A 58-year-old man with a 20-year history of psoriasis presents to the emergency department with acute onset of diffuse erythema involving >90% of his body surface area, marked scaling, and fever. Examination reveals generalized lymphadenopathy and hepatomegaly. The structure marked **A** in the diagram represents the diffuse generalized erythema involving >90% of BSA. Which of the following is the MOST IMMEDIATE life-threatening complication directly attributable to the extent of skin involvement shown at **A**?

Explanation

## Why "Acute high-output cardiac failure secondary to increased cutaneous blood flow and protein loss leading to fluid retention" is right Erythroderma involving >90% BSA (marked **A**) creates a dermatologic emergency due to massive disruption of the skin barrier and vasodilation. The extensive erythema causes shunting of blood to the skin surface to dissipate heat, dramatically increasing cutaneous blood flow. Simultaneously, the damaged epidermis permits massive protein and fluid loss, leading to hypoalbuminemia and fluid sequestration in tissues. The combination of high-output demand (increased skin perfusion) and reduced circulating volume (protein/fluid loss) triggers compensatory fluid retention and increased cardiac output, precipitating high-output cardiac failure. This is one of the most immediately life-threatening systemic complications of erythroderma and requires urgent hospitalization and fluid/electrolyte replacement. (Robbins 10e Ch 25) ## Why each distractor is wrong - **Localized bacterial infection limited to areas of active scaling and exfoliation**: While S. aureus sepsis is a recognized complication of erythroderma due to loss of skin barrier function, it is NOT the most immediate life-threatening complication. Sepsis typically develops over hours to days, whereas hemodynamic decompensation from the massive surface area involvement (>90% BSA) can occur acutely. Additionally, the infection is not "localized" — it is a systemic risk due to generalized barrier loss, not limited to scaling areas. - **Chronic renal insufficiency from prolonged electrolyte imbalance**: Electrolyte disturbances (sodium, potassium, chloride loss through exudation) are indeed serious in erythroderma, but chronic renal insufficiency is a late complication requiring prolonged disease. The acute life-threatening complication is thermoregulatory failure and high-output cardiac failure, not chronic kidney disease. - **Malignant transformation of psoriatic plaques to squamous cell carcinoma**: Psoriasis itself does not undergo malignant transformation to SCC. However, erythroderma CAN be a presenting manifestation of underlying cutaneous T-cell lymphoma (Sézary syndrome), but this is a pre-existing malignancy revealed by erythroderma, not a transformation caused by the erythroderma. This is not the most immediate complication of the extensive skin involvement shown at **A**. **High-Yield:** Erythroderma >90% BSA is a dermatologic emergency — the triad of massive fluid/protein loss, cutaneous vasodilation, and thermoregulatory failure precipitates high-output cardiac failure, requiring immediate hospitalization, aggressive fluid/electrolyte replacement, and temperature management. [cite: Robbins 10e Ch 25]