Basic science and pathophysiology
1) Erythema Toxicum Neonatorum
This is a common skin condition that affects 40-70% of all neonates2.
20% of cases present at birth however, most develop 24 to 48 hours later3.
Histologically the condition is characterised by collections of eosinophils just beneath the stratum corneum. However, the aetiology remains unknown3.
2) Transient Pustular Melanosis
This condition is not as common as Erythema Toxicum occurring in 1% of all Caucasian newborns5.
The condition is five times more prevalent in the Afro-Caribbean population
3) Milia
A very common condition that occurs in 50% of newborns7.
Histologically the condition is characterised by retention of keratin within the dermis.
4) Harlequin colour change
A condition that occurs in 10% of newborns8. However, it is often un-recognised.
The condition is thought to be related to hypothalamic immaturity resulting in dilatation of the peripheral vasculature.
5) Seborrhoeic Dermatitis
Occurs in infants between the second week of life and 6 months.
The exact cause is unknown however, there is evidence of involvement of the yeast Pityrosporum Ovale10.
6) Mongolian Blue Spot
Bilirubin metabolism
Unconjugated bilirubin (indirect bilirubin) is created from red blood cell breakdown and transported in the bloodstream mostly bound to albumin.
Unconjugated bilirubin is transported into the hepatocytes and conjugated with glucuronic acid.
Conjugated bilirubin (direct bilirubin) is excreted into the biliary system and, ultimately, the small intestine.
Most bilirubin is excreted into the stool but a small proportion is reabsorbed as part of the entero-hepatic circulation via the portal vein.
Neonates are more prone to jaundice as:
1) They have a relative polycythaemia and thus, increased red cell breakdown.
2) The liver is relatively immature and thus, unable to cope with normal bilirubin metabolism.
3) Changes in intestinal flora alter the entero-hepatic circulation.
In most babies jaundice is self-limiting and harmless.
This is termed physiological jaundice.
Physiological jaundice is very common with 60% of term and 80% of preterm (<37 weeks) infants developing jaundice in the first few weeks of life13
Bilirubin metabolism
Unconjugated bilirubin (indirect bilirubin) is created from red blood cell breakdown and transported in the bloodstream mostly bound to albumin.
Unconjugated bilirubin is transported into the hepatocytes and conjugated with glucuronic acid.
Conjugated bilirubin (direct bilirubin) is excreted into the biliary system and, ultimately, the small intestine.
Most bilirubin is excreted into the stool but a small proportion is reabsorbed as part of the entero-hepatic circulation via the portal vein.
Neonates are more prone to jaundice as:
1) They have a relative polycythaemia and thus, increased red cell breakdown.
2) The liver is relatively immature and thus, unable to cope with normal bilirubin metabolism.
3) Changes in intestinal flora alter the entero-hepatic circulation.