You felt a slight itch on the back and eventually developed a huge tree like patch there. You have been concerned what it could be. You need to know how this may have occurred and what you need to do for this rash.
About pityriasis rosea
Pityriasis rosea is a skin rash that occurs in the middle of the body on the chest and abdomen, or the back. Beginning as a large spot it may enlarge to pine tree like shape. This distinct shape may be lost as the rash spreads, and the rash eventually may clear spontaneously. It commonly affects older children and young adults, though people of all ages can develop the disorder.
Pityriasis rosea begins as a large scaly patch on the chest or abdomen. This patch called the herald patch may follow an episode of an upper respiratory infection that may cause fever, sore throat, and headache. In a few weeks, other fine scaly spots may appear along the lines of the skin and look like a pine tree. These may itch. Small pink or grey scaly spots may also appear on the legs, arms, and face. The rash may worsen after physical activity and bathing in hot water.
Pityriasis rosacea is characterized by resolution of the rash over a period of time. The rash and other symptoms of pityriasis rosacea may last for six to eight weeks and then disappear. Sometimes these may last as long as 12 weeks.
Pityriasis rosacea may resemble other skin conditions like ringworm, eczema, syphilis, or psoriasis. Ringworm rash is round and has irregular active red edges and clearer center. Rash in eczema may be extremely itchy and may ooze tissue fluid. That in psoriasis is a symmetrically distributed rash that has red inflamed borders and is covered with shining silvery white scales and is too itchy. The rash in syphilis may affect the palms and soles, and is red or brown and non-itchy. Some medicines may cause a rash as an adverse reaction, and this rash may resemble that of pityriasis rosacea. A careful clinical examination is a must to distinguish the rash of pityriasis rosacea from any of these conditions.
Causes
The cause of pityriasis rosea is not known. It is believed to be caused by a virus as the illness is commonly seen in fall and spring, and may be preceded by symptoms like fever, headache and sore throat may resemble a viral illness. Viruses like the strains of the human herpes virus (HHV6 or HHV7) are said to be causative but the association is not certain. Pityriasis rosacea is not contagious and does not spread from one person to another, though more than one member in the family may be affected at one time.
Diagnosis
The typical appearance of the rash of pityriasis is diagnostic in most clinical situations. However, since the rash may resemble the rash of other illnesses, the doctor may advise a biopsy to confirm the diagnosis. In this, a small piece of the skin may be scraped or snipped to be examined under a microscope in the laboratory. A blood test may be needed to rule out syphilis.
Treatment
Pityriasis rosacea may not need treatment in mild cases. In moderate to severe cases, creams containing steroids may help to reduce itching and redness. Medicines called steroids act as anti-inflammatory agents and can relieve the symptoms. Oral medicines like cetirizine, fexofenadine, diphenhydramine, chlorpheniramine, clemastine, and loratadine are antihistaminics and help to relieve itching. Antiviral medicines like acyclovir and famciclovir may reduce the duration of pityriasis rosea by a week or two. Light therapy, called phototherapy, is done by exposing the affected skin to ultraviolet B (UVB) light or sunlight. Light therapy must be done only under supervision of a dermatologist or physician. It may be good to use lukewarm and not hot water for bath. The rash may be exaggerated by strenuous physical activity, and hence the same should be avoided for few weeks till the symptoms settle.
Prevention
There are no definite preventive measures known for pityriasis rosacea. Most cases of pityriasis eventually heal and the disease may not return ever in life. Hence prevention has no role in pityriasis rosacea. You are certainly relieved to know that your rash will resolve and may not return again. It is important to see a health professional to rule out other more severe conditions that the rash can be confused for. Seek medical help for your condition. Make sure you see a doctor if your rash does not resolve within three months.
