2025 – PAGE 161 – DERMATOLOGY

(DOUBLE TAKE) ERYTHEMA MARGINATUM

• • Erythema marginatum is a transient, erythematous, macular and light colored. It is described as being “SERPENTiginous” (snakelike) and the MARGINs are noted progress as the center clears. It is part of the Jones criteria for Rheumatic Fever.
  • IMAGE: www.pbrlinks.com/ERYTHEMA1

MNEMONIC: The E in Erythema is part of the E in jonEs, and the name MARGINatum should remind you to look for an interesting description of the rash’s MARGINs. Erythema MARGINatum.

 (DOUBLE TAKE) ERYTHEMA INFECTIOUSUM

Erythema infectiosum IS an INFECTIOUS rash!!! It is caused by Parvovirus B19. It is also called Fifth Disease Look for erythematous facial flushing of the cheeks (sometimes described as “slapped cheeks” appearance). The extremities will have diffuse macular (or morbilliform) erythema (especially on the extensor surfaces) referred to as “lacy” or “reticular.” Diagnose with IgM titers. (There is no culture or rapid antigen available.)

PEARLS: The rash occurs AFTER the slapped cheeks rash (often a week later). Patients may also have knee or ankle pain. Parvovirus B19 infection can result in APLASTIC CRISIS. Intrauterine exposure can result in hydrops fetalis.

MNEMONIC: infectio5uM = FIFTH disease = “Five fingers.” Imagine a cheek being SLAPPED with FIVE fingers covered by a white LACY glove with a red M on the back of it (extensor surface). M = IgM titers.

MNEMONIC: ParVoVirus B19: From now on, say/think “parVoVirus V19.” V = Roman numeral 5!

ERYTHEMA TOXICUM NEONATORUM

See in next section (Newborn Rashes).