urticaria of the newborn
Papular mastocytosis/erythema toxicum/urticaria pigmentosa
This is believed to be an eruption due to a focal aggregation of mast cells in the dermis.
This condition occurs in infancy - usually in the first two days to two weeks of life. Lesions may be present at birth.
The condition is characterised by small brown-red macules or papules, which itch, redden and urticate after gentle rubbing (Darier's sign). The sites affected are the face, limbs and trunk. The palms and sole are spared.
Spontaneous improvement usually occurs throughout infancy and childhood. No treatment is required.
It is important to differentiate toxic erythema from septic pustules, especially those due to Staphylococcus aureus.
Last reviewed 01/2018