Lecture #189: Dermatologic Emergencies

What are the first priorities when evaluating a potentially emergent rash?

Assess ABCs: airway, breathing, circulation. Look for abnormal vital signs, low O2 saturation, mental status changes, mucosal involvement, systemic signs, and concerning lesion distribution.

What key history should be obtained for a dermatologic emergency?

Ask about events leading to presentation, recent exposure to foods, medications, plants, insects, allergies, current medications, and past medical history.

What is urticaria?

Urticaria is intensely pruritic, well-demarcated, pink annular swelling of the superficial dermis with central pallor and an erythematous flare border, also called wheals or hives.

What are common causes of urticaria?

Urticaria is often triggered by foods or medications, so a thorough exposure and medication history is essential.

Why can urticaria become life-threatening?

Urticaria can rarely progress to anaphylaxis, which is life-threatening and requires immediate recognition and treatment.

What is angioedema?

Angioedema is swelling of deeper dermal and subcutaneous tissues involving the tongue, lips, mouth, face, neck, or lower airway and may cause airway compromise.

What are the two major subtypes of angioedema?

Angioedema may be hereditary due to autosomal dominant C1-esterase inhibitor deficiency or acquired due to ACE inhibitors, increased bradykinin, or NSAIDs.

What is the most important management step in angioedema with airway concern?

Early intubation is critical, along with oxygen support to maintain SpO2 above 90%.

How is allergic angioedema treated?

If urticaria or allergic trigger is present, treat with antihistamines, glucocorticoids, and epinephrine, then identify and avoid the trigger.

How is hereditary angioedema treated?

Hereditary angioedema is treated with icatibant, a bradykinin inhibitor; ecallantide, a kallikrein inhibitor; C1 esterase inhibitor; or fresh frozen plasma if other treatments are unavailable.

What is erythema multiforme most commonly caused by?

Erythema multiforme is most commonly caused by infection, with herpes simplex virus as the number one infectious cause; Mycoplasma pneumoniae is another cause.

What is the pathogenesis of erythema multiforme?

EM develops after HSV infection through a cell-mediated immune response directed at viral antigens deposited in lesioned skin.

What is the classic lesion of erythema multiforme?

EM presents with targetoid lesions that have a central dusky appearance.

How do EM minor and EM major differ?

EM minor has no or only mild mucosal disease and no systemic symptoms. EM major has severe mucosal involvement and may include fever, arthralgias, conjunctivitis, and cheilitis.

What is the typical course of erythema multiforme?

Lesions appear over 3–5 days, often on palms and soles, resolve within about 14 days, usually do not scar, but may remain hyperpigmented for months.

How is erythema multiforme managed?

Treat the underlying cause, such as acyclovir for HSV-related EM; consider systemic steroids if severe, dermatology consult, and supportive care for fluids, electrolytes, infection, nutrition, thermoregulation, and pain.

What defines Stevens-Johnson syndrome versus toxic epidermal necrolysis?

SJS involves less than 10% body surface area epidermal detachment, while TEN involves more than 30% body surface area epidermal detachment.

What commonly causes SJS/TEN?

SJS/TEN is typically drug-induced, especially from sulfa antibiotics, penicillin, barbiturates, anticonvulsants such as lamotrigine, phenytoin, carbamazepine, NSAIDs, and allopurinol.

What is the pathogenesis of SJS/TEN?

SJS/TEN is mainly a drug-specific CD8+ cytotoxic T-cell-mediated reaction causing epidermal necrolysis, with possible genetic HLA predisposition.

What is Nikolsky sign?

Nikolsky sign is the ability to extend an area of epidermal detachment with gentle lateral pressure.

What are key symptoms of SJS/TEN?

After 1–3 weeks from drug exposure, patients may develop fever, arthralgia, anorexia, painful dusky red macules on the trunk that spread and coalesce, epidermal sloughing, mucous membrane involvement, tachycardia, and hypertension.

How is SJS/TEN managed?

Stop the offending drug immediately, treat like a severe burn with ICU or burn unit care, correct fluids and electrolytes, provide pain control, protect airway if needed, and use antibiotics if needed to prevent or treat sepsis.

What complications can occur after SJS/TEN?

Complications include electrolyte imbalance, multi-organ failure, infection, dehydration, ocular injury with possible vision loss, oral, pulmonary, dermatologic, genital, and psychological sequelae.

What causes staphylococcal scalded skin syndrome?

SSSS is caused by Staphylococcus aureus exfoliative toxin after skin barrier disruption, primarily affecting children.

How does staphylococcal scalded skin syndrome present?

SSSS presents with fever, irritability, purulent conjunctivitis, rhinorrhea, tender skin, erythema, edema, flaccid bullae, and desquamation over 3–5 days leaving tender raw skin.

What feature helps distinguish SSSS from SJS/TEN?

SSSS spares mucous membranes, while SJS/TEN typically involves mucous membranes.

How is staphylococcal scalded skin syndrome treated?

Treat with IV antibiotics such as nafcillin or oxacillin plus supportive care including fluids, wound care, rehydration, thermoregulation, and pain control.

What causes toxic shock syndrome?

TSS is associated with tampon use or wound, nasal, or abscess packing and is caused by Group A Streptococcus exotoxins or Staphylococcus aureus TSST-1.

What is the pathogenesis of toxic shock syndrome?

TSS is superantigen-mediated T-cell activation causing massive cytokine release, capillary leakage, hypotension, and multiorgan failure.

What clinical findings suggest toxic shock syndrome?

Findings include fever greater than 102°F, hypotension, rash, desquamation especially of palms and soles, and multisystem organ involvement.

How is toxic shock syndrome treated?

Remove the infection source immediately, give IV fluids and vasopressors if needed, and start IV antibiotics such as clindamycin plus vancomycin or nafcillin.

What causes pemphigus vulgaris?

Pemphigus vulgaris is autoimmune and caused by IgG antibodies against desmoglein 3, leading to disrupted keratinocyte adhesion and blistering.

How does pemphigus vulgaris present?

It presents with flaccid bullae that rupture, causing painful erosions prone to secondary infection, often with mucosal involvement and positive Nikolsky sign.

What biopsy finding supports pemphigus vulgaris?

Skin biopsy with direct immunofluorescence shows IgG deposits in a reticular pattern along the dermal-epidermal junction.

How is pemphigus vulgaris managed?

Admit the patient, consult dermatology, treat with plasmapheresis and IVIG, steroids and immunosuppressives, and aggressively manage fluid and electrolyte disturbances.

What is DRESS syndrome?

DRESS is drug reaction with eosinophilia and systemic symptoms, a severe drug eruption with organ involvement and peripheral eosinophilia.

What is the pathogenesis of DRESS?

DRESS is usually triggered by a drug and is associated with HLA genes and delayed type IV T-cell-mediated hypersensitivity.

What is the latency period for DRESS?

Symptoms usually begin 2–8 weeks after starting the causative drug.

What are key findings in DRESS?

Findings include extensive skin rash, fever at least 101.3°F, visceral organ involvement, lymphadenopathy, eosinophilia, facial edema, and commonly liver injury.

How does DRESS differ from SJS/TEN?

DRESS usually has mild mucosal involvement and rarely causes skin detachment, while SJS/TEN has prominent mucosal involvement and epidermal detachment.

How is severe DRESS managed?

Admit severe cases, provide organ support or ICU care, withdraw the causative medication, avoid new medications, use a long systemic corticosteroid taper, and provide fluid, electrolyte, nutritional, and gentle skin care support.

What causes meningococcemia?

Meningococcemia is a fatal systemic infection caused by the gram-negative diplococcus Neisseria meningitidis, transmitted by aerosolized droplets.

What are risk factors for meningococcemia?

Risk factors include asplenia, complement deficiency, and crowding such as dormitories or prisons.

What are classic findings of meningococcemia?

Patients may develop headache, fever, altered mental status, nausea/vomiting, myalgia, arthralgia, neck stiffness, hypotension, and petechial or purpuric rash.

How is meningococcemia treated initially?

Contact public health officials, admit to ICU, provide supportive care and IV fluids for shock, and start early IV third-generation cephalosporin plus IV vancomycin.

What is necrotizing fasciitis?

Necrotizing fasciitis is an aggressive rapidly progressive skin and soft tissue infection causing bacterial toxin release, fascia and subcutaneous tissue necrosis, and septic shock.

What are risk factors for necrotizing fasciitis?

Risk factors include diabetes, immunosuppression, trauma, liver cirrhosis, history of alcoholism, surgery, invasive procedures, or even minor procedures that break skin integrity.

What is the key clinical clue for necrotizing fasciitis?

Excruciating pain out of proportion to exam findings is the key clue; tenderness may extend beyond the erythematous border.

What physical findings suggest necrotizing fasciitis?

Findings include systemic sepsis, cellulitis, bullae, ecchymosis, paresthesia, subcutaneous emphysema, and crepitus.

How is necrotizing fasciitis managed?

Get an immediate surgery consult for debridement, keep the patient NPO, transfer to ICU, give aggressive fluids and pressors for septic shock, and start early broad-spectrum antibiotics.

What causes herpes zoster ophthalmicus?

HZO occurs when latent varicella-zoster virus reactivates in the trigeminal ganglion and affects the ophthalmic branch of CN V.

Why is herpes zoster ophthalmicus an emergency?

HZO is an ophthalmic emergency because it can cause ocular complications and vision loss.

What is Hutchinson sign in HZO?

Hutchinson sign is vesicular lesions on the nose due to involvement of the nasociliary branch of the ophthalmic branch of CN V and requires ophthalmology consult.

How does HZO rash present?

The rash is a unilateral herpetiform cluster of erythematous vesicles along the ophthalmic dermatome that does not cross the midline and evolves through pustulation, ulceration, and crusting.

How is HZO treated?

Treat early with oral antivirals such as acyclovir, pain management, and ophthalmology consult; corticosteroids may be used with ophthalmology guidance.

What causes Rocky Mountain spotted fever?

RMSF is an acute febrile tick-borne illness caused by Rickettsia rickettsii and transmitted by Dermacentor ticks, including the American dog tick and Rocky Mountain wood tick.

What is the classic triad of RMSF?

The classic triad is fever, headache, and petechial or maculopapular rash that starts at the wrists and ankles.

How is RMSF treated?

Treat immediately with doxycycline, even in children, and do not delay treatment while awaiting confirmatory lab tests.

How are burns evaluated?

Burns are evaluated by type of burn, extent using percent total body surface area such as rule of 9s, and depth including superficial, superficial partial-thickness, deep partial-thickness, full-thickness, and deeper burn injury.

How are minor burns managed?

Cool with tap water or saline, clean with mild soap and water or mild antibacterial wash, debride large blisters, leave small blisters or palm/sole blisters intact, cover with topical antibiotic and dressing, and provide pain control.

When should burns be referred to a burn center?

Severe burns greater than 10% total body surface area should be referred to a burn center for IV fluids, pain control, wound care, topical antimicrobials, and possible skin grafting.

What is Kawasaki disease?

Kawasaki disease is an immune-mediated childhood vasculitis causing panarteritis with disruption of the internal elastic lamina of arteries.

What does CRASH and Burn mean in Kawasaki disease?

CRASH stands for conjunctivitis, rash of palms and soles, adenopathy, strawberry tongue/oral mucosal changes with dry cracked lips, and hand/feet edema; Burn refers to fever greater than 5 days.

What is the major untreated complication of Kawasaki disease?

Untreated Kawasaki disease has high risk of coronary artery vasculitis, including coronary aneurysms and thrombosis.

How is Kawasaki disease treated?

Treat with IVIG within 10 days of symptoms, aspirin to prevent coronary artery aneurysms, supportive care, possible corticosteroids, and obtain echocardiogram after diagnosis.

What causes measles?

Measles, or rubeola, is caused by a highly contagious single-stranded RNA paramyxovirus transmitted by respiratory droplets.

What are the classic symptoms of measles?

Measles presents with fever and the 4 C’s: cough, conjunctivitis, coryza, and Koplik spots, followed by a maculopapular erythematous rash starting on the face and spreading to trunk and extremities.

What are major complications of measles?

Complications include encephalitis, blindness, and subacute sclerosing panencephalitis, a late CNS degenerative disease occurring 5–15 years later.

How is measles managed?

Contact public health officials, provide supportive care for uncomplicated cases, give vitamin A to prevent corneal ulceration and blindness and reduce morbidity and mortality, and prevent with MMR vaccination.