User:FutureMD-SR/Erythema toxicum neonatorum

Erythema toxicum neonatorum is a common, non-threatening rash in newborns. It appears in 30-70% of newborns within the first week of life, and it typically improves within 1-2 weeks. It does not occur outside of the newborn period, but presentation may be slightly delayed in premature babies.

The appearance of erythema toxicum neonatorum is variable. It typically includes blotchy red spots, often with overlying firm, yellow-white papules and pustules. There may be only a few or many lesions. The lesions can appear almost anywhere on the body, and individual lesions may appear and disappear within hours. There are no other symptoms associated with erythema toxicum neonatorum, and the rash does not have any long-term effects on the skin. Erythema toxicum neonatorum is not harmful and does not require any treatment.

Presentation
Erythema toxicum neonatorum typically appears on the second or third day of life,

The rash has a variable appearance, ranging from minimal blotchy red spots to numerous yellow-white papules and pustules. The classic presentation is 1-3 mm, firm, yellow-white papules with a surrounding red halo, and the rash is often described as "flea-bitten" for this reason. Papules may resolve or change into pustules over time. Lesions may be sparse or numerous, and they may be clustered or widespread. The rash often appears on the cheeks and may later spread throughout the face, trunk, arms, and legs. The hands and feet are not affected.

Individual lesions may wax and wane over hours or days.

Cause
Erythema toxicum neonatorum is associated with activation of the immune system, but its exact cause is unknown. Multiple inflammatory factors have been detected in erythema toxicum neonatorum lesions, including IL-1alpha, IL-1beta, IL-8, and eotaxin.

Eosinophils and other inflammatory cells are found in the upper layer of the skin in erythema toxicum neonatorum lesions. Inflammatory cells tend to cluster around hair follicles in particular. The leading hypothesis about the cause of erythema toxicum neonatorum is that the immune system is activated by the introduction of bacteria into hair follicles. This is part of a normal process that occurs in newborns in which bacteria from the environment start to colonize the newborn's skin. It is unclear whether the immune response seen in erythema toxicum neonatorum provides any benefit to the newborn.

Diagnosis
Erythema toxicum neonatorum is typically diagnosed following an exam by a health professional, with no additional testing needed. If further confirmation of the diagnosis is necessary, the contents of a pustule can be examined under a microscope. Wright stain will reveal eosinophils and other inflammatory cells. Since the rash in erythema toxicum neonatorum can vary in appearance, it may be confused with other causes of rash in newborns. Certain infections can cause pustules or vesicles, which may be similar in appearance to the pustules seen in erythema toxicum neonatorum. Bacterial infections, including Staphylococcus and Streptococcus infections, will typically cause additional symptoms consistent with sepsis. If bacteria are present, they can be diagnosed following Gram stain and culture of pustular contents. Fungal infection with Candida typically causes additional symptoms, including thrush, and pseudohyphae can be seen microscopically. Viral infections, including infection with herpes simplex virus and varicella zoster virus, often present with vesicles on a reddish base. These viruses can be diagnosed by Tzanck test, which will reveal multinucleated giant cells.

Treatment
Erythema toxicum neonatorum resolves without treatment, typically within one or two weeks. There are no associated systemic symptoms or long-term consequences of the rash. Parents are frequently concerned by the rapidly changing rash, but should be reassured that it is not harmful and will improve on its own. (not sure if I should include or not)

Epidemiology
The exact prevalence of erythema toxicum neonatorum is unknown, and studies estimate prevalence as low as 3.7 percent to as high as 72 percent. It is one of the most commonly diagnosed rashes in healthy babies. It is more common among infants born at higher gestational age and is rare among premature infants. Erythema toxicum neonatorum is more likely to develop in infants delivered vaginally. Higher birth weight is an additional risk factor. There may be a slightly increased risk in males, but this association is unclear. There are no known associations with race or ethnicity.

History
The rash of erythema toxicum neonatorum has been described by physicians for centuries. Ancient Mesopotamians believed that it represented a cleansing mechanism against the mother's blood. Later physicians believed that it was caused by the skin's response to meconium. The name erythema toxicum neonatorum was first used by Dr. Karl Leiner in 1912 because he believed that the rash was caused by enterotoxins. Although Leiner's hypothesis was incorrect and the rash is not actually caused by toxins, the name erythema toxicum neonatorum continues to be used.