1.7 Pustula (Pustule)

Pustule

Superficial intraepidermal collection of cloudy or pus-laden fluid in the epidermis, follicular or acrosyringal opening
Color: yellow
Size: < 5 mm

May appear anywhere on body, often associated with hair follicle
Disseminated involvement of hair follicles = folliculitis
Disseminated involvement of acrosyringia

May develop crusts or erosions
Associated with vesicles and bullae

Sterile pustule (neutrophilic collections in pustular psoriasis), purulent contents (staphylococcal folliculitis)

Bacterial folliculitis, secondarily infected herpes simplex.
Pustular psoriasis
Acute generalized exanthematous pustulosis (drug reaction)
Acne vulgaris
Miliaria rubra pustulosa

Loss of adhesion of epidermal keratinocytes caused by infectious agents (herpes simplex virus, Staphylococcus aureus) inflammation or autoimmune mediated reactions