Miliaria

Miliaria is a relatively common vesicular eruption seen in the first few weeks of life and can occur in all newborns given the right conditions.

Miliaria is the result of keratin plugging of the relatively immature neonatal eccrine sweat ducts with resultant trapping of sweat in the skin.
When the trapped sweat triggers a localized inflammatory response, miliaria rubra is seen.
Common triggers include excessive swaddling, heat, fever, and occlusive dressings.

Miliaria crystallina presents as pinpoint, 1 to 2 mm, clear to white superficial vesicles (Fig. 2.12).
Miliaria rubra (also called “prickly heat”) presents as grouped, small pink to red papules, vesicles or papulovesicles with a surrounding rim of erythema (Fig. 2.13).
Miliaria rubra is most commonly seen in occluded areas of the body such as the body folds and the back.
Palms and soles are never involved.

Diagnosis is based on clinical recognition.
A KOH preparation, Gram stain, and/or Tzanck smear can be helpful to rule out infectious causes of vesicles and pustules.

Differential Diagnosis

Congenital or Infantile Candidiasis

Tiny pustules or collarettes of scale on an erythematous base.
When present at birth is usually widespread and often present on palms and soles.
KOH of pustule contents will reveal pseudohyphae and budding yeast.

Neonatal Herpes Infection

Grouped vesicles on an erythematous base.
There is usually a history of maternal HSV infection and Tzanck smear will show multinucleated giant cells.

Erythema Toxicum Neonatorum (see above)

Common eruption papules or pustules on erythematous wheal usually in haphazard distribution.
Resolves completely within 2 weeks.

Folliculitis

Management

After an infectious etiology has been ruled out, parents can be reassured that this is a benign eruption.
Spontaneous resolution with cooling usually occurs.
Counsel on avoidance excessive heat, humidity, and swaddling.
Avoid excessive use of thick (ointment based) emollients in hot, humid climates or in cold climates especially when bundling baby.
Use of loose fitting cotton clothing, cooler baths, and air conditioning can be helpful in the prevention of outbreaks.

Helpful Hint

Perform a KOH, Gram stain, or Tzanck smear to rule out more serious causes of vesicles or pustules on a newborn's skin.