Ecthyma gangrenosum

• Ecthyma gangrenosum is a dermatologic manifestation of severe infection with P. aeruginosa
  • has been considered to be a pathognomonic sign of P. aeruginosa bacteremia that occurs in up to 6% of patients with systemic infection
  • however clinically similar lesions, however, have been reported secondary to other infections e.g. E. coli, Aspergillus niger, and in patients with Candida sepsis
  • occurs predominantly if not exclusively in immunocompromised patients
    • predisposing factors include malnutrition, malignancy (especially hematological), medications (cancer chemotherapy, systemic corticosteroids, antibiotics), widespread burns, cystic fibrosis, poorly controlled diabetes mellitus, neutropaenia or pancytopaenia as a result of illness or medications
  • lesion of ecthyma gangrenosum typically begins as a red or purpuric macule
    • evolves into a hemorrhagic bulla - bulla subsequently ruptures to form a gangrenous, suppurative ulcer with a black eschar and an erythematous rim
      • lesions may be solitary or multiple
      • in bacteraemic patients commonly lesions occur in apocrine areas, but lesions also may be scattered elsewhere on the trunk and extremities
    • primary cutaneous infections caused by direct inoculation occur predominantly in apocrine areas - may occasionally occur at wound sites
      • this pattern of infection occasionally begins as folliculitis with rapid evolution into more classical ecthyma gangrenosum lesions
      • in echyma gangrenosum associated with bacteraemia there is a male predominance. There is a female predominance in patients with the primary cutaneous form of infection
  • management
    • requires prompt diagnosis and initiation of treatment
      • consider the diagnosis when a hemorrhagic bulla or gangrenous ulcer is noted on the skin of an immunocompromised patient
        • performa a skin biopsy for histopathologic evaluation and for bacterial culture and antibiotic susceptibility testing
        • obtain blood cultures
        • empirical intravenous antibiotic therapy should be initiated because a delay in the initiation of therapy is associated with a worse prognosis
          • antimicrobial regimen of choice is an antipseudomonal penicillin combined with an aminoglycoside
  • prognosis is often poor

Reference:

1. Wortman PD. Bacterial infections of the skin. Current Problems in Dermatology 1993; 5 (6):197-224.