What Are Papulosquamous Disorders?

Papulosquamous disorders are a diverse group of unrelated skin conditions. These disorders are only categorized together for one reason: They all cause red to purple, raised patches of scales on the skin that have well-defined borders.

Some of the most common papulosquamous disorders include psoriasis, lichen planus, and medication reactions. These and other skin issues that fall under this umbrella not only have different root causes, but different treatments, too.

Recognizing Papulosquamous Scales

Papulosquamous skin disorders cause papules (red, raised bumps) and plaques (a flat, thickened area of skin) that are flaky or scaly. These patches may or may not itch.

The defining characteristic of papulosquamous disorders, however, is the sharp, distinct border of these lesions.

Papulosquamous lesions can look incredibly similar to one another, which makes diagnosis tricky in some cases. Your healthcare provider will determine what is causing your rash by examining your skin and taking a thorough medical history.

Other tests, such as a skin biopsy, blood tests, or skin scrapings, may also be needed to pinpoint the cause.

It is important to have your healthcare provider take a look at any rash that you develop so that you can get a correct diagnosis and learn how to effectively treat it.

Types of Papulosquamous Disorders

While papulosquamous disorders all have the same distinct look, each has a different cause and treatment.

Examples of papulosquamous disorders include:

• Psoriasis
• Seborrheic dermatitis
• Lichen planus
• Parapsoriasis
  
• Drug eruptions (reactions)
• Pityriasis rosea
• Secondary syphilis
• Tinea corporis (ringworm)
• Discoid lupus
• Nummular eczema

Psoriasis

Psoriasis is probably the most well-known papulosquamous disorder. It is also the most common. Psoriasis is an autoimmune disorder that causes skin cells to build up at an abnormal rate. Plaque psoriasis is the most common, but there are many different types of psoriasis.

This skin condition is chronic, and it can't be cured. It can be managed, however, with the right medications and self-care.

Seborrheic Dermatitis

Seborrheic dermatitis is a chronic inflammatory skin condition that commonly affects the scalp. It can cause red and greasy patches or scales on the skin, along with yellowish scales and dandruff.

The exact cause of this condition is unknown. Experts believe that an overgrowth of a type of yeast that lives on the skin known as Malassezia is a probable cause.

This papulosquamous disorder is typically treated with over-the-counter (OTC) shampoos and creams. A healthcare provider may prescribe antifungal creams and shampoos or a topical corticosteroid for more severe cases.

Lichen Planus

Lichen planus causes purplish, flat, itchy lesions. The rash can appear anywhere on the body, including inside the mouth. It is also caused by an autoimmune response but, unlike psoriasis, lichen planus can go away over time.

Until it does, it is often treated with topical corticosteroids to help relieve itching. Licen planus is not contagious.

Parapsoriasis

Though the name sounds similar to psoriasis, parapsoriasis is a different condition, mostly affecting adult males.

Like psoriasis, parapsoriasis is also marked by pink, scaly patches on the skin ranging from 1 cm to 5 cm in diameter, however, the plaques in parapsoriasis are often asymptomatic.

There are two types of parapsoriasis: small plaque parapsoriasis (SPP) and large plaque parapsoriasis (LPP), with LPP being considered a premalignant dermatosis (potentially cancerous).

Diagnosis of this papulosquamous disorder can be difficult, but usually requires a skin biopsy. Treatment may include corticosteroids and phototherapy.

Drug Eruptions

Skin rashes can also be caused when you have a reaction to a medication. Drug eruptions usually appear within the first two weeks of starting a new medication. These rashes are typically very itchy.

Pityriasis Rosea

For being a fairly common skin condition, not much is known about what causes pityriasis rosea. It seems to be triggered by a viral infection.

What makes this particular papulosquamous disorder unique is the appearance of a herald patch⁠—a circular to oval spot that typically appears on the trunk. A widespread rash develops after that.

Pityriasis rosea does go away on its own, generally within two months. Anti-itch creams or hydrocortisone can help relieve itching until it's gone.

Secondary Syphilis

Syphilis is a sexually-transmitted infection (STI) caused by the Treponema pallidum bacterium. It can cause a widespread skin rash during its second stage of infection, which occurs approximately four to 10 weeks after initial infection.

Syphilis can be cured with antibiotics.

Tinea Corporis (Ringworm)

The rash produced by tinea corporis, better known as ringworm, is fairly distinct and so is generally easy to diagnose. Despite the name, this papulosquamous disorder is caused by a fungus and not a worm.

Ringworm is easily treated with topical antifungal medication. Unfortunately, it is also very contagious and is easily spread by skin-to-skin contact.

Discoid Lupus

Discoid lupus is a form of lupus that primarily affects your skin. It is an autoimmune disease that causes the immune system to attack your skin.

With discoid lupus, a chronic, widespread, inflammatory rash is common. It can be effectively treated although not cured.

Treatments for this papulosquamous disorder include topical corticosteroids, and topical calcineurin inhibitors (pimecrolimus cream or tacrolimus ointment).

Nummular Eczema

Nummular eczema, also called discoid eczema, is a specific type of eczema that causes round, coin-shaped lesions. Unlike common eczema, the lesions of nummular eczema are very distinct.

This papulosquamous disorder is extremely itchy. Topical medications can help get the rash under control, but once you've had it, you're more likely to experience another breakout.

A Word From Verywell

Papulosquamous disorders are diverse and distinct. Because they can resemble one another, it's important that you see your healthcare provider in order to get a definitive diagnosis.

Once your skin condition is identified, your healthcare provider can help you create an effective treatment plan to help manage your specific skin condition.