A carbuncle is a cluster of

boil A boil, also called a furuncle, is a deep folliculitis, which is an infection of the hair follicle. It is most commonly caused by infection by the bacterium '' Staphylococcus aureus'', resulting in a painful swollen area on the skin caused by ...

s caused by

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were am ...

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...

, most commonly with ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often posit ...

'' or ''

Streptococcus pyogenes ''Streptococcus pyogenes'' is a species of Gram-positive, aerotolerant bacteria in the genus '' Streptococcus''. These bacteria are extracellular, and made up of non-motile and non-sporing cocci (round cells) that tend to link in chains. They ...

''. The presence of a carbuncle is a sign that the

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...

is active and fighting the infection. The infection is

contagious Contagious may refer to: * Contagious disease Literature * Contagious (magazine), a marketing publication * ''Contagious'' (novel), a science fiction thriller novel by Scott Sigler Music Albums *''Contagious'' (Peggy Scott-Adams album), 1997 ...

and may spread to other areas of the body, or other people; those living in the same residence may develop carbuncles at the same time. In the early 21st century, infection involving methicillin-resistant ''Staphylococcus aureus'' (MRSA) has become more common.

Signs and symptoms

A carbuncle is a cluster of several

s, which is typically filled with purulent exudate (dead

neutrophils Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying ...

, phagocytized bacteria, and other cellular components). Fluid may drain freely from the carbuncle, or intervention involving an incision and drainage procedure may be needed. Carbuncles may develop anywhere, but they are most common on the back and the nape of the

neck The neck is the part of the body on many vertebrates that connects the head with the torso. The neck supports the weight of the head and protects the nerves that carry sensory and motor information from the brain down to the rest of the body. In ...

. A carbuncle is palpable and can range in size to be as small as a

pea The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds and d ...

or as large as a golf ball. The surrounding area is

indurated Friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under duress or contact, especially by rubbing. The opposite of friable is indurate. Substances that are designated hazardous, ...

. Later, skin on the centre of the carbuncle softens and peripheral satellite

vesicle Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry) In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form nat ...

s appear; these rupture, discharging pus, and give rise to

cribriform Cribriform (Latin for "perforated") can refer to: * Cribriform plate In mammalian anatomy, the cribriform plate (Latin for lit. ''sieve-shaped''), horizontal lamina or lamina cribrosa is part of the ethmoid bone. It is received into the ethmoi ...

appearance. As the impending infection develops,

itching Itch (also known as pruritus) is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of sensory experience. Itch has many similarities to pain, and while both are unpleasan ...

may occur. There may be localized erythema or skin irritation, and the area may be painful when touched. Sometimes more severe symptoms may occur, such as

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...

chills Chills is a feeling of coldness occurring during a high fever, but sometimes is also a common symptom which occurs alone in specific people. It occurs during fever due to the release of cytokines and prostaglandins as part of the inflammatory ...

, and general

malaise As a medical term, malaise is a feeling of general discomfort, uneasiness or lack of wellbeing and often the first sign of an infection or other disease. The word has existed in French since at least the 12th century. The term is often used ...

as the body fights the infection.

Cause

The initial cause of a carbuncle can often not be determined. Triggers that make carbuncle infections more likely include recent incidence of

folliculitis Folliculitis is the infection and inflammation of one or more hair follicles. The condition may occur anywhere on hair-covered skin. The rash may appear as pimples that come to white tips on the face, chest, back, arms, legs, buttocks, or head. A ...

; friction from clothing or shaving; having hair pulled out, such as sites where clothing or furniture grab at hairs; generally poor

hygiene Hygiene is a series of practices performed to preserve health. According to the World Health Organization (WHO), "Hygiene refers to conditions and practices that help to maintain health and prevent the spread of diseases." Personal hygiene refer ...

; poor nutrition; or weakened

immunity Immunity may refer to: Medicine * Immunity (medical), resistance of an organism to infection or disease * ''Immunity'' (journal), a scientific journal published by Cell Press Biology * Immune system Engineering * Radiofrequence immunity de ...

. Poor health may be a predisposing factor – for example, persons with

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

and immune system diseases are more likely to develop infections (especially bacterial infections of the leg or foot).

Society and culture

Etymology

The word is believed to have originated from the Latin: ''carbunculus'', originally a small coal; diminutive of ''carbon-'', ''carbo'': charcoal or ember, but also a carbuncle stone, "precious stones of a red or fiery colour", usually

garnet Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different ...

Metaphor: the "monstrous carbuncle"

In 1984

Charles III Charles III (Charles Philip Arthur George; born 14 November 1948) is King of the United Kingdom and the 14 other Commonwealth realms. He was the longest-serving heir apparent and Prince of Wales and, at age 73, became the oldest person ...

, then Prince of Wales, described the proposed Sainsbury Wing extension to the

National Gallery The National Gallery is an art museum in Trafalgar Square in the City of Westminster, in Central London, England. Founded in 1824, it houses a collection of over 2,300 paintings dating from the mid-13th century to 1900. The current Director ...

in London as a "monstrous carbuncle on the face of a much-loved and elegant friend", a term he has used since to describe other pieces of architecture.

References

{{Bacterial cutaneous infections Gross pathology ca:Àntrax pl:Czyrak