If you think you or your kid has school sores you should see your docotor. A impetigo diagnosis is usually straightforward from the typical look of the skin infection.
Sometimes school sores can be confused with other skin conditions such as shingles, fungal skin infections or cold sores. If there is any doubt, your doctor might take a swab from the affected area. The swab will be tested for impetigo at a laboratory.
Doctors usually diagnose impetigo by considering signs and symptoms and medical history and looking at the distinctive sores. Your doctor will likely ask about any recent cuts, scrapes or insect bites to the affected area.
A culture may be necessary to confirm the impetigo diagnosis or to rule out another cause. During this impetigo test, your doctor uses a sterile swab to gently remove a small bit of pus or drainage from one of the sores. The sample is then cultured in a laboratory for the presence of bacteria.
Differential Diagnosis of Nonbullous Impetigo:
Atopic dermatitis - Chronic or relapsing pruritic lesions and abnormally dry skin; flexural lichenification is common in adults; facial and extensor involvement is common in children
Candidiasis - Erythematous papules or red, moist plaques; usually confined to mucous membranes or intertriginous areas
Contact dermatitis - Pruritic areas with weeping on sensitized skin that comes in contact with haptens (e.g., poison ivy)
Dermatophytosis - Lesions may be scaly and red with slightly raised “active border” or classic ringworm; or may be vesicular, especially on feet
Discoid lupus erythematosus - Well-defined plaques with adherent scale that penetrates into hair follicles; peeled scales have “carpet tack” appearance
Ecthyma - Crusted lesions that cover an ulceration rather than an erosion; may persist for weeks and may heal with scarring as the infection extends to the dermis
Herpes simplex virus - Vesicles on an erythematous base that rupture to become erosions covered by crusts, usually on the lips and skin
Insect bites - Papules usually seen at site of bite, which may be painful; may have associated urticaria
Pemphigus foliaceus - Serum and crusts with occasional vesicles, usually starting on the face in a butterfly distribution or on the scalp, chest, and upper back as areas of erythema, scaling, crusting, or occasional bullae
Scabies - Lesions consist of burrows and small, discrete vesicles, often in finger webs; nocturnal pruritus is characteristic
Sweet's syndrome - Abrupt onset of tender or painful plaques or nodules with occasional vesicles or pustules
Varicella - Thin-walled vesicles on an erythematous base that start on trunk and spread to face and extremities; vesicles break and crusts form; lesions of different stages are present at the same time in a given body area as new crops develop
Differential Diagnosis of Bullous Impetigo:
Bullous erythema multiforme - Vesicles or bullae arise from a portion of red plaques, 1 to 5 cm in diameter, on the extensor surfaces of extremities
Bullous lupus erythematosus - Widespread vesiculobullous eruption that may be pruritic; tends to favor the upper part of the trunk and proximal upper extremities
Bullous pemphigoid - Vesicles and bullae appear rapidly on widespread pruritic, urticarial plaques
Herpes simplex virus - Grouped vesicles on an erythematous base that rupture to become erosions covered by crusts, usually on the lips and skin; may have prodromal symptoms
Insect bites - Bullae seen with pruritic papules grouped in areas in which bites occur
Pemphigus vulgaris - Nonpruritic bullae, varying in size from 1 to several centimeters, appear gradually and become generalized; erosions last for weeks before healing with hyperpigmentation, but no scarring occurs
Stevens-Johnson syndrome - Vesiculobullous disease of the skin, mouth, eyes, and genitalia; ulcerative stomatitis with hemorrhagic crusting is most characteristic feature
Thermal burns - History of burn with blistering in second-degree burns
Toxic epidermal necrolysis - Stevens-Johnson–like mucous membrane disease followed by diffuse generalized detachment of the epidermis
Varicella - Thin-walled vesicles on an erythematous base that start on trunk and spread to face and extremities; vesicles break and crusts form; lesions of different stages are present at the same time in a given body area as new crops develop