Table 1: Differential diagnoses of impetigo contagiosa [9].
| Diagnosis | Distinguishing features |
| Atopic dermatitis | Chronic or relapsing pruritic lesions and abnormally dry skin; there is marked lichenification on the flexural areas which distinguishes it from impetigo |
| Candidiasis | Erythematous papules or red, moist plaques; unlike impetigo, this disease is usually confined to the mucosal surfaces and 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 penetrate into hair follicles |
| Ecthyma | Crusted lesions that cover an ulceration, unlike impetigo in which there is an erosion only. The ulceration 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; there may be an associated urticaria, which is not typical for impetigo |
| Pemphigus foliaceus | 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 and pustules |
| Varicella | Thin-walled vesicles on an erythematous base that start on trunk and spread to face and extremities; vesicles break and crusts form. Unlike impetigo, in varicella the lesions are in different stages |