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TABLE 88.1 RASHES COMPOSED OF MACULES AND PAPULES: ETIOLOGIC CLASSIFICATION Infectious Viral Roseola infantum Rubeola Rubella Erythema infectiosum (fifth disease) Varicella (early manifestations before bullae) Epstein–Barr virus (10–15% of cases have macular or maculopapular rash) Molluscum contagiosum (papules) Dengue “Nonspecific” viral Enterovirus Echovirus Coxsackievirus Adenovirus Bacterial Scarlet fever Syphilis Disseminated gonorrhea Fungal Pityriasis versicolor Other infections Rocky Mountain spotted fever Ehrlichiosis Mycoplasma (15% of cases) Etiology uncertain but thought to be viral Pityriasis rosea Kawasaki disease Papular acrodermatitis Noninfectious Bites and infestations Insect bites Scabies Miscellaneous Drug reaction Allergic contact dermatitis Irritant contact dermatitis Papular urticaria Erythema multiforme Guttate psoriasis Pityriasis lichenoides Lichen nitidus EVALUATION AND DECISION In approaching a child with an exanthem, a careful history and full examination of all cutaneous surfaces will often be all that is required to make a diagnosis The most important historical features include the duration of the rash (acute or chronic), initial distribution, extent of spread (generalized or localized), ill contacts (including sexual partners), and any associated systemic symptoms, including fever The physical examination should include a careful systematic inspection of all mucocutaneous surfaces, with special attention paid to involvement of the oropharynx, palms and soles, extensor or flexor surfaces, scalp, and trunk TABLE 88.2 POTENTIALLY LIFE-THREATENING ILLNESSES ASSOCIATED WITH DIFFUSE MORBILLIFORM ERUPTION Rocky Mountain spotted fever Kawasaki disease Erythema multiforme Dengue fever Rubeola Ehrlichiosis Drug reaction with eosinophilia and systemic symptoms (DRESS) TABLE 88.3 GENERALIZED RASHES THAT OFTEN HAVE CHARACTERISTIC CLINICAL APPEARANCES Rubeola Erythema infectiosum (fifth disease) Hand–foot–mouth disease (coxsackievirus A16) Molluscum contagiosum Scarlet fever Pityriasis versicolor Pityriasis rosea Roseola infantum Insect bites Erythema multiforme Stevens–Johnson syndrome Drug reaction with eosinophilia and systemic symptoms For patients with widespread rash who appear ill, consider drug hypersensitivity reaction, or severe viral or bacterial infection Figure 88.12 may help with an approach to morbilliform/mixed macular and papular eruptions For patients who not appear ill, certain exanthems will have distinctive patterns that make the diagnosis readily apparent Erythema multiforme, rubella, coxsackievirus infections ( Fig 88.14 ), erythema infectiosum ( Fig 88.15A,B ), scarlet fever, varicella, MC ( Fig 88.16 ), tinea versicolor ( Fig 88.17 ), pityriasis rosea ( Fig 88.18 ), and roseola all have recognizable clinical appearances Many of these illnesses have characteristic distributions or associated signs and symptoms that aid in their diagnoses If the pattern of the rash does not evoke immediate recognition from the examiner, a more methodical approach is indicated, as outlined in Figure 88.19