What is Impetigo?
Impetigo is a highly contagious bacterial skin infection that primarily affects children. It is typically caused by
Staphylococcus aureus or
Streptococcus pyogenes. Characterized by red sores that can rupture, ooze, and form a yellow-brown crust, impetigo can occur anywhere on the body but most commonly affects the face, arms, and legs.
Histological Features of Impetigo
The histological examination of impetigo primarily reveals a superficial infection confined to the epidermis. Key histological features include: Presence of
neutrophils in the epidermis and the formation of subcorneal pustules.
Spongiosis, or intercellular edema, which can lead to vesicle formation.
Acantholysis, or loss of intercellular connections, leading to the breakdown of epidermal cells.
Formation of crusts composed of dried serum, inflammatory cells, and bacterial colonies.
Absence of significant involvement of the
dermis, indicating the superficial nature of the infection.
Pathogenesis
The pathogenesis of impetigo involves the invasion of bacteria into the superficial layers of the epidermis.
Staphylococcus aureus produces exfoliative toxins that cleave desmoglein-1, a protein critical for cell-to-cell adhesion in the epidermis. This leads to the formation of blisters and subsequent pustules.
Streptococcus pyogenes can also activate inflammatory pathways, contributing to the development of lesions and pustules.
Diagnosis
Diagnosis of impetigo can often be made clinically based on the characteristic appearance of the lesions. However, histological examination can provide definitive confirmation. A biopsy of the lesion will show the aforementioned histological features. Additionally,
bacterial cultures can identify the specific pathogen responsible for the infection.
Treatment
Treatment of impetigo typically involves topical or oral antibiotics.
Topical antibiotics like mupirocin or fusidic acid are often effective for localized infections. More extensive cases may require oral antibiotics such as cephalexin or dicloxacillin. Proper hygiene and wound care are also crucial to prevent the spread of infection.
Prognosis and Complications
With appropriate treatment, impetigo generally has an excellent prognosis, and lesions usually heal without scarring. Potential complications include post-streptococcal glomerulonephritis, though this is rare. It is important to treat impetigo promptly to prevent the spread to others and to avoid potential complications.
Conclusion
Impetigo is a common superficial bacterial infection that primarily affects the epidermis. Histological examination reveals key features such as neutrophilic infiltration, spongiosis, and acantholysis. Understanding the histology of impetigo aids in accurate diagnosis and effective treatment, ensuring a good prognosis and reducing the risk of complications.
