Prurigo nodularis (PN), also known as nodular prurigo, is a skin disease that causes inflamed bumps on the skin. These bumps — called papules or nodules, depending on their size — usually appear on the arms, legs, back, belly, and chest. “Prurigo” refers to itching, and doctors may describe the intense itching associated with the condition as pruritus or refer to pruritic nodules. PN symptoms appear differently from person to person, depending on factors like skin tone, location on the body, coexisting skin conditions, and the severity of the condition.

This article shows some of the ways PN may appear. However, many of the available dermatology images lack diverse skin tones. Two people with PN are unlikely to have skin symptoms that look alike. If you believe you may have PN, see a dermatologist to be diagnosed and receive appropriate care.

Read on for photos and descriptions of how PN symptoms can appear.

Size of Nodules

PN lesions may vary in size from just a few millimeters to over an inch wide. Different sized lesions have different names. Smaller lesions, also known as papules, are raised bumps less than 1 centimeter wide (or smaller than 0.4 inch). These often feel firm and appear less severe.

Larger lesions, also known as nodules, are greater than 1 centimeter wide. Lesions can change in size over time — a papule may grow to become a nodule, and a nodule may shrink to the size of a papule. Larger nodules may be more likely to break open when scratched and may form open wounds. These may be erosions, which are shallow sores, or ulcerations, which are deeper with more extensive skin loss.

Color and Skin Tone

PN lesions may appear in a variety of colors. They may be more pale or darker than your normal skin tone, or they may be tinted red, pink, brown, or black. You also may have varying colors of nodules on different parts of your body. For example, one nodule on your arm could be purple while another on your leg could be blue.

Inflamed or irritated nodules may look red or pink on light skin and purple, blue, brown, or black on darker skin. If you can see bright red blood, your lesion may have become ulcerated. White or yellow fluid could be pus due to a bacterial infection.

Number and Grouping of Nodules

Skin nodules may be grouped together to form a cluster called a plaque. Lesions may also be spread out and isolated from one another. You may have a few nodules on your entire body at a given time or hundreds spread across your trunk and limbs.

Location

Prurigo nodularis symptoms can appear at any location in your body, but they’re most likely to appear in spots that are easier to scratch or pick at. These include arms and legs, lower back, stomach, chest, buttocks, and scalp. Nodules are less likely to be found in the middle of the back or other places that are difficult to scratch. In extensive cases, PN lesions may spread across multiple body parts.

Nodule Shape and Feel

PN nodules may feel hard and bumpy, like a dome on your skin’s surface. Dome-shaped skin lesions due to PN may have an indent in the center, which doctors describe as “pitted.” Lesions are more likely to become pitted if they are scratched or irritated.

The shape and structure of each nodule may depend on how long it has been there, how much it has been scratched, the thickness of the skin around it, and many other factors.

Skin Infection

When nodules become infected, they may change in appearance. Scratching can tear up and wear away skin over the nodule (changes doctors refer to as “excoriations”), increasing the likelihood of infection. Bacteria from your hands or the surrounding skin get into an open nodule and spread.

The infecting bacteria can trigger your immune system to increase the flow of blood with important immune cells to the area. This is why an infected nodule may be warm and tender to the touch, turn red from increased blood flow to the area, or leak white or yellow pus or other fluid. During the healing process, the nodule may form a scab that’s hard and crusted over.

Scarring

After a large or especially irritated nodule breaks open, scabs, and begins to heal, it might leave behind a scar, or the area may become lighter or darker than the normal skin. A scar forms when new tissue, made from a protein called collagen, grows over an open wound. For a long time after the wound closes up, the skin can appear discolored or raised, even though the original nodule is gone.

Other Skin Conditions With Similar Symptoms

Several other inflammatory skin conditions have symptoms that resemble the lesions seen in PN. It’s also possible to simultaneously have PN and another skin condition.

A few skin conditions that may be confused with or related to PN include:

• Atopic dermatitis (often referred to as eczema)
• Psoriasis
• Lichen simplex chronicus
• Skin changes due to liver disease, lymphoma, or thyroid conditions
• Skin cancers

Diagnosis and Treatment

Only a dermatologist experienced in diagnosing prurigo nodularis can determine what’s causing your lesions. A doctor may need to conduct a skin biopsy to be certain. This entails removing a small sample of skin to view under a microscope. Once a doctor diagnoses your condition, they can prescribe treatments such as corticosteroids, immunosuppressants (which may be topical, taken orally, or injected), or phototherapy. Effective treatment of prurigo nodularis can help improve your quality of life by reducing the itching and clearing the skin lesions

Talk With Others Who Understand

Living with prurigo nodularis can be challenging, but you don’t have to go through it alone. When you join MyPrurigoTeam, you’ll gain a community of people who understand what it’s like to live with PN.

What does your PN look like? Do track your skin changes over time? Share your thoughts in the comments below or by posting on your Activities page.