Subcutaneous abscesses are commonly seen in the Emergency Department. Approximately 3% of patients present with this chief complaint.1,2 Abscesses occur in numerous anatomic areas with varied etiology and bacteriology. An abscess is a tender and fluctuant mass located in the dermal or subdermal tissue. It usually demonstrates the classic inflammatory responses of rubor, tumor, dolor, and calor. The abscess is usually tender. The surrounding and underlying tissue should not be tender.3-5
Incision and drainage is the definitive treatment of a simple soft tissue abscess.5-7 This procedure results in significant improvement in symptoms and a rapid resolution of the infection in uncomplicated cases.8 The addition of antimicrobial therapy is needed for systemic signs of sepsis, immunocompromised patients, if source control is incomplete, and for abscesses with significant cellulitis.5 Premature incision before localization of pus will not be curative and may be deleterious. Oral antibiotics and warm compresses may be of value in helping the infection to coalesce in cases of immature abscesses or cellulitis. These methods are not a substitute for incision and drainage and should not be continued for more than 24 to 36 hours without a reassessment of the patient. The role for ancillary antibiotic use has come into question with the emergence of methicillin-resistant Staphylococcus aureus (MRSA).
ANATOMY AND PATHOPHYSIOLOGY
An abscess is a localized collection of pus caused by suppuration buried in a tissue, organ, or confined space.9 Intact skin is very resistant to bacterial invasion. Localized pyogenic infections are usually initiated by a breakdown in the normal epithelial defense mechanisms in the normal host. Plugging of the ducts of a superficial exocrine gland may initiate the process. Occlusion prevents desquamation and provides a moist environment for organisms to proliferate. The combination of a high concentration of organisms, the presence of nutrients, and sufficient damage to the corneal skin layer to allow organisms to penetrate the skin defenses results in abscess formation.10,11
Subcutaneous abscesses typically begin as a cellulitis with organisms that cause necrosis, liquefaction, and accumulation of leukocytes and debris. Early stages appear as an area of hyperemia and tender inflammation that later becomes fluctuant as an exudate of leukocytes, necrotic material, and cellular debris accumulates. This is followed by loculation and walling off of the pus. This progresses and the area of liquefaction increases until it “points” and eventually ruptures through the area of least resistance.4 A simple abscess should not extend into deeper tissues or have multiloculated extension. The induration and erythema are limited to a defined area of the abscess. An abscess with extensive overlying cellulitis, multiloculated extensions, or systemic signs of illness can be considered complex in comparison to a simple abscess.5
The body area involved depends upon host factors (e.g., drug use, employment-related exposures, or minor ...