Skin patches, or plaques, are common in psoriasis. They can also happen in other skin diseases, including parapsoriasis. Parapsoriasis isn’t a single condition. Instead, it’s an umbrella term for several skin diseases.

In Greek, “para” means “next to” or “alongside.” In medicine, “para” indicates a condition that’s like another. Here’s how to tell these two conditions apart.

Is Parapsoriasis the Same as Psoriasis?

Parapsoriasis isn’t the same as psoriasis. It’s a different condition. The main difference between parapsoriasis and psoriasis is that parapsoriasis plaques tend to be thinner. The cause of parapsoriasis is unknown, but — just like psoriasis — parapsoriasis is not contagious.

Parapsoriasis is a rare disease. It isn’t usually itchy like psoriasis. There’s a very small chance that it can increase the risk of skin cancer. People with psoriasis or parapsoriasis should make sure to get regular skin cancer screenings.

Types and Symptoms of Parapsoriasis

There are two main types of parapsoriasis: small plaque parapsoriasis (SPP) and large plaque parapsoriasis (LPP). They look different and come with different risks.

Small Plaque Parapsoriasis

People with SPP develop round or oval spots that are around 2 inches, or 5 centimeters, in diameter. They’re pink, yellowish, or brown with small scales. SPP typically affects the trunk (meaning the back and abdomen) but can also spread to the upper arms and thighs. Usually, the patches don’t get worse over time. It’s very rare for SPP to turn into cancer.

Digitate dermatosis is a specific type of SPP. The spots can be longer than 2 inches and are shaped like fingers. They also have a slightly rough texture. Digitate dermatosis affects the sides of the body between the ribs and the hips.

Large Plaque Parapsoriasis

The skin patches in LPP are bigger and have an irregular shape. They’re also darker and may look dusky red or brown. LPP tends to show up in places that don’t usually get much sun, like the buttocks, thighs, breasts, and lower back and belly.

LPP may progress into mycosis fungoides. This is a rare form of skin cancer that affects white blood cells, known as T cells. Mycosis fungoides is a type of cutaneous T-cell lymphoma (CTCL).

Normally, T cells help the immune system. But in CTCL, they grow abnormally in the skin and may eventually spread to other areas of the body. According to researchers, 10 percent of people with LPP develop mycosis fungoides. Some scientists believe that LPP is simply an early stage (also referred to as the patch stage) of CTCL.

Parapsoriasis Diagnosis

Your dermatologist will start by doing a physical exam to see if you might have parapsoriasis. They may also do a biopsy and genetic and molecular testing to rule out CTCL. A punch biopsy removes a small, deep piece of skin for testing under a microscope. It lets the dermatologist view all layers of the affected skin. Your dermatologist may need to take biopsies from multiple areas of your body. They may also want to repeat the test periodically to monitor for changes.

Part of getting the right diagnosis will include differential diagnosis. This involves your doctor considering other health conditions that may also explain your symptoms.

Parapsoriasis Treatment

Treatment for parapsoriasis varies based on the specific diagnosis. SPP may not require medical treatment because it’s benign (noncancerous) and may go away on its own. Generally, managing SPP focuses on relieving symptoms. Your doctor may recommend that you use topical corticosteroids, moisturizers, or phototherapy.

Follow-up appointments are recommended yearly for people living with SPP, but your doctor may follow a different schedule. Certain changes to the skin may prompt your doctor to biopsy the skin to check for cancer.

LPP often requires more aggressive therapy to prevent it from progressing. Treatments for LPP include:

• Topical treatments, including corticosteroids
• Psoralen plus ultraviolet (UV) A phototherapy
• UVA or UVB phototherapy

It’s important to keep up with your follow-up visits, even if you feel like your skin condition is under control. Monitoring for signs of cancer or other issues can help you catch problems early and get proper treatment. You should also let your healthcare provider know if you develop new symptoms, like larger plaques or spots in new areas.

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