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: supportive
Stay updated, free articles. Join our Telegram channel

Full access? Get Clinical Tree

