lesions near the eye or airway, or ulcerating ones, need early referral and propranolol before lasting damage occurs.
Drug eruptions & blistering disease
In the BrainSpot the reactions that kill (mucosal erosions, skin sloughing, fever with eosinophilia), stop the drug, and sort blistering diseases with biopsy and immunofluorescence.
Rules to know
- Painful dusky skin, mucosal erosions and sloughing after a new drug → SJS (under 10% of body surface) or TEN (over 30%); fever, onset 1 to 3 weeks after starting
- SJS or TEN suspected → stop every possible culprit, admit to a burn or intensive care unit for wound and eye care and fluids
- Common SJS and TEN triggers → allopurinol, sulfonamides, carbamazepine, phenytoin, lamotrigine, oxicam NSAIDs, nevirapine
- Carbamazepine planned for a patient of Southeast Asian ancestry → test for HLA-B*15:02 first
- Allopurinol planned for a patient of Southeast Asian or African ancestry → consider HLA-B*58:01 testing first
- Lamotrigine started → titrate slowly, halve the dose with valproate, and stop at the first sign of rash
- Fever, rash, facial swelling, eosinophilia and liver injury after a drug → DRESS (onset 2 to 8 weeks); stop the drug, systemic steroids with a slow taper
- Patient recovering from DRESS → follow liver and kidney function, and check thyroid over the next months for autoimmune thyroiditis
- Dusky patch recurring at the same spot with each dose → fixed drug eruption (NSAIDs, sulfonamides, tetracyclines); stop it
- Itchy morbilliform rash a week into a new antibiotic, no mucosal signs → simple exanthematous eruption; stop drug, antihistamine, topical steroid
- Fever with sheets of tiny pustules days after an antibiotic → acute generalized exanthematous pustulosis; stop the drug, clears in about 2 weeks
- Rash after amoxicillin during mononucleosis → expected virus-drug eruption, not a true penicillin allergy
- Flushing and itching of the upper body during a fast vancomycin infusion → infusion reaction, not allergy; slow the rate and give an antihistamine
- Painful purple skin on breasts, thighs or abdomen days after starting warfarin → warfarin necrosis (early protein C drop); stop warfarin, vitamin K, heparin
- Exaggerated sunburn only on exposed skin after doxycycline, a thiazide or amiodarone → phototoxic reaction; sun protection or switch drug
- Redness and soreness at a vaccine injection site → expected local reaction within 1 to 2 days; not a reason to skip future doses
- Target lesions on hands and limbs after cold sores → erythema multiforme (HSV), little mucosal involvement; suppressive antivirals if recurrent
- Tender red nodules on both shins → erythema nodosum; look for strep, sarcoidosis (chest x-ray), IBD, TB, pregnancy or estrogens; NSAIDs and rest
- Older adult with tense itchy blisters on an urticarial base, mouth spared → bullous pemphigoid; biopsy with direct immunofluorescence (linear IgG and C3)
- Bullous pemphigoid treatment → superpotent topical steroid (clobetasol) even when widespread; stop a DPP-4 inhibitor if the patient takes one
- Flaccid blisters, painful mouth erosions, positive Nikolsky sign → pemphigus vulgaris; biopsy with immunofluorescence (intercellular IgG), systemic steroid plus rituximab
- Intensely itchy grouped vesicles on elbows, knees and buttocks → dermatitis herpetiformis; tTG-IgA, gluten-free diet, dapsone after checking G6PD
- Palpable purpura on the lower legs after a new drug or infection → cutaneous small-vessel vasculitis; skin biopsy, urinalysis and creatinine
- Red, scaling skin over most of the body → erythroderma; admit for fluids and temperature control, search for drug, psoriasis, eczema or lymphoma
- Blisters from minor friction since birth → epidermolysis bullosa; gentle handling, nonadhesive dressings, genetics referral
Traps that cost points
- Continuing all medications while deciding which one caused SJS→ Stop every nonessential suspect drug at once; earlier withdrawal improves survival.
- Admitting TEN to a general medical ward→ Extensive sloughing behaves like a large burn; a burn or intensive care unit manages fluids, infection and wounds.
- Calling fever, rash and eosinophilia a viral illness→ Review the drug list and check liver and kidney function; DRESS can cause organ failure weeks after the drug started.
- Labeling the mononucleosis amoxicillin rash a lifelong penicillin allergy→ Most of these patients tolerate penicillins later; avoid an allergy label that pushes them to broader drugs.
- Treating a vancomycin flushing reaction as anaphylaxis and abandoning the drug→ It is rate related; slow the infusion and premedicate if needed. True anaphylaxis brings hypotension, wheeze or angioedema.
- Starting dapsone without a G6PD level→ Dapsone can cause severe hemolysis in G6PD deficiency and methemoglobinemia in anyone; test first and monitor the blood count.
- Reaching for oral prednisone first for bullous pemphigoid in a frail elder→ Superpotent topical steroid controls disease with fewer deaths and complications than oral prednisone.
- Diagnosing pemphigus or pemphigoid from routine histology alone→ Send a perilesional biopsy for direct immunofluorescence; the staining pattern separates them.
Eczema, psoriasis, acne & other inflammatory rashes
In the BrainRecognize the pattern, match steroid strength to the site, and know the rules that govern isotretinoin and systemic therapy.
Rules to know
- Itchy flexural eczema in a child with asthma or hay fever → atopic dermatitis; daily thick emollient and a topical steroid for flares
- Atopic dermatitis on eyelids or face, or long-term control needed → topical calcineurin inhibitor (tacrolimus, pimecrolimus) or crisaborole to spare steroids
- Moderate to severe atopic dermatitis failing topicals → dupilumab or phototherapy; dupilumab commonly causes conjunctivitis
- Choosing topical steroid strength → low potency for face, folds and infants; high potency for thick plaques, palms and soles; limit duration to avoid atrophy
- Itchy rash shaped like the contact area (watch band, belt buckle, earrings) → allergic contact dermatitis, often nickel; patch test and avoid
- Streaks of vesicles after yard work → poison ivy dermatitis; potent topical steroid, or oral prednisone tapered over 2 to 3 weeks if widespread or facial
- Dry, cracked hands in a worker who washes often → irritant contact dermatitis; gloves, emollients, gentler cleansers
- Sharply bordered plaques with silvery scale on elbows, knees and scalp → plaque psoriasis; topical steroid plus a vitamin D analog
- Psoriasis over about 10% of skin, or on hands, face, genitals → phototherapy or systemic therapy (methotrexate, biologic)
- Before starting a biologic for psoriasis → screen for tuberculosis and hepatitis B, and update vaccines
- Many small droplike scaly papules after strep pharyngitis → guttate psoriasis
- Psoriasis flare after lithium, beta-blockers or stopping oral steroids → drug-triggered; avoid systemic steroids, which can provoke pustular psoriasis
- Psoriasis with nail pitting, dactylitis or joint pain → psoriatic arthritis; refer to rheumatology and favor systemic therapy
- Greasy yellow scale on scalp, eyebrows and nasolabial folds → seborrheic dermatitis; ketoconazole shampoo or cream, brief low-potency steroid
- Severe new seborrheic dermatitis in a young adult → test for HIV
- Facial flushing, papules, pustules and telangiectasias without comedones → rosacea; avoid triggers, topical metronidazole, ivermectin or azelaic acid; oral doxycycline if moderate
- Rosacea with gritty, red eyes → ocular rosacea; lid hygiene and oral doxycycline, ophthalmology if the cornea is involved
- Mild acne with comedones and a few papules → topical retinoid plus benzoyl peroxide; use a topical antibiotic only combined with benzoyl peroxide
- Moderate inflammatory acne → oral doxycycline with topical retinoid and benzoyl peroxide; stop the oral antibiotic by about 3 to 4 months
- Woman with jawline acne, irregular menses or hirsutism → combined oral contraceptive or spironolactone
- Severe nodular, scarring or treatment-resistant acne → oral isotretinoin
- Isotretinoin for anyone who can become pregnant → two negative pregnancy tests before starting, two contraception methods, monthly testing in a federal risk program
- Patient taking isotretinoin → check lipids and liver tests; avoid tetracyclines (intracranial hypertension) and vitamin A; ask about mood
- Herald patch, then oval scaly patches along skin lines of the trunk → pityriasis rosea; reassure, fades in 6 to 8 weeks; syphilis serology if sexually active
- Purple, flat-topped, itchy polygonal papules on wrists with lacy white oral lines → lichen planus; potent topical steroid; test for hepatitis C
- Hives lasting over 24 hours that burn and leave bruising → urticarial vasculitis; skin biopsy and complement levels
- Painful nodules, tunnels and scars in armpits and groin → hidradenitis suppurativa; stop smoking, lose weight, topical clindamycin, doxycycline; adalimumab or surgery if severe
- Sharply bordered white patches that glow under a Wood lamp → vitiligo; topical steroid, calcineurin inhibitor or ruxolitinib cream, narrowband UVB; check TSH
- Recurrent painful shallow mouth ulcers with a red halo → aphthous ulcers; topical steroid; with genital ulcers or uveitis consider Behçet disease
- Sweaty palms or underarms with no other symptoms → primary hyperhidrosis; aluminum chloride antiperspirant, then topical glycopyrronium, botulinum toxin or iontophoresis
- Generalized or night sweating → look for secondary causes: TB or other infection, lymphoma, hyperthyroidism, menopause, drugs
Traps that cost points
- Prescribing oral prednisone for a psoriasis flare→ Stopping it can trigger severe pustular psoriasis; use topicals, phototherapy or steroid-sparing systemic drugs.
- Applying a high-potency steroid to the face for weeks→ Facial skin thins and develops a rosacea-like eruption; use low potency briefly or a calcineurin inhibitor.
- Giving a 5-day prednisone burst for widespread poison ivy→ Short courses invite rebound; taper oral steroids over about 2 to 3 weeks.
- Pairing isotretinoin with doxycycline for extra effect→ Both raise the risk of intracranial hypertension; stop tetracyclines before starting isotretinoin.
- Using a topical antibiotic alone for acne→ Resistance develops quickly; always combine with benzoyl peroxide, and keep oral antibiotics to a few months.
- Treating rosacea with a topical steroid→ Steroids worsen rosacea and can create steroid-induced rosacea; use metronidazole, ivermectin or azelaic acid.
- Diagnosing pityriasis rosea in a sexually active adult without further testing→ Secondary syphilis can look identical, often with palm and sole lesions; check syphilis serology.
- Treating long-lasting, bruising hives with antihistamines alone→ Wheals that last over a day and leave purpura suggest vasculitis; biopsy before calling it chronic urticaria.
Burns, cold injury, bites & lacerations
In the BrainEstimate burn size and depth, start fluids and secure the airway early, know who goes to a burn center, and decide on tetanus, rabies and antibiotics for wounds and bites.
Rules to know
- Red, painful, blanching skin without blisters → superficial burn; not counted in burn size, symptomatic care
- Blistered, moist, very painful burn that blanches → superficial partial thickness; heals in 2 to 3 weeks without grafting
- Mottled, less painful partial-thickness burn with slow capillary refill → deep partial thickness; often needs excision and grafting
- Leathery, white or charred, painless skin → full-thickness burn; surgical excision and grafting
- Estimating adult burn size → rule of nines: head 9, each arm 9, front and back of trunk 18 each, each leg 18, perineum 1
- Scattered or irregular burns → the patient's palm with fingers covers about 1% of body surface
- Child's burn size → head is a larger share and legs smaller than in adults; use an age-based chart
- Adult burn of 20% or more body surface → lactated Ringer 2–4 mL × kg × %TBSA over 24 hours, half in the first 8 hours from injury
- Burn resuscitation target → urine output about 0.5 mL/kg/h in adults, 1 mL/kg/h in small children; adjust the rate hourly
- Enclosed-space fire with facial burns, soot in sputum or hoarseness → intubate early before the airway swells; check carboxyhemoglobin
- Circumferential full-thickness burn of a limb or chest → escharotomy if perfusion or ventilation is impaired
- Burn center referral → partial thickness 10% or more, any full thickness, face, hands, feet, genitals, major joints, electrical, chemical or inhalation injury
- Electrical injury → small skin marks hide deep muscle damage; ECG, CK and urine myoglobin, watch for arrhythmia and compartment syndrome
- Chemical burn → remove clothing, brush off powder, irrigate with large volumes of water; alkali burns penetrate deeper than acid
- Small burn treated in the office → cool running water, clean, leave small intact blisters, nonadherent dressing, update tetanus
- Frostbite → rewarm quickly in 37 to 39 °C water once refreezing is not a risk; analgesia, no rubbing; delay amputation until demarcation
- Itchy red-purple swollen fingers or toes after damp cold without freezing → pernio (chilblains); keep warm and dry, nifedipine if recurrent
- Clean minor wound, 3 or more prior tetanus doses → Tdap or Td only if the last dose was 10 or more years ago
- Dirty or major wound, 3 or more prior tetanus doses → booster if the last dose was 5 or more years ago
- Dirty wound with fewer than 3 prior tetanus doses or unknown history → tetanus vaccine plus tetanus immune globulin
- Simple laceration seen within about 12 to 24 hours → irrigate and close primarily; facial wounds tolerate later closure because of rich blood supply
- Dog or cat bite → irrigate well; amoxicillin-clavulanate for cat bites, hand or face bites, deep punctures, crush injury or immunocompromise
- Cat bite red and swollen within a day → Pasteurella; amoxicillin-clavulanate
- Cut over a knuckle from punching someone's mouth → clenched-fist bite; amoxicillin-clavulanate, x-ray, leave open, hand surgery to check joint and tendon
- Bite prophylaxis with penicillin allergy → doxycycline or TMP-SMX plus anaerobic cover (metronidazole or clindamycin)
- Bat, raccoon, skunk or fox bite, or bat found where someone slept → rabies immune globulin into the wound plus vaccine on days 0, 3, 7 and 14
- Bite from a healthy dog or cat that can be watched → observe the animal for 10 days; start rabies prophylaxis only if it becomes ill
- Bite from a squirrel, hamster, rat or rabbit → rabies prophylaxis almost never needed
- Tender swollen ear after blunt trauma → auricular hematoma; drain promptly and apply a pressure dressing to prevent cauliflower ear
- Scar growing beyond the original wound edges → keloid; intralesional triamcinolone; excision alone tends to recur
Traps that cost points
- Counting red, unblistered skin in the burn percentage→ Superficial burns are excluded; counting them overestimates size and leads to fluid overload.
- Giving burn fluids by formula without watching urine output→ Formulas only estimate the need; titrate hourly to urine output to avoid both under- and over-resuscitation.
- Waiting for stridor before intubating after an inhalation injury→ Airway edema builds over hours; intubate early when facial burns, soot or hoarseness are present.
- Closing a clenched-fist injury primarily→ Mouth flora seeded into the joint causes septic arthritis; irrigate, leave open and arrange hand surgery review.
- Giving tetanus immune globulin to a fully vaccinated adult with a dirty wound→ With 3 or more prior doses only a booster is needed (if 5 or more years since the last); immune globulin is for incomplete or unknown vaccination.
- Skipping rabies prophylaxis after a bat in the bedroom because no bite is visible→ Bat bites can be tiny and unnoticed; exposure while asleep counts, so give immune globulin and vaccine.
- Rubbing frostbitten skin, or rewarming it when it may refreeze→ Friction and thaw-refreeze cycles deepen tissue loss; rewarm once, in warm water.
- Putting ice on a fresh burn→ Ice deepens tissue injury and risks hypothermia; use cool running tap water for about 20 minutes.
Pressure injuries, leg ulcers, hair & nails
In the BrainStage and prevent pressure injuries, tell venous from arterial and neuropathic ulcers before choosing compression, and read hair and nail findings as clues.
Rules to know
- Intact skin with nonblanching redness over a bony area → stage 1 pressure injury; relieve pressure and reposition
- Shallow open wound with pink dermis or an intact serum blister → stage 2 pressure injury
- Full-thickness loss with fat visible but no bone, tendon or muscle → stage 3; stage 4 exposes bone, tendon or muscle
- Base hidden under slough or eschar → unstageable pressure injury; intact purple or maroon skin over a pressure point is a deep tissue injury
- Bedbound or chair-bound patient → turn at least every 2 hours, pressure-redistributing surface, float heels, control moisture, assess nutrition and Braden score
- Pressure injury with necrotic slough → debride (sharp, enzymatic or autolytic) and keep the base moist; leave a dry, stable heel eschar alone
- Deep pressure injury with exposed bone or failure to heal → probe to bone, MRI and bone biopsy for osteomyelitis; surface swabs mislead
- Shallow, weeping ulcer above the medial ankle with edema and brown staining → venous ulcer; compression and leg elevation
- Before compressing a leg ulcer → check ABI; reduce compression if 0.5 to 0.8, avoid it and refer to vascular surgery if below 0.5
- Painful punched-out ulcer on toes or lateral ankle, weak pulses → arterial ulcer (hairless shiny skin); ABI and vascular referral for revascularization
- ABI above 1.4 in a diabetic or dialysis patient → stiff, noncompressible vessels; use toe-brachial index or arterial duplex
- Painless ulcer under a metatarsal head with callus in diabetic neuropathy → neuropathic ulcer; offload (total contact cast), pare callus, check pulses
- Ulcer with a purple undermined edge that grows after debridement → pyoderma gangrenosum; look for IBD or arthritis, systemic steroids, avoid surgical debridement
- Wound slow to heal → check perfusion, infection, pressure, glucose control, nutrition, smoking and edema before changing dressings
- Round, smooth patches of hair loss with short exclamation-point hairs → alopecia areata; intralesional steroid; check thyroid if other autoimmune signs
- Diffuse shedding months after illness, surgery, childbirth or crash dieting → telogen effluvium (onset 2 to 4 months later); reassure; TSH and ferritin if no trigger found
- Gradual thinning at the crown or frontal hairline → androgenetic alopecia; topical minoxidil, finasteride for men
- Patchy hair loss with broken hairs of varying lengths and no scale → trichotillomania; habit reversal therapy
- Scarring hair loss with lost follicle openings → biopsy and dermatology referral (lupus, lichen planopilaris)
- Thinning at the temples from tight braids or ponytails → traction alopecia; loosen styles early before scarring sets in
- New nail clubbing → look for lung cancer, bronchiectasis, interstitial lung disease, cyanotic heart disease or IBD; chest imaging
- Spoon-shaped nails → iron deficiency; check ferritin
- Nail pitting with the plate lifting from the bed → nail psoriasis
- Splinter hemorrhages with fever or a new murmur → endocarditis; blood cultures
- Transverse grooves across all nails → Beau lines from a past severe illness or chemotherapy; they grow out over months
- Red, tender swelling of the nail fold → acute paronychia; warm soaks, drain if fluctuant, antistaphylococcal antibiotic if spreading
- Ingrown toenail with repeated infection → partial nail avulsion with chemical matrixectomy; soaks and a cotton wick for mild cases
- Painful blood under the nail after a crush injury → subungual hematoma; trephination for pain relief
Traps that cost points
- Calling a wound covered with eschar stage 4→ If the base cannot be seen it is unstageable; stage it only after debridement shows the depth.
- Wrapping a leg ulcer before checking pulses→ Compression on a limb with arterial disease can cause necrosis; measure the ABI first.
- Trusting a normal ABI in a long-standing diabetic→ Calcified arteries falsely raise the ABI; use toe pressures or duplex.
- Debriding a dry arterial ulcer before revascularization→ Without blood flow the wound cannot heal and may enlarge; restore perfusion first.
- Surgically debriding a rapidly enlarging ulcer that looks infected→ Pathergy makes pyoderma gangrenosum worse; suspect it with a violaceous undermined edge and treat with immunosuppression.
- Swabbing an ulcer surface to choose antibiotics→ Surface swabs grow colonizers; culture deep tissue or bone.
- Ordering a large workup for hair shedding after childbirth→ Postpartum telogen effluvium resolves on its own; reassure and recheck if it lasts beyond 6 months.
- Treating a recurrent ingrown toenail with oral antibiotics alone→ The nail edge is the cause; partial avulsion with matrix ablation prevents recurrence.