What is Piezogenic Pedal Papule?

In 1968, Shelley and Rawnsley first mentioned piezogenic pedal papules (PPP), which are small bumps that pop out from the inner side of each heel’s skin only while standing up or applying pressure to the foot sole. They used the term “piezogenic,” which means “pressure-producing,” but this term is not entirely accurate because these bumps appear due to pressure, not causing it.

Following this, reports introduced piezogenic wrist papules and muscle bulges on the lower legs, either alone or along with PPP. These bumps seem to be identical to the PPPs mentioned before. Because of the different types of these bumps, the term piezogenic papules has been used without specifying “pedal” (relating to foot).

There’s also a version that occurs in infants, which doesn’t involve the pressure component.

What Causes Piezogenic Pedal Papule?

Piezogenic papules, or skin-colored bumps that appear on the feet or wrists, aren’t usually seen as a condition that can be inherited. So far, there hasn’t been any link found between them and a specific connective tissue problem or condition.

However, there have been some reported associations with conditions like Ehlers-Danlos and Prader-Willi syndromes. These conditions involve weaknesses in collagen, a protein crucial for maintaining structure and strength in our bodies’ tissues, although the exact reason for the link hasn’t been proven yet.

There are several risk factors identified for piezogenic papules. However, we do not know the direct cause. People at risk include those who are overweight, those with pes planus (a condition where the arch of the foot has flattened), and people required to stand for long periods due to their job. Athletes, particularly those involved in activities like figure skating or long-distance running or high-impact sports, have been known to commonly develop these bumps.

Risk Factors and Frequency for Piezogenic Pedal Papule

Piezogenic papules are very common in the United States and around the world. These soothes typically don’t hurt, so they often go unnoticed and aren’t diagnosed. This means the actual number of people with these bumps is probably a lot higher than we know. Some studies have found them on up to 76% of people in the United States, often on their wrists. This is close to the results of another worldwide study. No one group of people is more likely to get them based on where they live, how much money they make, or what ethnic group they belong to. However, women get them more often than men.

Piezogenic papules often show up without any clear reason.
Some families report multiple cases across generations, which suggests it might be inherited.
However, no clear reason for this inheritance has been identified.
They can happen at any age, from babyhood to adulthood.
There’s a special type that shows up on non-walking babies and comes with bigger nodules on the side of the heel.
One study found these infantile papules on 6% of newborns and 39% of babies.

Signs and Symptoms of Piezogenic Pedal Papule

Piezogenic papules are small bumps that often don’t cause symptoms, but can sometimes be painful. It can be hard to identify these papules based only on a patient’s medical history, unless the patient is experiencing pain. If a patient has papules that hurt, doctors may ask about any intense activities, like heavy work or playing sports. Knowing about this condition can be really helpful for patients who haven’t been able to figure out why they’re in pain, especially if they haven’t noticed these small bumps.

Upon examination, piezogenic papules appear as firm, yellow or skin-colored bumps on the heel of the foot. They’re often found on the sides, back, or inside of the heel and tend to stick out more when the patient puts their full weight on their feet. Interestingly, these bumps usually go away when the patient is not standing or applying weight on the feet and typically occur on both feet. Similar bumps have been seen on the inside of the wrist when pressure is applied. Some patients will have bumps on both their feet and wrists. There have also been reports of patients with both foot and wrist bumps, as well as a muscle bulging in the lower legs.

In infants who aren’t yet walking, these bumps show up as larger nodules on the inside of the heel.

Testing for Piezogenic Pedal Papule

Usually, a simple physical check-up is enough for your doctor to diagnose you. However, they might ask you to put weight on the area where they suspect an issue. This helps them see small skin bumps, called papules, which can easily be missed. Sometimes, if your symptoms are unusual, and it’s not clear what’s causing your problems, your doctor might use a particular tool – an ultrasound – to double-check their diagnosis.

An ultrasound uses sound waves to create an image of your insides. These images can help your doctor see any changes or abnormalities in your tissues. An ultrasound is a straightforward and non-invasive way to confirm a diagnosis.

If there are still doubts about the diagnosis after an ultrasound, your doctor might decide to take a small sample of your tissue, called a biopsy, especially if they suspect another condition might be causing your symptoms.

In some circumstances, your doctor may refer you to a specialist for a second opinion. This could be an orthopedist, who specializes in the musculoskeletal system, or a podiatrist, who specializes in feet. They might also refer you to a cardiologist, a heart specialist, if they suspect that you might have mitral valve prolapse – a condition where one of your heart valves isn’t closing properly.

Treatment Options for Piezogenic Pedal Papule

Generally, no treatment is required. But if the issue is causing you pain, there are steps you can take to ease it. First, try changing some daily habits, such as losing weight, avoiding standing for long periods, and being careful not to injure your foot. If these strategies don’t work, you might consider using compression stockings, heel cups, and foot supports called orthotics.

If your pain persists despite these measures, your doctor could try more aggressive treatments. These might include injecting medication into the painful area, a process known as an intralesional injection. For some people with a genetic condition called Ehlers-Danlos syndrome, injections of a medication called betamethasone with a local anesthetic named bupivacaine have shown promise.

In severe cases, when the pain is unbearable and other treatments have not worked, surgery to remove the problematic area might be an option. There has been a recent case report suggesting that injections of deoxycholic acid, a compound that helps your body to break down fats, also could be potentially beneficial.

Piezogenic papules are a unique skin condition that can be easily diagnosed with just a physical exam. This is where doctors have the patient stand to check for little bumps on their feet, or apply pressure to the patient’s wrist to see if any appear there. Doing this will usually identify if the person has this condition or not.

There are actually quite a few names that have been used to describe the bumps that appear on a child’s foot due to this condition. Some of these include pre-calcaneal congenital fibrolipomatous hamartomas, bilateral congenital adipose plantar nodules, benign anteromedical plantar nodules of childhood, congenital piezogenic-like pedal papules, bilateral congenital fatty heel pads, and pedal papules of the newborn. While this can make the terminology a bit confusing, they are all really describing the same thing.

However, this condition must be differentiated from another similar condition named juvenile aponeurotic fibroma – which tends to present as a single, fixed and firm lump under the skin that often occurs in young children or teenagers. The latter is more frequently found on the wrists than the ankles. If the patient is suspected to have juvenile aponeurotic fibroma, an X-ray of the area can show clustered, speckled calcium deposits, which further help to confirm the diagnosis.

What to expect with Piezogenic Pedal Papule

The outlook for this condition is generally very good. Most people with this condition do not feel any pain, so it is mainly an issue of appearance. If someone does feel pain, doctors typically advise them to reduce their activity levels. Occupational and recreational therapy may also be recommended if needed.