Overview
Start with Distribution, Tempo, and the Patient
The first useful question is not “What is the rash?” It is “Where is it, how fast is it changing, and is the patient systemically unwell?” Location, symmetry, rate of spread, an...
The first useful question is not “What is the rash?” It is “Where is it, how fast is it changing, and is the patient systemically unwell?” Location, symmetry, rate of spread, and the patient’s overall appearance often narrow the differential before a diagnostic test is considered. Begin with vital signs and general appearance. Fever, tachycardia, hypotension, rigors, confusion, or an acutely ill appearance raises the priority of the assessment beyond the skin itself. Ask when the change began, whether it is enlarging, and whether pain, warmth, swelling, itch, drainage, or fever appeared first. Ask about a wound, fissure, ulcer, insect bite, recent procedure, new product, medication, antibiotic exposure, sick contact, or recurrent episodes. Diabetes, impaired circulation, chronic edema, lymphatic disease, immunosuppression, and reduced mobility can alter both risk and healing. Inspect methodically rather than focusing only on the most conspicuous area. A practical sequence is face, arms, trunk, back, legs, and feet, with additional areas exposed when symptoms or risk factors warrant. Preserve privacy, use adequate lighting, and compare corresponding sides. The feet and toe spaces may reveal a portal...