cyst protrudes out. Pilonidal cysts often remain
symptomless, though many become apparent
because they are subject to persistent irritation
from clothing, movement, and pressure. Extended
sitting, clothes that fit tightly across the buttocks,
and activities such as bicycling often create aware-
ness of pilonidal cysts.
The key symptoms of pilonidal disease are PAIN,
swelling, erythema (redness), and drainage (pus)
over the sacrum (tailbone). Often a FEVERaccom-
panies these symptoms, and the person is unable
to sit or walk without great discomfort. The doctor
often can diagnose pilonidal disease based on the
appearance of the cysts and the history of the
symptoms. The doctor typically lances (cuts open
with a sterile instrument) the cysts to allow them
to drain. Large, purulent, or recurrent cysts may
require surgery to remove them.
Pilonidal disease tends to be recurrent and per-
sistent, often continuing throughout life. Surgi-
cally removed cysts seldom return, though new
cysts frequently form in the same proximity.
Keeping the area clean and wearing loose-fitting
clothing can help prevent pilonidal cysts from
becoming irritated. Frequent position changes
when sitting and sitz baths (sitting in warm water)
help reduce discomfort when cysts are present.
See also ABSCESS; ANAL FISSURE.
pityriasis rosea A common SKIN RASHin which
an outbreak of lesions occurs and resolves over a
period of 3 to 12 weeks, generally without treat-
ment or complications. The lesions are characteris-
tically oval with distinct borders and may be
smooth (macules), raised (papules), or scaly
(plaques). Often the lesions itch and sometimes
they cause the skin to be hypersensitive to touch.
Doctors believe a VIRUScauses pityriasis rosea.
Symptoms and Diagnostic PathThe primary symptom of pityriasis rosea is an
itchy (pruritic) rash that appears on the back,
chest, arms, and legs. There is usually an initial
outbreak, called a herald LESION, with subsequent
eruptions of lesions in other locations. Often the
dermatologist will biopsy a lesion to confirm the
diagnosis, as well as conduct BLOODtests to rule
out secondary SYPHILIS, which has a rash very simi-
lar to that of pityriasis rosea.
Pityriasis rosea is very similar in
appearance to the rash that occurs with
secondary SYPHILIS. As untreated
syphilis has serious health conse-
quences, the diagnostic path should
include a blood test to rule out syphilis.Treatment Options and Outlook
Treatment aims to relieve symptoms. Cool baths
and skin moisturizers often are enough to relieve
mild pityriasis rosea. Topical and oral ANTIHISTAMINE
MEDICATIONS, and sometimes mild CORTICOSTEROID
MEDICATIONS, are necessary to control itching. The
lesions clear up on their own after about 8 weeks,
though in some people the rash and itching may
persist for up to 12 weeks.Risk Factors and Preventive Measures
Doctors do not know what causes pityriasis
though strongly suspect a virus. Outbreaks tend to
occur among people who are in close proximity,
commonly during the winter months. Complica-
tions are very uncommon though scratching can
open the lesions and allow secondary infection to
develop. Pityriasis rosea is a self-limiting condition
so recovery is without residual effects.
See alsoMACULE; PAPULE; PLAQUE, SKIN; PRURITUS;
PSORIASIS; TINEA INFECTIONS.plaque, skin Raised, hardened, scaly lesions that
form on the SKIN. Plaques characterize numerous
dermatologic conditions. They may itch, hurt, or
flake and may occur in small clusters or cover
large areas of skin. Treatment for skin plaques tar-
gets the underlying conditions and includes meas-
ures to moisturize or soften the skin to help
reduce the plaques. Topical CORTICOSTEROID MEDICA-
TIONS or injections of corticosteroids into large
plaques may help reduce them more quickly.
See also DERMATITIS; LESION; MACULE; NODULE;
PAPULE; PSORIASIS; SCALE.pressure sore See DECUBITUS ULCER.prurigo A chronic condition in which lesions,
typically papules or nodules, that itch intensely
erupt on the SKIN. The lesions may occur any-
where on the body, though typically form in loca-186 The Integumentary System