A cutaneous abscess is a localized cavity of purulent material in the superficial skin and soft tissue. It causes a fluctuant swelling or mass, with inflammatory changes in the surrounding soft tissue. The abscess may progress to a spontaneous discharge of its contents through its external or internal surface (1,2,3).

The preferred treatment for the cutaneous abscess is surgical incision and drainage (1,2,3,4,5). Percutaneous needle aspiration alone inadequately drains an abscess cavity and often results in persistent or recurrent abscess formation. Incision and drainage of an abscess likely mitigates potential bacteremic dissemination or extension into important adjacent tissues (e.g., vascular structures). The procedure is simple, may be done quickly, and is usually curative for all age groups. It is commonly performed by physician and physician extenders in the emergency or outpatient setting.

Evaluation and treatment of superficial abscesses accounts for 1% to 2% of all emergency and outpatient visits (1,2,3,4,5). Although cutaneous abscesses are among the most common soft-tissue infections, only a few controlled studies of their treatment in adults and children have been carried out.

A cutaneous abscess occurs after disruption of the normal barriers of the skin that prevent natural bacterial colonization from becoming an infection. Localized cellulitis first develops when bacteria proliferate within the skin and subcutaneous tissues. As bacterial enzymatic activity produces necrosis, liquefaction, and a leukocytic response, pus forms and an abscess results. Cellulitis generally resolves with antibiotic therapy, whereas an abscess usually does not respond to antibiotics alone without open drainage of the pus.

Common causes for the disruption of the normal skin barriers to infection include direct trauma to or a foreign body in the skin or soft tissues; injection or accumulation of bacterial inoculum (e.g., injury from cat bite or rusty nail); decreased or inadequate blood or lymphatic circulation (e.g., necrosis, hemorrhage); and poor host systemic immunity (e.g., debilitating disease, immunocompromised host). Proliferation of bacteria subsequently occurs and may progress to an abscess. Often a keratin plug will sufficiently obstruct the normal outflow of a secretory gland to prevent the normal clearance of bacterial colonization. Areas prone to such obstruction are the axilla, groin, perineum, and breast (4). In the infant or younger child, common sites also include the perianal area from mucocutaneous infection or enterocutaneous fistula (3) and the digits from finger sucking or biting (6).

Overall, Staphylococcus aureus is the predominant organism isolated from most abscesses, especially as a single isolate. In many communities, methicillin-resistant S. aureus(MRSA) is an established organism that accounts for as many as half of the S. Aureus isolates in soft-tissue infections (7). The causative organism usually reflects the indigenous flora of the specific site. Oral flora are found in abscesses that result from prolonged or repeated contact with the mouth, as in the fingers or toes of infants (see Chapters 115 and 116). Mixed aerobic and anaerobic flora predominates in the abscesses of the head and fingers in children because they are typically associated with oral or perianal flora. The organisms commonly isolated include Escherichia coli and anaerobic organisms, such as Peptostreptococcus, Bacteroides, Fusobacterium, and Clostridium species (4,5,6,7). Fecal flora is usually isolated from abscesses of the anogenital, vulvovaginal, inguinal, and perirectal areas. These bacteria are most commonly mixed aerobic and anaerobic organisms: E. coli,
group D streptococci, Neisseria gonorrhoeae, or Peptostreptococcus, Enterobacter, or Bacteroides species. Abscesses of the axilla are commonly caused by Gram-negative aerobic organisms, E. coli or Enterobacter species. Aerobic organisms indigenous to the skin and secretory gland typically cause abscesses distant from the oral or anogenital areas in the general population; they include S. aureus, coagulase-negative staphylococci, and α– and β-hemolytic streptococci (4,5,6,7).

Clinically, both cellulitis and an abscess may appear as a localized area of pain (dolor), erythema (rubor), warmth (calor), edema (tumor), or induration; the patient usually complains of localized pain and swelling without fever. Fluctuance on physical examination with or without spontaneous drainage usually indicates the presence of an abscess (2,5). A definitive diagnosis of an abscess can be made based on successful percutaneous needle (18-gauge) aspiration of pus from the site (2).

The treatment for a cutaneous abscess is surgical incision and drainage (1,2,3,4). Optimal management of cutaneous abscesses in the emergency or outpatient setting requires the following appropriate conditions: (a) the inflammatory mass is an acute, superficial, and localized cutaneous abscess without extension to deeper structures; (b) the child will be adequately cooperative when the procedure is performed under local or regional anesthesia; and (c) the child has no other apparent medical condition that precludes outpatient management, such as airway or anatomical anomalies. If these conditions are not met, or if the depth, extent, or cosmetic implications of the abscess are questionable, a pediatric surgical consultation and treatment under general anesthesia may be more appropriate.