Furuncle

Causes and mechanism of development

Purulent inflammation is triggered by various microtraumas of the skin, including scratching in pruritic dermatoses. A key role is played by the weakening of the body's defense mechanisms. Predisposing factors include hypovitaminosis, concomitant skin diseases, and metabolic disorders (most commonly diabetes mellitus).

The pathogenesis of the disease includes several successive stages:

1. Formation of the primary purulent pustule.
2. Penetration of the microflora from the hair follicle deeper into the papillary dermis.
3. Formation of a dense inflammatory infiltrate.
4. Appearance of a necrosis focus in the center—the so-called necrotic core.
5. Accumulation of purulent masses around the dead tissues.
6. Rejection of the necrotic core along with pus.
7. Filling of the resulting defect with granulation tissue followed by scarring.

Clinical manifestations

The disease manifests with the appearance of a small pustule or painful induration within the skin thickness. Typical locations: back of the neck, forearms, dorsal hand, face, and thighs. As it progresses, symptoms of general intoxication join: malaise and fever. The severity of the pain syndrome depends on the location: pain is most intense where the skin is tightly fused with underlying tissues (occiput, scalp, external auditory canal, dorsal surface of the fingers).

Upon examination (Status localis), four stages are distinguished:

• Initial stage: a pustule with a zone of hyperemia around it (less commonly, simply a hyperemic induration).
• Stage of infiltration: a cone-shaped purple-red infiltrate with indistinct borders, 0.5–1.5 cm in diameter, is formed.
• Stage of abscess formation: a softening area or pus beneath a crust appears in the center. When discharge escapes, greenish tissue is visualized—the tip of the core.
• Stage of resolution: after rejection of the core with pus and blood, a crater-like pit is formed, which heals within 2–3 days with the formation of a retracted scar.

Outcomes and severe complications

In unfavorable cases or impaired pus outflow, the development of an abscessing furuncle is possible. In this case, the necrotic core completely melts, a spherical swelling with the symptom of fluctuation forms, which requires surgical intervention.

The infection can spread via lymphatic pathways, causing lymphangitis (red streaks from the focus) and lymphadenitis (enlargement of regional lymph nodes). In such situations, antibiotic therapy is mandatory.

A malignant course of a facial furuncle (upper lip, eyelids, superciliary arches) is extremely dangerous. The infection can spread retrogradely via facial veins into the ophthalmic vein, and from there into the cavernous sinus. This leads to purulent thrombophlebitis and life-threatening purulent meningitis. With generalization of the infection, sepsis develops (intermittent fever, shaking chills, delirium, pallor) with the formation of metastatic abscesses in internal organs (septicopyemia).

Principles of treatment

The management tactic for an uncomplicated furuncle is conservative. It is strictly forbidden to squeeze the pustule, shave it off with a blade, or apply warming compresses.

At the infiltration stage, the surrounding skin is treated with a 70% ethanol solution or 2% salicylic alcohol, and UHF therapy is applied. After opening the pustule, dressings with proteolytic enzymes or hypertonic sodium chloride solution are used, and UV irradiation is prescribed. Once the core has separated, ointment dressings are applied to the wound (chloramphenicol emulsion, dioxomethyltetrahydropyrimidine ointment).

Special attention is paid to facial furuncles. The patient requires urgent hospitalization in a surgical department, strict bed rest, and systemic antibiotic therapy. Food should be pureed to limit chewing movements. In recurrent courses (furunculosis), screening for diabetes mellitus and hypovitaminosis is performed, as well as immunization with staphylococcal toxoid.

Class and exam questions

What else to study on this topic

• Pathogenesis and stages of necrotic core formation
• Differences in treatment tactics for an abscessing furuncle
• Mechanism of development of purulent meningitis when the focus is localized on the face
• Differential diagnosis of a furuncle with other pyogenic skin diseases
• Principles of immunization with staphylococcal toxoid in furunculosis

Other topics from the section "CHAPTER 11. SURGICAL INFECTION (PURULENT-INFLAMMATORY DISEASES)"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.