Dermatology
Abdullah Al-Anazi
Elena Pope
Introduction
Rashes presenting to the emergency department may be classified as follows:
Morbilliform eruptions (maculopapular)
Vesiculobullous eruptions
Pruritic eruptions
Life-threatening rashes
Fungal infections
Petechiae and purpura
Morbilliform Eruptions (Maculopapular Rashes)
Differential Diagnosis
Viral: measles, rubella, roseola, erythema infectiosum
Drug eruptions (usually antibiotics, anticonvulsants)
Bacterial: scarlet fever
Kawasaki disease
Rocky Mountain Spotted Fever
Roseola Infantum
Caused by human herpesvirus 6
Common age 6 months to 2 years
Well-looking child despite high fever
Fever persists for 3-4 days
Macular or maculopapular rash appears on 3rd-4th day of illness as fever subsides
May be associated with febrile seizures (25% of cases)
See Figure 51.1 in color insert
Erythema Infectiosum (Fifth Disease)
Caused by parvovirus B19
Common in spring months and school-age children
Incubation period 6-14 days
Rash starts on the cheek giving a “slapped cheek” appearance
Maculopapular rash develops after 24 hours over trunk and extremities
Rash clears with a lacy pattern
Complications: transient arthritis, aplastic anemia in children with high bone marrow turnover (sickle cell disease, thalassemia, G6PD deficiency, spherocytosis)
Pregnancy risk:
50% of women are seropositive before pregnancy
Likelihood of transmission if exposed: 30-50%
2-10% rate of fetal loss
Measles (Rubeola)
Caused by measles virus (paramyxovirus)
Highly contagious (transmitted by nasal and oral droplets)
Incubation period: 1-2 weeks
Contagious 3 days before until 4 days after appearance of rash
Prodrome: cough, coryza, conjunctivitis, fever, photophobia
Clinical presentation:
Koplik spots (white papules on buccal mucosa) present 2 days before until 2 days after rash appears
Morbilliform rash appears behind the ears spreading toward face, trunk, and then extremities
Rash fades after 3-7 days; fine desquamation is common with the exception of palms and soles
Complications: otitis media, pneumonia, encephalitis, subacute sclerosing panencephalitis
See Figure 51.2 in color insert
Rubella
Generalized maculopapular rash with cervical, postauricular, and occipital lymphadenopathy
3-5 days of viral prodrome followed by a pink rash that spreads caudally from head to toes in 24 hours
Palatal petechiae may be present
Arthritis 1-2 weeks after the eruption (girls more commonly affected)
See Figure 51.3 in color insert
Scarlet Fever
Exotoxin-mediated rash secondary to group A β hemolytic Streptococcus infection of the pharynx, skin, or perianal area
Generalized pinpoint papular eruption (sandpaper rash)
Prominent in skin folds: Pastia’s lines
Strawberry tongue with circumoral pallor
Resolves with desquamation
Treatment: oral penicillin
See Figure 51.4 in color insert
Rocky Mountain Spotted Fever
Caused by Rickettsia rickettsii
Incubation period: 2-10 days
Clinical features:
Fever, headache, myalgias
Maculopapular rash erupts on day 3 of illness, may progress to hemorrhagic rash within 24-48 hours
Treatment: doxycycline or chloramphenicol
Vesicullobullous Eruptions
Chickenpox
Caused by varicella zoster virus
Incubation period: 2-3 weeks
Dual transmission: direct contact and airborne
Clinical features:
Crops of lesions every 3-5 days
Starts with papules → vesicles → pustules that resolve with crusting
Complications: secondary skin infection (particularly invasive GAS), necrotizing fasciitis, pneumonia, encephalitis
Treatment: supportiveRelated posts:
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