skip to main content

Necrotising Fasciitis Clinical Sign — SCE Infectious Diseases MCQ

Instant feedback + full explanation. One question, done properly.

EasyInfection Prevention & ControlNecrotising Fasciitis Clinical SignSCE Infectious Diseases

A 35-year-old man presents to the emergency department with a 12-hour history of rapidly progressive right leg swelling, severe pain out of proportion to clinical findings, bronze-grey skin discolouration, and crepitus. He had a minor laceration on the leg 3 days ago. WCC is 28 × 10⁹/L, CRP 450 mg/L, lactate 5.2 mmol/L. What clinical sign is most specific for necrotising fasciitis vs simple cellulitis?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — Pain out of proportion to clinical appearance — this is the earliest and most sensitive clinical sign of necrotising fasciitis

Pain disproportionate to the visible skin changes is the hallmark early clinical feature of necrotising fasciitis. Other suggestive features include: rapidly spreading erythema, bronze/grey skin discolouration, bullae, crepitus (gas gangrene), systemic toxicity, and cutaneous anaesthesia (nerve destruction). The LRINEC score can aid clinical decision-making but should not delay surgical referral. Emergency surgical exploration is the definitive diagnostic and therapeutic intervention — imaging should not delay surgery if clinical suspicion is high. Mortality increases by ~25% for every 6 hours of surgical delay.

Reference: NICE NG141 2019 – SSTI; WHO 2023 – Necrotising fasciitis