Skin-nontumor / Clinical dermatology
Infectious disorders
Carbuncle

Author: Ha Kirsten Do, M.D. (see Authors page)

Revised: 20 May 2016, last major update September 2010

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Carbuncle

Definition / General
  • Deep form of bacterial folliculitis involving several hair follicles, often due to Staphylococcus aureus, which can be cultured from skin
Terminology
  • Also known as boils
  • Furuncle: small abscess exuding purulent material, involving skin and subcutis in areas with hair follicles
  • Carbuncle: aggregate of connected furuncles, involves multiple hair follicles
Epidemiology
  • Most individuals with carbuncles are otherwise healthy and have good personal hygiene, but they are among the 10 - 20% of population that are Staphylococcus aureus carriers on surface of skin
  • Common in obese patients
  • Carbuncles may occur in patients with immune deficiency, anemia, diabetes or iron deficiency
Sites
  • Staphylococcus aureus is most commonly found in intertriginous regions (where two skin areas may touch or rub together) of nostrils, armpits, groin and intergluteal cleft
Etiology
  • Staphylococcus aureus is present in patients in intertriginous regions, but may be transferred to other sites by scratching
  • Tiny nicks or scratches in the skin can inoculate the bacteria into the wall of a hair follicle, a weak point in the skin
  • Once innoculated, bacteria cause a boil, which runs its usual infectious course in about 10 days
Clinical Features
  • Painful localized bacterial infection of skin and subcutis, usually with several openings through which pus is discharged
  • Tender, swollen red papules or pustules
Treatment
  • Antiseptic cleanser, like povidone-iodine or chlorhexidine is used daily for several weeks to clean carbuncle
  • Topical antibiotics include erythromycin BID and clindamycin BID to affected area until clear

  • Note: verify current drug dosages before use (eMedicine)

  • Oral antibiotics include:
    • Cephalexin (adult) 1 - 4 g/day divided BID or QID x 10 - 14 days; (children) 25 - 50 mg/kg/day PO divided q6H for mild to moderate infection; 50 - 100 mg/kg/day divided q6H for severe infection; not to exceed 4g/day for any age
    • Dicloxacillin (adult or children > 40 kg) 125 - 500 mg q6h x 10 - 14 days; (children < 40 kg): 12.5 - 50 mg/kg/d PO divided q6h
    • Erythromycin (adult) 500 mg BID or 330mg q8hr x 10 - 14 days
    • Clindamycin (adult) 150 - 450 mg q6 - 8h x 10 - 14 days; (children) 10 - 30 mg/kg/day q6 - 8h
    • Minocycline (adult) 100 mg BID x 10 - 14 days
    • Rifampin (adult) 600 mg qD x 10 days; (children) 15 mg/kg/day divided BID x 10 days
    • Ciprofloxacin (adult): 250 - 750 mg BID x 10 - 14 days

  • In recurrent cases, obtain nasal culture of patient and family members to look for Staphylococcus aureus colonization
  • If patient is Staphylococcus aureus nasal carrier, consider applying topical antibiotic like mupirocin ointment to nostrils twice daily for 5 days (Wikipedia)
  • If family members are nasal carriers, consider mupirocin ointment or rifampin 600 mg daily for 10 days
  • Consider checking nasal swab for MRSA or culture for sensitivity for treatment failure

  • Prevention:
    • Good hygiene including bathing, hand-washing, keeping nails short and clean
    • Avoid close shaving until lesions are completely resolved
    • Change disposable razors daily or clean electric razor heads daily
    • Wear loose-fitting clothes (tight-fitting clothes may cause occlusion); change clothes daily

  • In obese patients, weight reduction will be beneficial
Clinical Images

Images hosted on other servers:

Various images

Micro Description
  • Inflammatory cells, predominantly neutrophils, within the wall and ostia of the hair follicle, creating a follicular-based pustule
  • Inflammation can be either limited to the superficial follicle, primarily involving the infundibulum, or can affect both the superficial and deep aspects of the follicle
  • Deep folliculitis can arise from the chronic lesions of superficial folliculitis or from lesions that are manipulated or scratched; may cause scarring
Differential Diagnosis