Skin Disorders Guide

Diagnostic Hallmarks

1. Distribution: no characteristic pattern
2. Sudden onset
3. Pain and tenderness
4. Response to therapy

Clinical Presentation

Furuncles are painful, dome-shaped or slope-shouldered, bright red nodules 1.5 to 3 cm in diameter. Usually, only a single furuncle is present; multiple lesions, if closely grouped, may coalesce to form a carbuncle. The classic signs of inflammation (rubor, dolor, color, and tumor) are all present. The development of a furuncle is an acute event. From the point of onset to full development requires only 24 to 48 hours. Early lesions are firm on palpation, but older lesions may develop a fluctuant central area. Lesions that become fluctuant may “point” with a small pustule. Regional lymphadenopathy is occasionally present, but malaise and fever are not regularly found. Furunculosis should be differentiated from hidradenitis suppurativa and inflamed epidermoid cysts .

Course and Prognosis

Furuncles left untreated resolve spontaneously in 10 to 20 days. During this time, fluctuant lesions may rupture and drain. The pus from such lesions often causes bacterial contamination of adjacent skin, leading to the development of multiple new lesions. In debilitated or immunocompromised patients, furunculosis sometimes progresses to more serious, systemic staphylococcal infection.

Pathogenesis

Furunculosis is a bacterial infection caused by coagulase-positive Staphylococcus aureus. The infection develops around the hair follicle and is similar to, but much deeper than, that found in folliculitis. Events favoring the development of furunculosis include tissue trauma and the presence of heat and moisture. Persons with recurrent furunculosis are often chronic carriers of staphylococcal bacteria in the nose and throat. Diabetes mellitus is said to be more common in patients with recurrent furunculosis, but such a relationship, if it exists, does not warrant routine glucose determinations.

Therapy

Patients with furunculosis should be treated with systemically administered antibiotics. The use of phenoxymethy lpenicillin may be sufficient, but generally those penicillins, such as dicloxacillin, that are resistant to penicillinase degradation are preferred. Erythromycin and related new antibiotics are also appropriate; they represent the antibiotics of choice for those patients allergic to penicillin.

Traditionally, warm soaks have been used as adjunctive therapy, but there are no good data demonstrating their usefulness. Incision and drainage are appropriate only where lesions are present. The placement of drains or gauze packing following incision and drainage is rarely necessary.