Ecthyma: causes, symptoms, diagnosis, and treatment

Ecthyma, also known as deep impetigo, is a deep inflammation with necrosis and ulceration, leaving scars and pigmentation after healing.


Causes

The pathogens are mostly β hemolytic streptococcus, merely staphylococcus aureus, or combined infections. In addition, pseudomonas aeruginosa, Escherichia coli, and other saprophytic bacteria are also found. Malnutrition, infirmity, and poor personal hygiene are often inducements. This disease is often secondary to scabies, varicella, diabetes, and insect bites.


Signs and Symptoms

Pea sized blisters or pustules occur initially, with basal inflammatory infiltration, expanding continuously, leading to necrotic center, forming dark brown dirty crusts. In severe cases, thick crusts are like oyster shell. Pus is discharged from the surrounding area when pressed. It is not easy to remove the crusts. After removal of crusts, sharply demarcated, round or oval ulcers can be seen, with a steep periphery and a hard base, with grayish green purulent secretions. Ulcers usually heal after incrustation, persisting for 2 - 4 weeks. Skin lesions are varying in number, often from several to dozens, mainly in the lower limbs and buttocks, occasionally in other sites. Subjective burning sensation, pruritus, and pain are present. Generally systemic symptoms are absent. Under the conditions of dozens of skin lesions, debilitated health, and low body's immune function, skin lesions develop rapidly, forming deep necrotizing ulcers, known as ecthyma gangrenosum or ecthyma cachecticorum, mostly in infants and young children, with poor prognosis, often accompanied by sepsis, pneumonia, and death.


Histopathology

Obvious inflammatory reaction in the dermis is visible. Vasodilation, thrombosis, and necrosis of the surrounding connective tissue result in superficial ulcers. The ulcers are covered by crusts composed of dried fibrin and keratin, and necrotic epithelial cells and white blood cells are beneath the crusts. Epidermal edema and acanthosis are visible at the margin of ulcers. Some cocci in the upper crusts can be seen in Gram stain.


Diagnosis

On the basis of clinical manifestations, such as blisters, pustules, necrosis, and ulcers, it is not difficult to diagnose

Differential diagnosis

Impetigo is manifested by only blisters, pustules, and scars, without ulceration.

Papulonecrotic tuberculid is characterized by some scattered small papules, pustules, and crusts, as well as pea sized small ulcers after removal of crusts, without deep penetrating ulcers.

Allergic vasculitis or hypersensitivity vasculitis is characterized by purpura, papules, nodules, and ulcers, as well as fibrinoid degeneration and necrotizing vasculitis in vascular walls in pathological examinations.


Treatment

Systemic treatment

Antibiotics, such as penicillin, cloxacillin sodium, clindamycin, or erythromycin, can be used.

Topical treatment

Immersion or wet compress with 1:5000 potassium permanganate solution or 0.1% ethacridine solution can be applied to patients with thick crusts. Topical mupirocin ointment, fusidic acid ointment, or 0.5% ofloxacin cream can be selected.