Atlas of Eyelid Lesions
INTRODUCTION An abscess is a collection of pus within a cavity formed in soft tissue or bone. It is usually associated with an infection caused by bacteria or parasites that gain access via a break in the skin or sometimes through hematogenous spread. Sometimes a sterile abscess can be induced by retained foreign material. Local tissue cells are destroyed by bacterial action or toxins and this triggers an inflammatory response by attracting large numbers of white blood cells. Regional blood flow is increased causing erythema, and vascular permeability is increased under the influence of released cytokines resulting in tissue edema. Patients with systemic diseases such as diabetes, or who are immunocompromized are at greater risk for developing an abscess from relatively trivial trauma or from a surgical wound. Eyelid abscess can be associated with paranasal and sinus infections or with diseases such as tuberculosis. Obstruction of skin glands or lacrimal ducts can become infected leading to abscess formation.