Papulosquamous Disorders

Papulosquamous disorders are a diverse group of skin conditions that have one thing in common: they are identified by red to purple, raised, scaly patches on the skin, with well-defined borders. Papulosquamous disorders have many different causes and treatments. Some of the most common include psoriasis, lichen planus, and certain drug eruptions.

What Are Papulosquamous Disorders?

Papulosquamous disorders are not just one skin disease. It's actually a term used to describe a group of unrelated skin conditions.

These disorders are not treated the same way; they don't even have the same root causes. Instead, these very different and diverse skin conditions are groups together solely by their appearance.

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.

It's not just any red, flaky rash, though. The defining characteristic of papulosquamous disorders is the sharp, distinct border of the lesions.

It may help to think of it this way: papulosquamous disorders aren't diseases in and of themselves. Instead, it is a description of a specific type of rash with a particular appearance. This rash can be caused by many different skin conditions.

Types of Papulosquamous Disorders

While papulosquamous disorders all have the same distinct look, each has a different cause and treatment depending on what is causing your rash.

Papulosquamous disorders can look incredibly similar to one another, which makes diagnosis tricky in some cases. Your doctor 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 doctor take a look at any rash that you develop so that you can get a correct diagnosis and learn how to effectively treat it.

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.

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 parapsoriasis 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, ringworm 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 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 skin condition 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 doctor in order to get a definitive diagnosis.

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