The term boil comes from Latin and means “little thief”. A boil is a deep, painful inflammation that originates from the hair follicle and then spreads to the surrounding tissue. In the middle, the skin tissue begins to die off after some time (medical term: necrosis, a kind of cell death) and a central melting down consisting of pus is found.
This creates a so-called plug, which can break through the surface of the skin, causing the pus to empty spontaneously. Afterwards the boil heals and scars are formed. In principle, boils can occur anywhere on the hairy skin, but they are mainly found in the regions of the face and neck, armpits, genital area, buttocks and thighs.
If two or more boils merge with each other, a large-area, very painful carbuncle develops. If furuncles occur in the affected person in batches or repeatedly, this is called furunculosis. Furuncles belong to the five most frequent skin diseases in the facial region.
Furuncles are caused by bacteria, mostly by those of the Staphylococcus aureus strain, sometimes also by a mixed flora. These bacteria can infect the hair follicle by penetrating the skin. This usually only happens in people who have a weakened immune system for various reasons (e.g. in the presence of another disease or when treated with immunosuppressive drugs such as cortisol).
Then the pathogens can enter the skin along the hair follicles or sweat glands through small skin lesions, which are usually not even visible to the naked eye. Staphylococci often come from the nasopharynx, where they are physiologically present and largely harmless. This strain of bacteria is able to produce enzymes that cause the tissue to loosen up, which further promotes the spread of the inflammation.
Particularly susceptible to the development of furuncles are patients with insufficiently controlled or unrecognized diabetes mellitus (diabetes) or kidney disease. In addition, there are some skin diseases, first of all impetigo (an infectious skin disease occurring mainly in small children) and sycosis (a chronic inflammation of hair follicles), but also purulent diseases of other organs and the resulting blood poisoning (septicaemia), which can lead to the formation of furuncles. Favouring factors are also the wearing of too tight-fitting, abrasive clothing and insufficient disinfection of the skin after shaving.
Very often, however, boils also occur spontaneously, individually or in clusters, without any recognizable cause. The symptoms of a boil are always visible in the area of the infected hair follicle. The first sign of a developing boil is a tiny red pustule at the site of origin of the hair follicle inflammation.
Only if you look very closely, you can see a small hair in the middle of it, which may already be surrounded by a swelling. The inflammation then spreads to the surrounding tissue, only now is it called a boil by definition. This is a pressure-sensitive, tense and painful lump, which usually reaches a diameter of between half a centimeter and two centimeters.
As the furuncle matures further, tissue dies off in its center (necrosis) and a purulent fusion forms the central plug. At some point, the furuncle finally breaks through the skin so that the pus is released to the outside. The skin can then heal again, leaving a small retracted scar.
Carbuncles represent a larger-area inflammation in which the subcutaneous tissue is also affected and which therefore often causes more severe symptoms. On the one hand, they are usually more painful than individual boils. In addition, general symptoms such as increased temperature, chills or fatigue are sometimes also present.
In very severe cases, the lymph nodes may swell or even inflame the lymphatic system (lymphangitis). In addition, if the bacteria enter the bloodstream, there is a risk of life-threatening blood poisoning (sepsis, septicaemia). If furuncles are located in the face above the upper lip, germs can be carried into the interior of the skull, which can cause orbital thrombosis (a disease of the orbit) or even life-threatening cerebral venous thrombosis or meningitis with the corresponding symptoms. The diagnosis of a furuncle is made after detailed examination of the affected skin areas.In addition, a smear test can be used to detect the exact pathogen in the laboratory. If suspected, the diagnosis can also include a determination of blood sugar, since undetected diabetes mellitus is an important risk factor for the development of furuncle.
