Physical Examination Findings of Ecthyma
Ecthyma presents as circular, erythematous ulcers with adherent crusts and surrounding erythematous edema, beginning as vesicles that rupture, and unlike impetigo, heals with scarring. 1
Key Distinguishing Features
Primary Lesion Characteristics
- Initial presentation: Lesions begin as vesicles that subsequently rupture 1
- Evolved appearance: Circular, erythematous ulcers with adherent crusts 1
- Surrounding tissue: Erythematous edema encircles the ulcerated areas 1
- Depth of infection: Ecthyma is a deeper infection than impetigo, extending beyond the superficial epidermis 1
Critical Diagnostic Feature
- Scarring: The hallmark distinguishing feature is that ecthyma heals with scarring, which differentiates it from impetigo 1
Important Clinical Distinction: Ecthyma vs. Ecthyma Gangrenosum
It is essential to distinguish classic ecthyma from ecthyma gangrenosum, as they are entirely different entities:
Ecthyma Gangrenosum (Different Disease Entity)
- Initial lesion: Painless erythematous papule(s) that often progress and become painful and necrotic within 24 hours 1
- Evolution: Hemorrhagic vesicle or bulla that evolves into a necrotic ulcer with eschar and surrounding erythema 2
- Central necrosis: Ulcerating lesion with central necrosis and eschar surrounded by a halo of erythema 3
- Rapid progression: Lesions can increase in size from 1 cm to >10 cm in <24 hours 1
- Location preference: Found preferentially between the umbilicus and knees 1
- Pathophysiology: Cutaneous vasculitis caused by bacterial invasion of vessel walls 1
- Associated pathogens: Classically Pseudomonas aeruginosa, but also other organisms including Staphylococcus aureus, fungi (Candida, Aspergillus, Mucor, Fusarium), and even HSV 1, 4
- Patient population: Typically occurs in immunocompromised patients, particularly those with neutropenia 1, 5, 6
Common Pitfalls to Avoid
- Do not confuse ecthyma with impetigo: While both may have crusted lesions, ecthyma is deeper and leaves scars 1
- Do not confuse ecthyma with ecthyma gangrenosum: Despite similar names, these are distinct entities with different causative organisms, pathophysiology, and clinical implications 1
- Recognize the need for cultures: Cultures of vesicle fluid, pus, erosions, or ulcers establish the causative organism (S. aureus and/or streptococci for classic ecthyma) 1