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, 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. These molecules cause redness and swelling in the skin and attract immune cells.Eosinophils 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 activate the immune system when they enter hair follicles for the first time.
Becaplermin (brand name Regranex) is a cicatrizant, available as a topical gel. Regranex is a human platelet-derived growth factor indicated along with good wound care for the treatment of lower extremity diabetic neuropathic ulcers. It is also known as "platelet-derived growth factor BB". Medical uses
The drug is used for the treatment of diabetic foot ulcers. Studies of becaplermin showed that when used with good wound care, complete healing significantly increased and the ulcers healed on average 6 weeks faster. Pharmacoeconomic studies reinforce the cost effectiveness of becaplermin as an adjunct to good wound care.The amount of becaplermin to be applied will vary depending upon the size of the ulcer area. Becaplermin should be stored in the refrigerator. Analysis of healing human wounds showed that PDGF-BB induces fibroblast proliferation and differentiation and was found to increase healing in patients with decreased healing capacity, such as people living with diabetes. Contraindications
Becaplermin must not be used at the site of a skin cancer. Adverse effects
The most common side effects in clinical studies were erythematous rashes.A boxed warning has been added to the safety label to describe an increase rate of death from cancer when three or more tubes are used. Regranex should be used with caution in patients with known malignancy. See also
Nepidermin

References
External links
Regranex website