Psoriasis and pityriasis rosea are both common conditions that can cause scaly patches on the skin. However, the causes and other symptoms of these conditions are different.
Psoriasis is a chronic, lifelong autoimmune condition with no cure, while pityriasis rosea is temporary and generally clears up within a few weeks.
The symptoms of psoriasis can also resemble those of other skin conditions, including fungal infections, acne, and eczema.
In this article, we examine how to identify psoriasis and pityriasis rosea. We also discuss the causes and treatment of each of these conditions.
Psoriasis is an autoimmune disease that causes inflamed, dry, red or gray, and scaly patches to develop on the skin. More than 8 million Americans have psoriasis.
People with psoriasis tend to experience flare-ups with periods of remission between them. There is no cure for the condition, but there are ways to manage it.
There are several types of psoriasis,
- Plaque psoriasis: This causes dry, raised, red or gray plaques that can be itchy and painful.
- Guttate psoriasis: This occurs due to bacterial infection and causes small, scaling lesions in the shape of water drops. Once the infection has gone, it usually resolves without treatment.
- Inverse psoriasis: This affects the areas within folds of skin and may develop due to a fungal infection.
- Pustular psoriasis: Red or discolored skin surrounds white pustules or blisters, usually on the hands and feet. Despite its appearance, this form of psoriasis is not an infection and is not contagious.
- Erythrodermic psoriasis: This is a severe form of psoriasis that produces a fiery redness over most of the body. Symptoms include severe itching and pain, and the skin often peels off in sheets. It is rare and generally occurs in people with plaque psoriasis.
People may mistake plaque psoriasis or guttate psoriasis for pityriasis rosea.
Pityriasis rosea is another skin condition that causes scaly patches of rash on the skin. It tends to present initially with a large patch of rash, which is called the herald or mother patch. Smaller patches called daughter patches then follow.
The large patch usually appears on the chest, back, or abdomen, but it can develop anywhere on the skin.
Pityriasis rosea is most common in people between the ages of 10 and 35 years, but it is also more likely to occur during pregnancy.
Pityriasis rosea clears up on its own and is not serious.
Neither psoriasis nor pityriasis rosea is contagious, so these conditions will not spread between people.
Psoriasis and pityriasis rosea both cause patches of scaly, red or gray skin, but the patches form different patterns. The conditions also progress differently.
Symptoms that are specific to psoriasis include:
- red or gray, inflamed, raised patches of skin with a covering of thick, silvery scales
- small areas of scaly skin
- dry skin that may crack or bleed, itching, burning, and pain around the patches
- thick, pitted, and ridged fingernails or toenails
- swollen and painful joints, if a person has psoriatic arthritis
The symptoms of pityriasis rosea include:
- a mother patch, which is a large, scaly patch of skin that appears violet or dark gray on dark skin and pink on lighter skin
- multiple smaller daughter patches on the chest, abdomen, back, arms, and legs that appear 1 to 2 weeks after the mother patch
- flu-like symptoms, such as fatigue, headache, and fever
Doctors do not know what causes psoriasis exactly, but they believe that it is an autoimmune condition that may have a genetic component.
They are also unsure why pityriasis rosea occurs. This condition is not an allergy and does not develop due to fungi or bacteria. It may be the result of a virus.
While specific triggers, such as infection, stress, and certain lifestyle factors, can prompt a psoriasis flare, there are no known triggers for pityriasis rosea.
Psoriasis may need short-term or long-term treatment, depending on the type and how severe the symptoms are.
Treatment options include:
- topical corticosteroids for inflammation and itching
- moisturizers for dry skin
- coal tar products to remove scales and soften the skin
- salicylic acid for scaling
- light therapy
Systemic medications work throughout the body. A person can take them as injections or by mouth. They include methotrexate, cyclosporine, and some types of retinoids.
Depending on the type of psoriasis and the severity of symptoms, a doctor may prescribe a biologic medicine. This is a long-term treatment that may help reduce the risk of flares and the severity of symptoms. Examples include etanercept (Enbrel) and infliximab (Remicade).
Pityriasis rosea usually resolves without treatment within 6 to 8 weeks. If necessary, a doctor may prescribe an anti-itch cream for severe itching.
Pityriasis rosea is not a severe condition, and it often resolves without leaving a trace. However, people with signs of pityriasis rosea still need to visit a doctor to rule out other conditions. If they are experiencing severe itching, they can also ask for a prescription cream to provide relief.
People with symptoms of psoriasis need to visit a doctor for diagnosis and treatment. Anyone who also has any signs of infections, such as pain, swelling, or fever, should seek immediate medical care.
People may sometimes mistake psoriasis and pityriasis rosea for other conditions, including:
- eczema
- nummular dermatitis
- ringworm
- dandruff
- acne
Psoriasis and pityriasis rosea cause similar patches of scaly, red, or gray skin, but they are separate conditions with different causes.
Psoriasis is a chronic, autoimmune condition that it is possible to manage but not cure.
Pityriasis rosea is a skin condition without a known cause. It typically goes away on its own within 2 months.