RT Book, Section A1 Shah, Ashish A1 Sobolewski, Brad A1 Mittiga, Matthew R. A2 Knoop, Kevin J. A2 Stack, Lawrence B. A2 Storrow, Alan B. A2 Thurman, R. Jason SR Print(0) ID 1181044322 T1 Erythema Infectiosum (Fifth Disease) (Rashes and Lesions) T2 The Atlas of Emergency Medicine, 5e YR 2021 FD 2021 PB McGraw-Hill PP New York, NY SN 9781260134940 LK accessemergencymedicine.mhmedical.com/content.aspx?aid=1181044322 RD 2024/03/28 AB Erythema infectiosum is a viral infection caused by parvovirus B19, presenting most commonly between 4 and 10 years of age. It begins with nonspecific prodromal symptoms including malaise, coryza, headache, fever, nausea, and diarrhea. In 25% of cases, the classic rash appears 2 to 5 days into the illness and is characterized initially by the “slapped cheeks” appearance of a bright red malar, macular rash that spares the nasal ridge and perioral areas. A reticulated, lacy erythematous maculopapular eruption with central clearing then appears on the extensor surfaces of extremities. The differential diagnosis includes other morbilliform eruptions such as measles, rubella, roseola, and infectious mononucleosis. Bacterial infections (eg, scarlet fever), drug reactions, and other skin conditions such as guttate psoriasis, papular urticaria, atopic dermatitis, and erythema multiforme are also included in the differential.