C

callus An accumulation of keratocytes that form
a thickened area of SKINin response to repeated
friction or pressure, typically at the site of
repeated blistering. A callus may be a different
color than the surrounding skin, often grayish or
yellowish. Calluses are most likely to develop on
the palms, fingers, fingertips, heels, and balls of
the feet. Most calluses are not painful and help
protect the skin from blisters and other friction-
related injuries. Calluses do not require medical
intervention unless they cause PAIN. Applying aloe
or a moisturizing skin lotion and gently rubbing
the callus with a pumice stone while in the
shower or bath are measures that can contain the
size and thickness of calluses. Wearing gloves to
protect the hands and well-fitting socks to protect
the feet can help prevent a BLISTERand resulting
callus from forming.
See also CORNS; KERATOCYTE.

carbuncle Clusters of infected HAIR follicles
(furuncles) that often form an ABSCESS. Carbuncles
are most common on the back of the neck and
shoulders, though may form at other locations
where furuncles tend to occur. Carbuncles are
painful and often result in FEVER and general
malaise (not feeling well). The INFECTIONis deep
within the layers of SKINand generally requires
treatment with an oral ANTIBIOTIC MEDICATION. The
doctor may choose to lance (open with a sterile
incision) the carbuncle to allow the collected pus
to drain. Applying warm, moist compresses four to
six times a day helps open the follicles and allow
continued drainage as HEALINGtakes place.
Though poor PERSONAL HYGIENEcan contribute to
the development of furuncles and carbuncles, the
primary cause of these painful sores is BACTERIA,
typically Staphylococcus, that normally resides on

the skin. Carbuncles tend to recur. People who

have DIABETESare more likely to develop carbun-

cles because the diabetes damages the delicate

blood vessels responsible for peripheral circula-

tion, preventing the bloodstream from carrying

bacteria-fighting blood cells to the site of the

infection. People who have impaired immune

function are also at increased risk. Untreated car-

buncles can result in scars after healing or can

progress to systemic infection (SEPTICEMIA).

See also CELLULITIS; FURUNCLE; SCAR.

cellulitis INFLAMMATIONof the inner layers of the

SKINand the underlying connective tissues, usually

the result of a bacterial INFECTION. People who

have PERIPHERAL VASCULAR DISEASE(PVD), DIABETES,

or other health conditions that impair BLOODcircu-

lation have increased risk for cellulitis. Cellulitis

develops when a break in the skin, such as a cut

or an insect bite or sting, allows BACTERIAnormally

present on the surface of the skin to enter and

establish infection. The offending breach often

comes from something so small as to appear

insignificant until infection sets in. Staphylococcusis

the most common type of bacteria responsible for

cellulitis; Streptococcus is sometimes responsible.

Bacteria also may enter via contamination of a

penetrating object such as a splinter. Cellulitis

requires prompt treatment with ANTIBIOTIC MEDICA-

TIONSto minimize tissue damage and prevent the

spread of infection.

Symptoms and Diagnostic Path

Swelling, redness, and PAINor itching are the key

symptoms of cellulitis. The edges of the infection

are diffuse, often making it difficult to establish a

border between healthy and infected tissue. The

doctor diagnoses cellulitis primarily on its appear-

143