Systematic dermatological assessment uses standardized terminology: Primary lesions (from normal skin): macule (flat, < 1 cm), patch (flat, > 1 cm), papule (raised, < 1 cm), plaque (raised, > 1 cm), nodule (deep, > 1 cm), vesicle (fluid, < 1 cm), bulla (fluid, > 1 cm), pustule (pus-filled), wheal (edematous/transient). Secondary lesions from evolution: scale, crust, erosion, ulcer, excoriation, fissure, lichenification. Distribution provides diagnostic clues: dermatomal = herpes zoster; photodistributed = SLE, drug photosensitivity; extensor = psoriasis; flexural = atopic dermatitis; palms/soles = secondary syphilis, RMSF, hand-foot-mouth, SJS/TEN. Life-threatening emergencies: SJS/TEN (epidermal detachment from drugs — sulfonamides, allopurinol, anticonvulsants), necrotizing fasciitis (pain out of proportion), meningococcemia (petechial/purpuric rash with sepsis).