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Skin-nontumor / Clinical Dermatology

Infectious disorders


Reviewer: Ha Kirsten Do, M.D., IUPUI (see Reviewers page)
Revised: 2 November 2010, last major update September 2010
Copyright: (c) 2002-2010, PathologyOutlines.com, Inc.


● Deep form of bacterial folliculitis involving several hair follicles, often due to Staphylococcus aureus, which can be cultured from skin


● 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


● 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


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


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


● Painful localized bacterial infection of skin and subcutis, usually with several openings through which pus is discharged


● 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

● 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 description

● Tender, swollen red papules or pustules

Clinical images


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

Virtual slides


Differential diagnosis

Abscess / furuncle
Folliculitis: tender pustule that involves the hair follicle
Irritated epidermal inclusion cyst

End of Skin-nontumor / Clinical Dermatology > Infectious disorders > Carbuncle

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