Pityriasis rosea
Encyclopedia
Pityriasis rosea is a skin rash
. It is non-dangerous but may inflict substantial discomfort on some people. Classically, it begins with a single "herald patch" lesion, followed in 1 or 2 weeks by a generalized body rash lasting about 6 weeks.
as a cause. Also, HHV-7 is frequently found in healthy individuals, so its etiologic role is controversial.
, nummular or discoid eczema
, drug eruption
s, other viral exanthem
s, and especially secondary syphilis
. A biopsy
of the lesions will show extravasated erythrocytes within dermal papillae and dyskeratotic cells within the dermis
.
Oral antihistamine
s or topical steroids may be used to decrease itching. Steroids do provide relief from itching, and improve the appearance of the rash, but they also cause the new skin that forms (after the rash subsides) to take longer to match the surrounding skin color. While no scarring has been found to be associated with the rash, itching and scratching should be avoided. It's possible that scratching can make itching worse and an itch-scratch cycle may develop with regular scratching (that is, you itch more because you scratch, so you scratch more because you itch, and so on). Irritants such as soaps with fragrances, hot water, wool, and synthetic fabrics should be avoided; a soap containing moisturizers (such as goat's milk) may be used, however, and any generic moisturizer can help to manage over-dryness. Calamine lotion may be soothing to the skin and reduce itching. Emulsifiers should be used instead of soaps, as emulsifiers are gentler on the skin and include cleansers, eliminating the need for soap.
Direct sunlight makes the lesions resolve more quickly. According to this principle, medical treatment with ultraviolet
light has been used to hasten resolution, though studies disagree whether it decreases itching or not. UV therapy is most beneficial in the first week of the eruption.
PR is not viewed as contagious
, though there have been reports of small epidemic
s in fraternity houses and military bases, schools and gyms.
Rash
A rash is a change of the skin which affects its color, appearance or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracked or blistered, swell and may be painful. The causes, and...
. It is non-dangerous but may inflict substantial discomfort on some people. Classically, it begins with a single "herald patch" lesion, followed in 1 or 2 weeks by a generalized body rash lasting about 6 weeks.
Signs and symptoms
The symptoms of this condition include:- An upper respiratory tract infectionUpper respiratory tract infectionUpper respiratory tract infections are the illnesses caused by an acute infection which involves the upper respiratory tract: nose, sinuses, pharynx or larynx...
may precede all other symptoms in as many as 69% of patients - A single, 2- to 10-cm oval red "herald" patch appears, classically on the abdomen. Occasionally, the "herald" patch may occur in a 'hidden' position (in the armpit, for example) and not be noticed immediately. The "herald" patch may also appear as a cluster of smaller oval spots, and be mistaken for acneAcneAcne is a general term used for acneiform eruptions. It is usually used as a synonym for acne vulgaris, but may also refer to:*Acne aestivalis*Acne conglobata*Acne cosmetica*Acne fulminans*Acne keloidalis nuchae*Acne mechanica...
. Rarely, it does not become present at all. - 7-14 days after the herald patch, large patches of pink or red, flaky, oval-shaped rash appear on the torso. In 6% of cases an inverse distribution may occur, with rash mostly on the extremities. The more numerous oval patches generally spread widely across the chest first, following the rib-line in a characteristic "christmas-tree" distribution. Small, circular patches may appear on the back and neck several days later. It is unusual for lesions to form on the face, but they may appear on the cheeks or at the hairline.
- About one-in-four people with PR suffer from mild to severe symptomatic itching. (Moderate itching due to skin over-dryness is much more common, especially if soap is used to cleanse the affected areas.) The itching is often non-specific, and worsens if scratched. This tends to fade as the rash develops and does not usually last through the entire course of the disease.
- The rash may be accompanied by low-grade feverFeverFever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, headacheHeadacheA headache or cephalalgia is pain anywhere in the region of the head or neck. It can be a symptom of a number of different conditions of the head and neck. The brain tissue itself is not sensitive to pain because it lacks pain receptors. Rather, the pain is caused by disturbance of the...
, nauseaNauseaNausea , is a sensation of unease and discomfort in the upper stomach with an involuntary urge to vomit. It often, but not always, precedes vomiting...
and fatigueFatigue (physical)Fatigue is a state of awareness describing a range of afflictions, usually associated with physical and/or mental weakness, though varying from a general state of lethargy to a specific work-induced burning sensation within one's muscles...
. Over-the-counter medications can help manage these.
Causes
The cause of pityriasis rosea is not certain, but its clinical presentation and immunologic reactions suggest a viral infectionVirus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
as a cause. Also, HHV-7 is frequently found in healthy individuals, so its etiologic role is controversial.
Diagnosis
Experienced practitioners may make the diagnosis clinically. If the diagnosis is in doubt, tests may be performed to rule out similar conditions such as ringworm, guttate psoriasisPsoriasis
Psoriasis is an autoimmune disease that appears on the skin. It occurs when the immune system mistakes the skin cells as a pathogen, and sends out faulty signals that speed up the growth cycle of skin cells. Psoriasis is not contagious. However, psoriasis has been linked to an increased risk of...
, nummular or discoid eczema
Eczema
Eczema is a form of dermatitis, or inflammation of the epidermis . In England, an estimated 5.7 million or about one in every nine people have been diagnosed with the disease by a clinician at some point in their lives.The term eczema is broadly applied to a range of persistent skin conditions...
, drug eruption
Drug eruption
In medicine, a drug eruption is an adverse drug reaction of the skin. Most drug-induced cutaneous reactions are mild and disappear when the offending drug is withdrawn. Drugs can also cause hair and nail changes, affect the mucous membranes, or cause itching without outward skin...
s, other viral exanthem
Exanthem
An exanthem is a widespread rash usually occurring in children. Exanthems can be caused by toxins or drugs, microorganisms, or can result from autoimmune disease.It can be contrasted with an enanthem.-Types:...
s, and especially secondary syphilis
Syphilis
Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; however, it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis...
. A biopsy
Biopsy
A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...
of the lesions will show extravasated erythrocytes within dermal papillae and dyskeratotic cells within the dermis
Dermis
The dermis is a layer of skin between the epidermis and subcutaneous tissues, and is composed of two layers, the papillary and reticular dermis...
.
Treatment
No treatment is usually required.Oral antihistamine
Antihistamine
An H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...
s or topical steroids may be used to decrease itching. Steroids do provide relief from itching, and improve the appearance of the rash, but they also cause the new skin that forms (after the rash subsides) to take longer to match the surrounding skin color. While no scarring has been found to be associated with the rash, itching and scratching should be avoided. It's possible that scratching can make itching worse and an itch-scratch cycle may develop with regular scratching (that is, you itch more because you scratch, so you scratch more because you itch, and so on). Irritants such as soaps with fragrances, hot water, wool, and synthetic fabrics should be avoided; a soap containing moisturizers (such as goat's milk) may be used, however, and any generic moisturizer can help to manage over-dryness. Calamine lotion may be soothing to the skin and reduce itching. Emulsifiers should be used instead of soaps, as emulsifiers are gentler on the skin and include cleansers, eliminating the need for soap.
Direct sunlight makes the lesions resolve more quickly. According to this principle, medical treatment with ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light has been used to hasten resolution, though studies disagree whether it decreases itching or not. UV therapy is most beneficial in the first week of the eruption.
Prognosis
In most patients, the condition lasts only a matter of weeks; in some cases it can last longer (up to six months). The disease resolves completely without long-term effects. Two percent of patients have recurrence.Epidemiology
The overall prevalence of PR in the United States has been estimated to be 0.13% in men and 0.14% in women. It most commonly occurs between the ages of 10 and 35. It is more common in spring.PR is not viewed as contagious
Contagious disease
A contagious disease is a subset category of infectious diseases , which are easily transmitted by physical contact with the person suffering the disease, or by their secretions or objects touched by them....
, though there have been reports of small epidemic
Epidemic
In epidemiology, an epidemic , occurs when new cases of a certain disease, in a given human population, and during a given period, substantially exceed what is expected based on recent experience...
s in fraternity houses and military bases, schools and gyms.
See also
- Pityriasis circinata - a localized form of pityriasis rosea that affects the axillae and groinGroinIn human anatomy, the groin areas are the two creases at the junction of the torso with the legs, on either side of the pubic area. This is also known as the medial compartment of the thigh. A pulled groin muscle usually refers to a painful injury sustained by straining the hip adductor muscles...
- PityriasisPityriasisPityriasis commonly refers to flaking of the skin. The word comes from the Greek πίτυρον "bran".-Classification:Types include:* Pityriasis alba* Pityriasis lichenoides chronica* Pityriasis lichenoides et varioliformis acuta...
- for list of similarly named flaky skin conditions - List of cutaneous conditions