Tierdermatologie Deisenhofen Consultations
Papules may be present with or without pustules. Papules represent a
collection of inflammatory cells within the dermis and it is these cells which
result in the dermal swelling.
Some will be centred on a hair follicle => perifolliculitis is likely, so one must
consider the follicular infections demodicosis, dermatophytosis and bacterial
Some papules will have the surface "excoriated" or - especially in the case of
a spongiotic allergic reaction - will have formed a small vesicle on the top
which rapidly ruptures. These are called crusted papules.
An interfollicular papule is frequently associated with insect bites (mosquito
bite/ culicoides bite/ flea bite hypersensitivity).
Pustules are accumulations of cells and frequently serum within an
intraepidermal space. Neutrophils and / or eosinophils give pustules their
opaque colour. They are most frequently associated with infections and care
should be taken (as in papules) to determine whether the pustule is centred
on a hair follicle.
In the rare case of pemphigus foliaceus, the pustules may be large and
contain numbers of - and groups of - acantholytic cells. It is important to
remember that acantholytic cells may also be obtained from pyoderma
pustules, a diagnosis of pemphigus foliaceus requires a skin biopsy!
Care should be taken when sampling a pustule for cytology. So that the cells
in the underlying dermis are not also collected, hold the needle tip parallel to
the surface of the skin.
A follicular pustule