Ecthyma and Ecthyma Gangrenosum

Ecthyma is a condition in which the exudate or crust of a pyogenic infection involves the entire epidermis. The crust can be thick and adherent.

Overview
Ecthyma is usually the consequence of neglected impetigo caused by Staphylococcus aureus or group A streptococcus. Ecthymatous lesions can evolve from localized skin abscesses (boils) or within sites of preexisting trauma. The margin of the ecthyma ulcer can be indurated, raised, and violaceous. Untreated ecthymatous lesions can enlarge over the course of weeks or months to a diameter of 2 to 3 cm.

Staphylococcal and streptococcal ecthyma occur most commonly on the lower extremities of children, the elderly, and people who have diabetes. Poor hygiene and neglect are key elements in its pathogenesis.

Ecthyma gangrenosum is characterized by single or multiple, cutaneous or mucous membrane ulcers that are most often associated with prolonged neutropenia, Pseudomonas aeruginosa bacteremia, and other serious bacterial infections. Ecthyma gangrenosum resembles ecthyma caused by staphylococcal or streptococcal organisms. First presenting as a painless nodular lesion, it quickly develops a central hemorrhagic area that subsequently breaks down to form a large necrotic ulcer.

Differential Diagnosis:
Ecthyma can be distinguished from cutaneous anthrax in the following manner.

Ecthyma

 * Lesion is located most commonly on upper extremities (especially the hands), neck, or face


 * Systemic manifestations include fever, malaise, regional lymphadenopathy


 * Ulcer and eschar are surrounded by characteristic non-pitting edema

Cutaneous anthrax

 * Lesions are located most commonly on lower extremities


 * Systemic symptoms are unusual


 * Lesion progresses slowly

Differential Diagnosis:
Ecthyma gangrenosum can be distinguished from cutaneous anthrax in the following manner.

Ecthyma gangrenosum

 * Lesion is associated with neutropenia


 * Lesion may be associated with Pseudomonas bacteremia


 * Multiple lesions may occur

Cutaneous Anthrax

 * Ulcer and eschar are surrounded by characteristic non-pitting edema