Karnataka PGET Dermatology MCQ Answer 4

• Ecthyma gangrenosum (EG) is a well-recognized cutaneous infection most commonly associated with a Pseudomonas aeruginosa bacteremia.
  
• EG usually occurs in patients who are critically ill and immunocompromised. Impaired humoral or cellular immunity leads to increased susceptibility to infections with P aeruginosa or other pathogens.
  
• The lesions of EG result from perivascular bacterial invasion of arteries and veins in the dermis and subcutaneous tissues, producing a necrotizing vasculitis. Perivascular involvement can occur by hematogenous seeding of the skin in bacteremic patients or by direct inoculation through the skin in nonbacteremic patients.
  
• EG typically occurs in patients who are immunocompromised, including patients with hematologic malignancies, immunodeficiency syndromes, severe burns, malnutrition, recent chemotherapy, immunosuppressive therapy, and diabetes mellitus.
  
• Primary cutaneous lesions of EG initially appear as painless round erythematous macules that rapidly become pustular with surrounding erythema. A hemorrhagic focus appears in the center, forming a bulla. As the hemorrhagic bulla spreads peripherally, it evolves into a gangrenous ulcer with black/gray eschar surrounded by an erythematous halo. The transformation of an early lesion to a necrotic ulcer may occur in as little as 12 hours.
• Distribution of lesions: EG may appear at any location on the body; however, it commonly appears on the gluteal or perineal region (57%), extremities (30%), trunk (6%), and face (6%).
  
• Treatment of EG requires the use of antipseudomonal penicillins, aminoglycosides, fluoroquinolones, third-generation cephalosporins, or aztreonam. While awaiting results, an antipseudomonal penicillin (piperacillin) should be used in conjunction with an aminoglycoside (gentamicin).

Category: Karnataka PGET 2007 MCQs