Acute limb swelling 2 – Cellulitis

Mrs. Sarah Jones, 68-year-old female, presents to the Emergency Department with a 2-day history of painful, red, swollen right lower leg. She noticed a small cut on her shin after gardening 3 days ago. She feels generally unwell with fevers and chills.

How would you approach this patient?

When assessing a patient with suspected cellulitis, I would start by taking a focused history of the presenting complaint. I would ask about the onset and progression of the swelling. I would ask for any points of entry such as cuts, scratches, or insect bites. I would enquire about systemic symptoms like fever, chills, or general malaise, and whether they’ve attempted any treatment already.

I would assess for any potential risk factors in her past medical hx specifically looking for any history of diabetes, obesity, HTN, previous cellulitis. After this I would go on to do an A to E.

(Mention the whole A to E and focus on C and E)

(When examining the affected area, I would carefully note and mark the extent of erythema, assess for local warmth and tenderness, and look for lymphangitis or lymphadenopathy. Any wounds or discharge should be documented. It’s essential to compare with the contralateral limb and examine for signs of underlying venous insufficiency.)

(Crucially, I would look for red flag signs suggesting necrotizing fasciitis, such as disproportionate pain, crepitus, or dusky skin changes. I would check peripheral pulses and perform a basic neurological assessment of the affected limb.)

Examiner

These are the examination findings:

• Temperature 38.5°C, HR 98, BP 128/78, RR 18, O2 sats 97% on air
• Well-demarcated erythema on right lower leg
• Warm, tender to touch
• Superficial scratch visible
• No fluctuance or crepitus
• No lymphadenopathy
• Pedal pulses present

Examiner – What are the key differential diagnoses you would consider?

• Deep Vein Thrombosis
• Erysipelas (more superficial infection)
• Necrotizing fasciitis
• Acute lipodermatosclerosis
• Ruptured Baker’s cyst
• Should mention distinguishing features of each

Examiner – How would you manage this patient?

As my suspicion is high for a DVT, I would admit the patient and do the following investigations:

• Blood tests:
  • FBC, U&Es, CRP
  • Blood cultures if febrile
  • Blood glucose
• Wound swab if discharge present
• Mark extent of erythema
• Consider imaging if:
  • Suspicion of abscess
  • Necrotizing fasciitis suspected
  • Deep tissue infection

In terms of treatment I would start the patient on:

• IV antibiotics (Flucloxacillin first line)
• Consideration of MRSA coverage if risk factors
• Elevation of affected limb
• Analgesia
• Regular monitoring of affected area
• Blood glucose control
• DVT prophylaxis

Examiner – The patient asks about duration of treatment and follow-up. What would you advise?

• Usually 7-10 days total
• Switch to oral when:
  • Clinically improving
  • Afebrile for 24-48 hours
  • Improving inflammatory markers
• Follow-up in primary care
• Skin care advice
• Prevention strategies

Examiner – What features would worry you for necrotizing fasciitis?

• Severe pain disproportionate to signs
• Rapid spread
• Crepitus
• Skin changes (dusky/purple/bullae)
• Systemic toxicity
• Failed response to antibiotics
• Should mention this is a surgical emergency