Types

Childhood exanthems vary greatly depending on factors such as location, size, elevation, palpability and the content of the associated skin eruptions.

Seven broad types have been identified:

Macule

A macule is a circumscribed area of change in normal skin colour, with no skin elevation or depression. It may be any size.

Papule

A papule is a solid raised lesion up to 0.5 cm in greatest diameter.

Note, however, that some text definitions use 1.0 cm as a cut-off limit instead of 0.5 cm.

Nodule

A nodule is similar to a papule but is located deeper in the dermis or subcutaneous tissue.

Nodules are differentiated from papules by palpability and depth, rather than size.

Plaque

A plaque is an elevation of skin occupying a relatively large area in relation to its height.

It can often be formed by a confluence of papules.

Pustule

A pustule is a circumscribed elevation of skin containing purulent fluid of variable character.

The fluid may be white, yellow, greenish or haemorrhagic.

Vesicle

A vesicle is a circumscribed, elevated, fluid-containing lesion less than 0.5 cm in its greatest diameter. It may be intra-epidermal or sub-epidermal in origin.

Note, however, that some text definitions use 1.0 cm as a cut-off limit instead of 0.5 cm.

Bulla

A bulla is similar to a vesicle, except the lesion is more than 0.5 cm in its greatest diameter.

Note, however, that some text definitions use 1.0 cm as a cut-off limit to replace 0.5 cm.