Pityriasis rosea describes a skin rash that most commonly affects people between the ages of 10 and 35, according to the American Academy of Dermatology. In the early stages, doctors may confuse the rash with other skin disorders, but as the rash spreads, it takes on a distinctive appearance. Although the occurrence, duration and extent of the rash may alarm the patient, it does not cause any permanent marks or damage.
Cause
Although the exact cause of pityriasis rosea remains unknown, doctors have concluded it does not occur due to a fungus, bacterial infection or allergy. Clinical evidence outlined in a study published by Chuh and associates in Epidemiology and Infection supports current theories that the rash occurs as a result of a viral infection. Doctors have not yet identified the specific virus causing the rash, but the fact that the rash follows a specific programmed clinical course, the lack of recurrence and spontaneous resolution suggests a virus, or group of viruses as the most likely cause.
Symptoms
Pityriasis rosea begins with one large scaly patch of skin usually found on the back, chest or abdomen. Many patients often mistake this patch, called the herald patch or mother patch, as ringworm, because it resembles this common fungal infection. The rash often feels itchy, which can worsen when the patient becomes warm, such as during exercise. Some patients also experience symptoms of an upper respiratory infection including a headache, stuffy nose, sore throat and mild fever, according to MayoClinic.com.
Location
During the first few weeks, the rash begins to spread throughout the trunk, arms and legs. Small scaly pink patches may appear on the neck, arms, legs, abdomen and back. As the rash spreads, it often forms a pattern resembling a Christmas tree, as described by the American Academy of Dermatology. The rash rarely affects the face.
Treatment
Pityriasis rosea usually resolves on its own without any treatment. For those patients who experience moderate to severe itching, external medicated lotions such as steroid creams can help to relieve the symptoms. In severe cases, a dermatologist can administer ultraviolet light therapy to help clear the rash. Oral antihistamines, such as the prescription medications cetirizine and fexofenadine and the over-the-counter medication diphenhydramine, can help to relieve itching as well. Oral steroid medications, such as corticosteroids, also can help to reduce any inflammation and relieve the itching.
Duration
Pityriasis rosea typically follows a distinct clinical course. Patients usually experience remission, or the disappearance of symptoms, within eight weeks after the onset of the herald patch. For some patients, the rash remains for up to 12 weeks, as reported by Chuh in Epidemiology and Infection. The good news remains, no matter how extensive the rash or how severe the itching, pityriasis rosea eventually goes away even without treatment.
