Erythema toxicum neonatorum is a common, non-threatening
rash
A rash is a change of the human skin which affects its color, appearance, or texture.
A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, c ...
in
newborns
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used t ...
.
It appears in 4-70% of newborns within the first week of life, and it typically improves within 1–2 weeks.
It only occurs during the newborn period, but may appear slightly later in
premature
Premature may refer to:
* ''Premature'' (2014 film), an American comedy film
* ''Premature'' (2019 film), an American romantic drama film
* '' PREMature'', a 2015 British television drama miniseries
See also
* Premature aging, of an organism
* ...
babies.
The rash has a variable appearance. It typically includes
blotchy red spots, often with overlying firm, yellow-white
bumps
A bumps race is a form of rowing race in which a number of boats chase each other in single file, each crew attempting to catch and ‘bump’ the boat in front without being caught by the boat behind.
The form is mainly used in intercollegia ...
or pus-filled boils.
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.
Epidemiology
The exact
prevalence
In epidemiology, prevalence is the proportion of a particular population found to be affected by a medical condition (typically a disease or a risk factor such as smoking or seatbelt use) at a specific time. It is derived by comparing the number o ...
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
In obstetrics, gestational age is a measure of the age of a pregnancy which is taken from the beginning of the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method if available. Su ...
and is rare among premature infants. Erythema toxicum neonatorum is more likely to develop in infants
delivered vaginally.
Higher
birth weight
Birth weight is the body weight of a baby at its birth. The average birth weight in babies of European descent is , with the normative range between . On average, babies of South Asian and Chinese descent weigh about . As far as low birth weigh ...
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.
Presentation
Erythema toxicum neonatorum usually appears during the first week of life, most often on day two.
It may develop several days or weeks later in premature babies.
The rash has a variable appearance, ranging from a few blotchy red spots to many yellow-white bumps and boils. The classic presentation is 1–3 mm, firm, yellow-white bumps with a surrounding red halo. The rash is often described as "flea-bitten." There may be only a few or many lesions, and they may be clustered or widespread. The rash often appears on the cheeks first and may later spread throughout the face, trunk, arms, and legs.
Lesions most often appear on the thighs, buttocks, and trunk. The palms and soles are not affected, likely because the skin in these areas does not have
hair follicles.
Individual lesions may grow and shrink over hours or days. They usually fade within a week or two.
The rash may recur within the next few weeks, but this is rare.
Cause
Erythema toxicum neonatorum is related to activation of the
immune system
The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splint ...
, but its exact cause is unknown. Many
inflammatory factors have been detected in erythema toxicum neonatorum lesions, including
IL-1alpha,
IL-1beta,
IL-8, and
eotaxin
The eotaxins are a CC chemokine subfamily of eosinophil chemotactic proteins. Eotaxin is a special CC chemokine because it primarily attracts eosinophils. By being a chemoattractant for eosinophils, eotaxin has a direct relationship with inflammat ...
.
These molecules cause redness and swelling in the skin and attract immune cells.
Eosinophil
Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...
s and other immune cells are found in the
upper layer of the skin in erythema toxicum neonatorum lesions.
Immune cells tend to cluster around hair follicles in particular. The leading hypothesis about the cause of erythema toxicum neonatorum is that
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
activate the immune system when they enter hair follicles for the first time.
This is part of a normal process in which bacteria from the environment start to grow on a baby's
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different de ...
. It is unknown whether the immune response that causes erythema toxicum neonatorum is helpful to the baby.
Recent research indicates an association with ''
Demodex
''Demodex'' is a genus of tiny mites that live in or near hair follicles of mammals. Around 65 species of ''Demodex'' are known. Two species live on humans: '' Demodex folliculorum'' and '' Demodex brevis'', both frequently referred to as eyela ...
'' mites infestation (
demodicosis
Demodicosis , also called Demodex folliculitis in humans and demodectic mange () or red mange in animals, is caused by a sensitivity to and overpopulation of '' Demodex spp.'' as the host's immune system is unable to keep the mites under control. ...
).
Diagnosis
Health professionals can diagnose erythema toxicum neonatorum with a skin exam. Most cases of erythema toxicum neonatorum can be diagnosed without further testing. If more testing is needed to make a diagnosis, the contents of a lesion can be examined under a
microscope
A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisi ...
. A health professional may make a small cut into a pus-filled lesion and collect a swab of pus for testing. Lesions caused by erythema toxicum neonatorum contain eosinophils and other immune cells. These cells can be seen under a microscope when a special
stain is applied to the sample.
Since the appearance of erythema toxicum neonatorum varies, it may be confused with other newborn rashes. Some newborn infections cause bumps or boils, which may look like erythema toxicum neonatorum.
Bacterial infections, including
Staphylococcus and
Streptococcus
''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...
infections, almost always cause additional symptoms. These symptoms may be
severe, and they are usually not limited to rash. Bacterial rashes can be diagnosed by testing pus from a lesion along with a blood sample. Bacteria can be seen under a microscope with a special
stain or may be found on a
culture
Culture () is an umbrella term which encompasses the social behavior, institutions, and norms found in human societies, as well as the knowledge, beliefs, arts, laws, customs, capabilities, and habits of the individuals in these groups ...
. Fungal infection with
Candida may also cause a similar rash in newborns, but it usually causes additional symptoms like thrush. Similarly, fungus can be seen under a microscope or found on a culture. Some viral infections may cause a rash with boils on a reddish base. Rashes caused by
herpes simplex virus and
varicella zoster virus
Varicella-zoster virus (VZV), also known as human herpesvirus 3 (HHV-3, HHV3) or ''Human alphaherpesvirus 3'' (taxonomically), is one of nine known herpes viruses that can infect humans. It causes chickenpox (varicella) commonly affecting chil ...
in particular may be confused with erythema toxicum neonatorum. These viruses are diagnosed by
scraping the base of a lesion.
Multinucleated giant cells
A giant cell (also known as multinucleated giant cell, or multinucleate giant cell) is a mass formed by the union of several distinct cells (usually histiocytes), often forming a granuloma. Although there is typically a focus on the pathological ...
can be seen under a microscope. Some of these tests may be ordered if the diagnosis is unclear.
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.
History
The rash of erythema toxicum neonatorum has been described by doctors 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
enterotoxin
An enterotoxin is a protein exotoxin released by a microorganism that targets the intestines.
Enterotoxins are chromosomally encoded or plasmid encoded exotoxins that are produced and secreted from several bacterial organisms. They are heat la ...
s. Although Leiner's hypothesis was incorrect and the rash is not actually caused by toxins, the medical community continues to call the rash erythema toxicum neonatorum.
References
External links
{{Certain conditions originating in the perinatal period
Eosinophilic cutaneous conditions
Neonatology