Core Dermatology Diagnoses / CategoriesInfectious

Abscess, furuncle, carbuncle

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Publish date: Posted on
Last updated: November 11, 2023

Keywords #

Carbuncle
Furuncle
Abscess
Cellulitis
Folliculitis
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Diagnosis #

Furuncles and carbuncles are characterized by abscess formation centering around hair follicles. There are varying levels of severity and cases may either be self-limited or recurring. Most cases are caused by staphylococcal infection and are self-limited, but have better cure rates with treatment. Treatment consists of incision and drainage in simple cases, with additional antibiotic coverage in severe or recurring cases.[1,3]

Key Concepts #
  • Abscesses, furuncles, and carbuncles are very common skin infections.
  • They represent a progression in severity of a process usually caused by a Staphylococcus infection.[3]
  • Furuncles and carbuncles are characterized by folliculocentric dermal or subcutaneous abscess formation, and occur on hair-bearing skin.
  • Can usually be cured with incision and drainage alone.
  • May require antibiotic therapy in more severe or recurring cases.
  • If lesions continue to recur, an underlying cause should be investigated.[1]
Epidemiology #

Skin and soft-tissue infections are some of the most common human illnesses. Prevalence is estimated to be ~1,200 per 100,000 people and is relatively stable across geographical areas. They may happen at any age. Definitive risk factors for abscesses, furuncles, and carbuncles have not been established, but have been associated with immunosuppression, poor hygiene, obesity, injection drug use, and colonization with S. aureus, etc. Most cases can be cured with a simple incision and drainage, but more severe cases may require additional antibiotic coverage as well.[1,4]

Clinical Features #
  • Abscess: present initially as warm, tender, red nodules that can occur anywhere on the skin. Will usually enlarge without treatment and form a pus-filled cavity.[3]
  • Furuncle: firm, tender, erythematous nodules that occur on hair-bearing skin and involve hair follicles. They can be painful, have surrounding cellulitis, and occasionally associated constitutional symptoms. Nodules will rupture after several days, expelling pus and necrotic tissue. Furuncles are usually self-limited and resolve over days to weeks.[1,2,3]
  • Carbuncle: usually presents as an extremely painful lesion at the nape of the neck, the back or the thighs consisting of multiple coalescing furuncles. The lesion is red and indurated, with multiple pustules on the surface draining around several hair follicles. Fever and malaise are often present, and the patient may appear very ill. Can resolve slowly on its own leaving very dense and readily evident scars.[1]
Differential Diagnoses #
Diagnostic Workup #

Diagnosis of an abscess, furuncle, or carbuncle is usually made by taking a thorough history in conjunction with the clinical appearance of the lesion. Ultrasound can help confirm the diagnosis as well as clarify the depth and extent of infection.

Gram stain, culture, and sensitivities are recommended work-up in patients who require drainage, have recurrent lesions, or have signs of systemic infection.[4]

Treatment #

Application of heat to a simple abscess or furuncle can promote consolidation and may even aid in spontaneous drainage of lesion if done early enough in the course of the disease.[3] Incision and drainage (I&D) is usually curative for simple abscesses and furuncles.

Additional antibiotic coverage should be added if the patient failed prior treatment with I&D alone, if there is severe or extensive disease with multiple sites of infection, surrounding cellulitis or signs of systemic infection or inflammation (e.g., carbuncles) and in patients predisposed to SSTIs such as immunosuppressed patients. Antibiotics without I&D can be considered in areas in which I&D creates unwanted scarring or wounds that are difficult to manage (e.g., face, hands, and genitalia).[1]

Empiric oral antibiotics include dicloxacillin, cephalexin, and erythromycin, with clindamycin recommended for penicillin-allergic patients. Intravenous vancomycin is recommended for the most severe cases, though local sensitivity patterns should guide initial treatment and culture results can provide further guidance on therapy.[3]

Slide Viewer #
https://utahderm.med.utah.edu/image-viewer/
References #
  1. Miller, Lloyd S. “Superficial Cutaneous Infections and Pyodermas.” Fitzpatrick’s Dermatology, 9e Sewon Kang, et al. McGraw-Hill, 2019, https://accessmedicine-mhmedical-com.proxy.rvu.edu/content.aspx?bookid=2570&sectionid=210430286.
  2. Shinkai, Kanade, and Lindy P. Fox. “Furunculosis (Boils) & Carbuncles.” Current Medical Diagnosis & Treatment 2021  Maxine A. Papadakis, et al. McGraw-Hill, 2021, https://accessmedicine-mhmedical-com.proxy.rvu.edu/content.aspx?bookid=2957&sectionid=249365215.
  3. Meshkov, Lauren S., et al. “Bacterial Infections.” Taylor and Kelly’s Dermatology for Skin of Color, 2e  A. Paul Kelly, et al. McGraw-Hill, 2016, https://accessmedicine-mhmedical-com.proxy.rvu.edu/content.aspx?bookid=2585&sectionid=211767935.
  4. Hysell, K. (2020, December 7). Skin Abscesses, Furuncles, and Carbuncles. Retrieved April 07, 2021, from https://www.dynamed.com/condition/skin-abscesses-furuncles-and-carbuncles
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