Photo Rounds Friday Archive

Erythematous malar rash

Post Date: 09/11/2009

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A 2-year-old boy came in with mild, flu-like symptoms and a rash. He had an erythematous malar rash and a temperature of 100.1º F. No one else in the family was ill, but he did attend day care. Besides the rash and fever, the remainder of his physical exam was normal.

What's your diagnosis?

The "slapped cheek" appearance made the diagnosis easy for erythema infectiosum. Erythema infectiosum is also commonly referred to as "fifth disease" since it represents the fifth of the 6 common childhood viral exanthems. We reassured the parents that the rash would go away on its own.

The following day, the mother brought her son in again because he developed a new rash: a "lace-like" erythematous rash on his trunk and extremities. We reassured her that this was part of the same viral exanthem.

Erythema infectiosum is caused by parvovirus B19 and is self-limited. In rare cases, an infection in pregnancy can lead to fetal death. Pregnant women who are exposed to, or have symptoms of, parvovirus infection should have serologic testing.

Prior to 20 weeks gestation, women testing positive for acute infection (ie, positive immunoglobulin M and negative immunoglobulin G) should be counseled concerning the low risk of fetal loss and congenital anomalies. If positive, some experts recommend that the patient receive ultrasounds to look for signs of fetal hydrops. Intrauterine transfusion is currently the only effective treatment to alleviate fetal anemia.

Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Mayeaux EJ. Fifth disease. In: Usatine R, Smith M, Mayeaux EJ, Chumley H, Tysinger J, eds. The Color Atlas of Family Medicine. New York, NY: McGraw-Hill; 2009:507-509.

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