Abscess

Abscess (from the Latin abscessus — “boil”) is a localized, encapsulated collection of pus resulting from purulent inflammation of tissues. An abscess is lined by a pyogenic membrane, which isolates the lesion from healthy tissues and prevents the spread of infection.

It is one of the forms of localized purulent inflammation in which the body creates a barrier around the infectious focus. This protective capsule (lined by the pyogenic membrane) consists of granulation and fibrous tissues. While confining the process, it also produces purulent exudate.

Etiology and pathophysiology

Abscesses are primarily caused by pathogenic bacteria penetrating into tissues, most commonly Staphylococcus aureus. In response to invasion, an inflammatory reaction develops with a massive influx of neutrophils. Enzymes released by neutrophils and bacteria cause tissue lysis (liquefaction), forming a cavity filled with pus.

Clinical significance

Abscesses presents with local signs of inflammation, such as pain, swelling, erythema, and localized elevation in temperature. Upon maturation, the key diagnostic sign is fluctuation (a wave-like sensation on palpation indicating fluid within a cavity). Deep abscesses are diagnosed using ultrasound (US) or computed tomography (CT).

Surgery is the primary treatment method: the purulent cavity is incised, drained, and irrigated (“Ubi pus, ibi evacua” — “Where there is pus, evacuate it”). Antibiotic therapy plays a supportive role. Timely treatment ensures a favorable prognosis; otherwise, there is a high risk of rupture, phlegmon, or sepsis.

Differential Diagnosis

An abscess must be distinguished from phlegmon, which is a diffuse purulent inflammation without clear boundaries or capsule. It should also be differentiated from empyema, which is the accumulation of pus within a pre-existing anatomical cavity (e.g., the pleural cavity).