Life-threatening dermatoses.

Although rare, life-threatening dermatoses encompass various inflammatory, infectious, vasculitic/vasculopathy, paraneoplastic, and neoplastic skin diseases. Complications include skin barrier dysfunction, secondary infection, and internal organ involvement. Skin signs may serve as a critical window into systemic disease. Life-threatening dermatoses are typically associated with "red flag" clinical signs or symptoms, which inform the dermatologist about the severity of the disease and mandate a thorough history, review of systems, physical examination, and laboratory evaluation. This contribution highlights severe cutaneous adverse reactions, infections, vasculitides and vasculopathies, and paraneoplastic eruptions. Dermatologists should recognize life-threatening dermatoses and have a framework for rapid diagnosis and management.