pityriasis rosea

Pityriasis Rosea 

Definition

Pityriasis rosea is a mild, noncontagious skin disorder common among children and young adults, and characterized by a single round spot on the body, followed later by a rash of colored spots on the body and upper arms.

Description

Pityriasis rosea is most common in young adults, and appears up to 50% more often in women. Its cause is unknown; however, some scientists believe that the rash is an immune response to some type of infection in the body.

Causes and symptoms

Doctors do not think that pityriasis rosea is contagious, but the cause is unknown. Some experts suspect the rash, which is most common in spring and fall, may be triggered by a virus, but no infectious agent has ever been found.

It is not sexually transmitted, and does not appear to be contagious from one person to the next.

Sometimes, before the symptoms appear, people experience preliminary sensations including fever, malaise, sore throat, or headache. Symptoms begin with a single, large round spot called a "herald patch" on the body, followed days or weeks later by slightly raised, scaly-edged round or oval pink-copper colored spots on the trunk and upper arms. The spots, which have a wrinkled center and a sharp border, sometimes resemble a Christmas tree. They may be mild to severely itchy, and they can spread to other parts of the body.

Diagnosis

A physician can diagnose the condition with blood tests, skin scrapings, or a biopsy of the lesion.

Treatment

The rash usually clears up on its own, although a physician should rule out other conditions that may cause a similar rash (such as syphilis).

Treatment includes external and internal medications for itching and inflammation. Mild inflammation and itching can be relieved with antihistamine drugs or calamine lotion, zinc oxide, or other mild lubricants or anti-itching creams. Gentle, soothing strokes should be used to apply the ointments, since vigorous rubbing may cause the lesions to spread. More severe itching and inflammation is treated with topical steroids. Moderate exposure to sun or ultraviolet light may help heal the lesions, but patients should avoid being sunburned.

Soap makes the rash more uncomfortable; patients should bathe or shower with plain lukewarm water, and apply a thin coating of bath oil to freshly-dried skin afterwards.

Key terms

Antihistamines — A group of drugs that block the effects of histamine, a chemical released during an allergic reaction.

Steroids — A group of drugs that includes the corticosteroids, similar to hormones produced by the adrenal glands, and used to relieve inflammation and itching.

Prognosis

These spots, which may be itchy, last for 3-12 weeks. Symptoms rarely recur.

Resources

Organizations

American Academy of Dermatology. 930 N. Meacham Road, P.O. Box 4014, Schaumburg, IL 60168-4014. (847) 330-0230. Fax: (847) 330-0050. http://www.aad.org.

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pityriasis /pit·y·ri·a·sis/ (pit″ĭ-ri´ah-sis) any of various skin diseases characterized by the formation of fine, branny scales.

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pityriasis al´ba  a chronic condition with patchy scaling and hypopigmentation of the skin of the face.

pityriasis ro´sea  a dermatosis marked by scaling, pink, oval macules arranged with the long axes parallel to the cleavage lines of the skin.

pityriasis ru´bra pila´ris  a chronic inflammatory skin disease marked by pink scaling macules and horny follicular papules, beginning usually with seborrhea of the scalp and face, with keratoderma of palms and soles.

pityriasis versi´color  tinea versicolor.

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pityriasis ro·se·a (rs-, -z-)

n.

A self-limited eruption of macules or papules involving principally the trunk and extremities.

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pityriasis rosea,

a self-limited skin disease in which a slightly scaling pink macular rash spreads over the trunk and other unexposed areas of the body. A characteristic feature is the herald patch, a larger, more scaly lesion that precedes the diffuse rash by several days. The smaller lesions tend to line up with the long axis parallel to normal lines of cleavage of the skin. Mild itching is the only symptom. The disease lasts 4 to 8 weeks and rarely recurs. Compare pityriasis alba.

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pityriasis [pit″ĭ-ri´ah-sis]

any of various skin diseases characterized by the formation of fine, branny scales.

acute lichenoid pityriasis an acute or subacute, sometimes relapsing, widespread macular, papular, or vesicular eruption that tends to crusting, necrosis, and hemorrhage; when it heals it leaves pigmented depressed scars, followed by a new crop of lesions. Progression to the chronic lichenoid form occasionally occurs.

pityriasis al´ba a chronic condition with patchy scaling and hypopigmentation of the skin of the face.

chronic lichenoid pityriasis a chronic brown to red-brown scaly macular eruption, seen mainly on the trunk, with epidermal changes and a perivascular lymphocytic infiltrate. It may arise independently or happen as a progression of the acute lichenoid form.

pityriasis ro´sea a common acute or subacute, self-limited exanthematous disease of unknown etiology. It begins with a solitary red to tan plaque (herald plaque), usually on the trunk, arms, or thighs, which is followed by similar but smaller papular or macular lesions; these later may peel and leave a scaly collarette.

pityriasis ru´bra pila´ris a chronic inflammatory skin disease marked by pink scaling macules and cone-shaped horny follicular papules; it usually begins with severe seborrhea of the scalp and face, associated with keratoderma of palms and soles.

pityriasis versi´color tinea versicolor.

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pityriasis rosea (pitrī´sis rō´zē),

n a noncontagious skin disease with reddish, scaly patches and moderate fever.

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pityriasis

a group of skin diseases in humans characterized by branlike scales on the skin surface. The skin is not thickened and its surface is unbroken. Pityriasis rosea of pigs is the only diseases in animals that is similar.

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pityriasis rosea

a disease of pigs, most commonly white breeds such as Landrace, up to 3 months old characterized by circular lesions 1 inch (2-3 cm) diameter which often coalesce to produce large irregular lesions. The central area of the lesion is an area of comparatively normal skin, covered by thin brown scales and surrounded by a very narrow, 1 to 2 mm raised zone of erythema. There is no irritation or no bristle loss and spontaneous recovery is usual. The etiology is unknown. Called also porcine juvenile pustular psoriasiform dermatitis, pseudoringworm.

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pityriasis rosea

Dermatology A skin condition, most common in young adults, with a 3:2 ♀:♂ ratio, seen in the fall and spring, lasting 4 to 8 wks, manifest as a single larger patch called a herald patch followed several days later by more rash. See GLC7.