(aye aye) Infective( viral, bacterial, fungal) or Inflammatory eg psoriasis or a pustular drug reaction. Common causes include Staph folliculitis , modified fungal infection or if the vesicles are grouped herpes simplex. Pustules on the face are Acne, Rosacea, Staph folliculitis or H Simplex if grouped.
When we see pustules we have a tendency to think infection and often limit ourselves to only bacterial infections at that. Remember pustules can occur with fungal and viral infections as well and never forget that some pustules are not due to infection but to infiltration of the skin by neutrophils in Inflammatory skin diseases such as psoriasis and drug eruptions. There are also a few other very rare inflammatory disorders such as acrodermatitis enteropathica (zinc deficiency) and the glucagonoma syndrome from underlying pancreatic malignancy that can have pustules at the advancing edge of the lesion and thereby simulate a fungal infection.
The images below include variants of pustular psoriasis, both localised and generalised and infected pompholyx eczema.
