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Emergency And Acute Medicine – Rash
Rash refers to abnormal skin lesions resulting from inflammatory, infectious, vascular, autoimmune, allergic, or malignant processes. In emergency medicine, careful attention to morphology, distribution, associated systemic symptoms, and evolution is essential. Warning signs of a dermatologic emergency include erythroderma, blistering or desquamation, purpura, skin pain out of proportion to findings, and systemic symptoms such as fever or hypotension.
Rashes are classified by morphology. Vesiculobullous lesions are fluid-filled elevations caused by disruption of epidermal or dermal integrity and include vesicles (<5 mm) and bullae (>5 mm). Serious causes include toxic epidermal necrolysis, Stevens–Johnson syndrome, pemphigus vulgaris, bullous pemphigoid, disseminated herpes infections, and severe drug reactions. Purpura and petechiae result from vascular or hemostatic failure and do not blanch with pressure; life-threatening causes include meningococcemia, disseminated intravascular coagulation, Rocky Mountain spotted fever, and vasculitis. Erythema is caused by superficial vascular dilation and blanches with pressure; erythroderma involves ≥90% of body surface area and may occur with toxic shock syndrome, severe drug reactions, psoriasis, or cutaneous lymphoma. Papulosquamous eruptions include psoriasis, pityriasis rosea, secondary syphilis, and dermatitis. Nodules may represent granulomatous disease, infection, panniculitis, cysts, or malignancy.
History should address age, immune status, medication changes, recent infections, travel, tick exposure, environmental factors, sick contacts, and prior similar episodes. Associated symptoms such as fever, pruritus, arthralgias, abdominal pain, or prodromal viral symptoms help narrow the diagnosis. A detailed drug history is critical, particularly for possible drug reactions with eosinophilia and systemic symptoms (DRESS) or Stevens–Johnson syndrome.
Physical examination must assess vital signs and systemic stability. Fever, hypotension, respiratory distress, or altered mental status suggest a potentially life-threatening condition. Skin pain disproportionate to findings raises concern for necrotizing infection. Lymphadenopathy may suggest systemic drug reaction or infection. Primary lesion type, distribution (central vs peripheral, mucosal involvement, palm/sole involvement), and secondary changes such as scaling, crusting, ulceration, or necrosis should be documented.
Workup depends on severity and suspected cause. Patients with fever or systemic symptoms require laboratory evaluation including CBC with differential, electrolytes, renal function, and blood cultures when infection is suspected. Purpuric rashes require platelet count and coagulation studies to evaluate for thrombocytopenia or DIC. Viral lesions may be evaluated with PCR or direct fluorescent antibody testing. Suspected syphilis warrants rapid plasma reagin testing. Autoimmune conditions may require inflammatory markers and specialized serologies in consultation with specialists. Skin scrapings may identify fungal infection or scabies. Skin biopsy under dermatologic consultation may be required for unclear or severe cases. The Nikolsky sign, in which lateral pressure causes epidermal sloughing, suggests epidermal detachment disorders.
Management prioritizes stabilization and early treatment of life-threatening conditions. Patients with petechiae or purpura and fever should receive immediate empiric antibiotics covering meningococcemia and Rocky Mountain spotted fever. Diffuse erythema with hypotension should prompt treatment for toxic shock syndrome. Disseminated bullous or exfoliative disorders should be managed similarly to severe burns, with attention to fluid balance, wound care, and infection prevention. Symptomatic treatment for pruritus includes antihistamines such as diphenhydramine or hydroxyzine. Systemic corticosteroids are reserved for confirmed allergic reactions, steroid-responsive disease, or specialist guidance. Severe allergic reactions require antihistamines, corticosteroids, and epinephrine if airway compromise is present.
Admission is indicated for patients with significant bullous or exfoliative disease, purpura with systemic symptoms, erythroderma with instability, or evidence of sepsis. Patients with limited, stable lesions and no systemic signs may be discharged with close follow-up. Clear return precautions should include worsening rash, spreading redness, increasing pain, joint pain, fever, severe headache, confusion, or signs of anaphylaxis such as difficulty breathing or tongue swelling.
Rapid progression of a rash with systemic symptoms signals potential emergency. Empiric antibiotics are critical in febrile patients with purpura or erythroderma and hemodynamic instability. Hyperpigmented scaly papules on the palms and soles should prompt evaluation for secondary syphilis. Careful assessment and timely intervention are essential to prevent morbidity and mortality.
Rash refers to abnormal skin lesions resulting from inflammatory, infectious, vascular, autoimmune, allergic, or malignant processes. In emergency medicine, careful attention to morphology, distribution, associated systemic symptoms, and evolution is essential. Warning signs of a dermatologic emergency include erythroderma, blistering or desquamation, purpura, skin pain out of proportion to findings, and systemic symptoms such as fever or hypotension.
Rashes are classified by morphology. Vesiculobullous lesions are fluid-filled elevations caused by disruption of epidermal or dermal integrity and include vesicles (<5 mm) and bullae (>5 mm). Serious causes include toxic epidermal necrolysis, Stevens–Johnson syndrome, pemphigus vulgaris, bullous pemphigoid, disseminated herpes infections, and severe drug reactions. Purpura and petechiae result from vascular or hemostatic failure and do not blanch with pressure; life-threatening causes include meningococcemia, disseminated intravascular coagulation, Rocky Mountain spotted fever, and vasculitis. Erythema is caused by superficial vascular dilation and blanches with pressure; erythroderma involves ≥90% of body surface area and may occur with toxic shock syndrome, severe drug reactions, psoriasis, or cutaneous lymphoma. Papulosquamous eruptions include psoriasis, pityriasis rosea, secondary syphilis, and dermatitis. Nodules may represent granulomatous disease, infection, panniculitis, cysts, or malignancy.
History should address age, immune status, medication changes, recent infections, travel, tick exposure, environmental factors, sick contacts, and prior similar episodes. Associated symptoms such as fever, pruritus, arthralgias, abdominal pain, or prodromal viral symptoms help narrow the diagnosis. A detailed drug history is critical, particularly for possible drug reactions with eosinophilia and systemic symptoms (DRESS) or Stevens–Johnson syndrome.
Physical examination must assess vital signs and systemic stability. Fever, hypotension, respiratory distress, or altered mental status suggest a potentially life-threatening condition. Skin pain disproportionate to findings raises concern for necrotizing infection. Lymphadenopathy may suggest systemic drug reaction or infection. Primary lesion type, distribution (central vs peripheral, mucosal involvement, palm/sole involvement), and secondary changes such as scaling, crusting, ulceration, or necrosis should be documented.
Workup depends on severity and suspected cause. Patients with fever or systemic symptoms require laboratory evaluation including CBC with differential, electrolytes, renal function, and blood cultures when infection is suspected. Purpuric rashes require platelet count and coagulation studies to evaluate for thrombocytopenia or DIC. Viral lesions may be evaluated with PCR or direct fluorescent antibody testing. Suspected syphilis warrants rapid plasma reagin testing. Autoimmune conditions may require inflammatory markers and specialized serologies in consultation with specialists. Skin scrapings may identify fungal infection or scabies. Skin biopsy under dermatologic consultation may be required for unclear or severe cases. The Nikolsky sign, in which lateral pressure causes epidermal sloughing, suggests epidermal detachment disorders.
Management prioritizes stabilization and early treatment of life-threatening conditions. Patients with petechiae or purpura and fever should receive immediate empiric antibiotics covering meningococcemia and Rocky Mountain spotted fever. Diffuse erythema with hypotension should prompt treatment for toxic shock syndrome. Disseminated bullous or exfoliative disorders should be managed similarly to severe burns, with attention to fluid balance, wound care, and infection prevention. Symptomatic treatment for pruritus includes antihistamines such as diphenhydramine or hydroxyzine. Systemic corticosteroids are reserved for confirmed allergic reactions, steroid-responsive disease, or specialist guidance. Severe allergic reactions require antihistamines, corticosteroids, and epinephrine if airway compromise is present.
Admission is indicated for patients with significant bullous or exfoliative disease, purpura with systemic symptoms, erythroderma with instability, or evidence of sepsis. Patients with limited, stable lesions and no systemic signs may be discharged with close follow-up. Clear return precautions should include worsening rash, spreading redness, increasing pain, joint pain, fever, severe headache, confusion, or signs of anaphylaxis such as difficulty breathing or tongue swelling.
Rapid progression of a rash with systemic symptoms signals potential emergency. Empiric antibiotics are critical in febrile patients with purpura or erythroderma and hemodynamic instability. Hyperpigmented scaly papules on the palms and soles should prompt evaluation for secondary syphilis. Careful assessment and timely intervention are essential to prevent morbidity and mortality.
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