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Skin rashes are a huge part of what comprises medical dermatology.  Often patients present to Dr. Green’s office because they have a new rash, which is red, pruritic, or painful.  Many rashes are a sign of systemic disease or other pathology.  Skin rashes such as Pityriasis Rosea, Psoriasis, Lichen Planus, eczema, syphilis, drug eruptions, and tinea corporis, can be difficult to distinguish.  It is very important that if you have a new skin rash to consult an expert in dermatology, like Dr. Michele Green, to examine, treat, and even biopsy the eruption.  Dr. Green is one of the best diagnosticians in medical dermatology, and is frequently consulted on various dermatological rashes in her NYC private office.

What Is Pityriasis Rosea?

Pityriasis Rosea is a common skin disorder. It is a skin rash which is typically seen on the chest, arms, neck, or thighs. The first sign of the eruption is referred to as a herald patch, which is a single 2 to 5 cm red oval patch which typically appears on the abdomen. Often several days after the original herald patch, multiple smaller patches or plaques will start to appear across the back.  These plaques usually follow the cleavage lines on both sides of the upper trunk. This distribution has been described as appearing like a Christmas tree. The rash of Pityriasis Rosea does not involve the palms or soles, face, or scalp.  The lack of involvement in these areas is a key factor in distinguishing it from other skin rashes.

While the rash generally goes away on its own within ten weeks, there are several treatments available to help alleviate the symptoms.

Who Can Get Pityriasis Rosea?

Pityriasis Rosea can occur at any age, however, it’s most commonly seen in children, teens and young adults between the ages of 10 to 35.  It is not believed to be contagious.

What are the Symptoms of Pityriasis Rosea?

Pityriasis Rosea usually begins with a large, scaly patch, known as the herald patch, or mother patch. This patch can be noticed on your chest, upper arms, back or abdomen. Before the herald patch develops, many patients may experience a sore throat or flu-like symptoms. Additional symptoms can develop such as fatigue, swollen lymph nodes, nausea or insomnia. Mild, itching can occur as well.

Patients with fair skin may notice the herald patch to be pink or flesh colored and is covered with a fine white scale trailing inside the edge of the lesion, like a collarette.  In patients with darker skin types, the patch will seem almost purple or brown in color.

Source: By James Heilman,MD - Own work, CC BY-SA 3.0

Usually around 10-14 days, multiple smaller patches appear on the body, which are characterized as smaller scaly patches.  These smaller patches typically occur on the chest, back, abdomen or lower extremities. In light skinned patients, the patches may look like the herald patch, except smaller.  Typically In darker skin patients, multiple raised, tiny bumps will appear. This scaly rash is often mistaken for tinea corporis (ringworm) or eczema,  as both of these conditions also appear as scaly erythematous patches on the body.

After the rash reaches its peak, where it does not spread anymore, it can last for several days or even months.  The skin rash of pityriasis rosea typically resolves after 8 to 10 weeks.

Atypical Pityriasis Rosea

Atypical Pityriasis Rosea may be diagnosed when the typical pattern and distribution is not typical to the general presentation of the rash.  There may be small papules, blisters, urticaria, purpura or larger confluent plaques.  The distribution may be “inverse” with more prominence of the rash in the axilla (armpits) and groin, arms and legs, rather than the trunk. These patients may never have a herald parch, and have instead, many larger patches or plaques. This atypical presentation of the skin rash can last for many months along with severe pruritus and recurrences of this eruption.

What are the Causes of Pityriasis Rosea?

The exact cause of pityriasis rosea remains a mystery. According to the American Academy of Dermatology (AAD), it is not an allergy, and it is not caused by bacteria or fungus. There is evidence, however, to suggest that the skin rash may be triggered by a viral infection, more specifically by the human herpes virus. There are many different strains of the human herpes viruses and the one that has been found to be linked to pityriasis rosea is HHV-6. This strain does not cause cold sores or genital herpes.

There is a possibility that patients develop pityriasis rosea when their immune system weakens.  This weak immune status allows the virus to spread and reproduce. However, more research is needed to understand the etiology of this skin rash.

Diagnosis of Pityriasis Rosea

Dermatologists are able to diagnose this skin disease with a thorough skin examination.  Typically the lesions presented are discrete circular or oval lesions.  There should be a  peripheral collarette of scaling with central clearance on more than two lesions.  Typically, there is a truncal and proximal limb distribution, with the lesions appearing along the skin cleavage lines. Many cases have the classic herald patch appearing before the other lesions occur. However, sometimes it can be difficult to diagnose pityriasis rosesa, as the eruption can resemble other skin disorders. Blood tests can be ordered and as well as a skin biopsy to determine the exact cause of the rash.  A fungus culture may be performed to rule out any fungal injection such as tinea corporis. A biopsy of the eruption involves taking a small skin sample under local anesthesia and sending it to the histologist to review under a microscope to determine the final diagnosis.

Treatment of Pityriasis Rosea

While the rash can go away on its own, typically within 8-10 weeks, there are several treatments which can help alleviate the symptoms.

Aveeno oatmeal baths are highly recommended to help patients who may experience itching. Avoid taking hot showers or hot baths as it can worsen the rash; use tepid water while bathing. Do not use exfoliating cleansers on your skin.  A gentle cleanser is recommended to bathe.

Over-the-counter medications can also help with symptoms of pityriasis rosea. This includes topical medications such as calamine lotion, topical steroid creams (hydrocortisone) or antihistamines (Benadryl or Zyrtec).

Exposing your skin to a conservative amount of sunlight can also help decrease the symptoms of the rash.  UVB Phototherapy may also help improve the rash and can be performed in a dermatologist’s office.  Light therapy can sometimes cause side effects such as discoloration in the treated area, even after the skin rash resolves.

For severe pruritus, Dr. Green may recommend a prescription steroid cream and antihistamines to relieve the itch.

In severe cases of Pityriasis Rosea, dermatologists, like Dr. Green may recommend taking prescription drugs such as oral steroids, or acyclovir.  Acyclovir is an antiviral medication which sometimes alleviates the herpes viruses. A seven day course of high dose acyclovir is the recommended treatment.

There are conflicting studies which have showed that oral erythromycin may or may not be effective in treating Pityriasis Rosea can due to its anti-inflammatory effect. Other studies have showed that azithromycin is ineffective at treating this skin rash.

Complications of Pityriasis Rosea

In most cases, Pityriasis Rosea not does cause any serious complications. However, if the skin rash lasts more than a few months, you should consult a board certified dermatologist, like Dr. Michele Green, to ensure that you have the correct diagnosis.

Studies have shown that pregnant women may have a higher risk of developing serious complications from Pityriasis Rosea. Studies have shows that women in the first trimester of pregnancy have an increased risk of miscarriages.  Other complications such as premature delivery and perinatal problems have been described in pregnant women as well.  If you are pregnant and develop a new rash, you should consult your gynecologist immediately.

If you’re concerned about a new rash or skin condition, please don’t hesitate to seek dermatological or medical advice. Contact us online today or call 212-535-3088. Dr. Michele S. Green, a board certified NYC dermatologist, will help determine the cause of your rash and the best medical treatment.

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