History
A 55-year-old woman presents to the accident and emer-
gency department with a 6-day history of swelling of her right lower leg. She has been finding it increasingly difficult to walk due to the pain. She does not recall any preceding trauma to her leg, and she has not recently trav-elled. She has no respiratory symptoms and has not had a temperature. There is no history of previous skin problems. She is otherwise fit and well.
Examination
The right leg is hot, swollen and erythematous with indistinct borders (Fig. 71.1). Blisters are forming at the margins of the involved skin and several have broken down leaving eroded areas, which are weeping. There is no evidence of yellow crusting. The leg is tender to touch and there is pitting oedema to the knee. She has tender lymphadenopathy in the right inguinal region.
Questions
• What is the most likely diagnosis?
• What organism might you expect to be the cause?
• What management would you implement?
Medicine
This patient has cellulitis of the right leg. She has the classic signs of erythema, heat, swelling and local tenderness. Oedema blisters developed on the involved skin second-ary to acute tissue swelling. The fragile blisters rapidly de-roofed (loss of the overlying epidermis) leaving eroded areas. Her duplex scan of the right lower leg was technically challenging due to the marked oedema, so thrombus could not be ruled out. However, the clinical signs were most in keeping with infection rather than thrombus. Occasionally patients have tender regional lymphadenopathy and a fever.
A swab taken from the involved skin was negative for microorganisms, which is typical in cellulitis as the infection is in the dermis and subcutis. Blood cultures are usually nega-tive as most patients do not develop a bacteraemia. The cutaneous infection triggers an inflammatory response, which leads to the clinical signs of localized erythema, swelling, heat and tenderness. As with most cases of lower leg cellulitis there was no history of trauma or preceding skin disease in this case. Occasionally patients may have tinea pedis (fungal infection) between their toes, which can act as a portal of entry to bacteria. Cellulitis is most commonly caused by group A Streptococci or Staphylococcus aureus. Streptococcus pneumoniae can cause a very severe cellulitis of the leg, presenting with haemorrhagic bullae and necrosis, usually in immunocompromised patients or those with diabetes. S. pneumoniae may also cause cellulitis of the face as can Haemophilus influenzae type B. Patients with moderate or severe cellulitis should be treated with intravenous antibiotics, usually in hospital. Benzylpenicillin, cephalosporins or macrolides can be given. Initially patients should rest, elevate their legs and be given suitable analgesia. Topical treatment may include potassium permanganate soaks, deflation of tense blisters, applications of topical antibiotics (to prevent secondary bacterial colonization) to any eroded areas and gentle compression to reduce the oedema.
KEY POINTS
• Cellulitis is usually unilateral, the leg is hot, swollen, erythematous and tender.
• Skin swabs and blood cultures are usually negative for microbiological culture.
• Intravenous antibiotics are usually required plus elevation of the leg and light compression.
need an explanation for this answer? contact us directly to get an explanation for this answer