Introduction 

Keratosis pilaris (KP) is a condition that causes tiny bumps on the surface of the skin, mainly on the buttocks, arms, or cheeks.¹ Atopic dermatitis (AD), also commonly known as eczema, is a prevalent skin condition that leads to skin rashes, itchiness, and dry patches.² This article aims to dive into the relationship between KP and AD, and explore whether KP lies on the eczema spectrum and what this could mean for patients, including treatment approaches. In addition, we aim to discuss the symptoms and diagnosis of these conditions, as well as common similarities and differences between KP and AD.

What is keratosis pilaris? 

KP is a non-infectious disease that occurs when the hair follicles are blocked by a buildup of the protein keratin, which is found in the skin, hair, and nails, and is used to protect the skin from infection and harmful substances. KP causes tiny, rough, discoloured bumps on the surface of the skin. Common symptoms of KP include:³

• Dry and itchy skin, particularly in the areas of your arms, legs, or bottom
• A rough feel to the skin where the bumps occur 
• Worsening of the bumps in the winter months 

KP can affect people of all ages; however, it is more prevalent in babies, toddlers, children, and teenagers, and it may worsen around the stage of puberty. Many healthcare providers believe that KP is associated with genetic traits; hence, you are more likely to develop KP if a member of your family has KP too. 

Other factors that can increase the chance of developing KP include: having fair or lighter skin, asthma, diabetes, Down syndrome, and obesity. In addition, hypothyroidism (where the thyroid gland doesn’t make and release enough thyroid hormone into your bloodstream)⁴ and Cushing syndrome (caused by excess cortisol hormone in the body),⁵ may also raise the likelihood of developing KP. KP may eventually clear up on its own, with many patients experiencing this happening at ages 20-30, but it frequently persists for years and tends to come and go.⁶   

What is atopic dermatitis (eczema)?

Eczema is a non-infectious chronic skin condition that may be triggered due to the environment, including exposure to soaps, detergents, chemicals, allergens, and infectious agents. Other triggers include stress, heat, or changes in temperature and hormonal changes (i.e, in pregnancy). In addition, the tendency to have eczema often runs in families, similarly to KP. A genetic mutation essential for preserving a healthy skin barrier has been strongly associated with eczema development. This alteration makes the skin more vulnerable to infections and allows irritating substances and particles to penetrate the skin, triggering itching and inflammation. 

Symptoms of eczema include:

• Dry and itchy skin
• Redness of the skin 
• Flaking⁷ 

Eczema can affect people of all ages; however, it is more common in younger children. Atopic eczema can appear in different areas of the body; however, it mainly appears on the elbows, knees, and hands, and commonly on the face of babies. Flare-ups are when the symptoms of eczema worsen, and the skin becomes red and itchy. Eczema may affect the quality of life, such as worsening sleep schedules, damage to social and interpersonal interactions, and feelings of anxiety and frustration.⁸

Is there a link between keratosis pilaris and atopic dermatitis? 

KP is most commonly associated with AD, as both conditions are related to mutations in the filaggrin (FLG) gene. This gene encodes the blueprint for producing the protein profilaggrin, which is found in epidermal cells (the outer layer of the skin). Profilaggrin can be reduced to filaggrin. The role of filaggrin is to tightly compress together structural proteins in the epidermis, to compact and strengthen cells that form the barrier of the skin. In addition, the breakdown of filaggrin proteins creates molecules that control its pH to maintain the proper amounts of acidity and help the skin retain its natural moisture content, which results in a protective skin barrier.

20-30% of patients with AD have an FLG gene mutation compared to 8-10% of the general population without AD.⁹ A mutation in the FLG gene increases the risk of developing AD. A point to consider is that not all those with the FLG gene mutation will develop AD. AD is more likely to occur in patients with a mutation in both copies of the FLG gene than in those who only have one copy mutation. Patients with two mutant copies usually suffer from a more severe disease. AD development is linked to both FLG gene mutation and the amount of filaggrin proteins produced from each profilaggrin molecule.

Filaggrin deficiency can contribute to improper shedding of dead skin cells, causing keratin to accumulate around hair follicles, leading to the rough, bumpy texture characteristic of KP. Many individuals with KP may have coexisting skin sensitivities or dryness, reinforcing the connection between these conditions.

Differences and similarities between keratosis pilaris and eczema 

In many ways, KP and eczema are similar. Both conditions are non-infectious and have no current cure. In addition, both conditions tend to worsen as the air gets drier, for example, in the winter months. In terms of appearance, KP looks like small red bumps on the surface of the skin, whereas eczema tends to look dry and inflamed and often swollen. The bumps of KP are often red, brown, white, or skin-coloured, whereas eczema is pink or red. 

Patients with KP tend not to experience symptoms of itching, whereas those with eczema have itchy and painful patches as their main symptoms. The locations that KP commonly occurs on include the arms, thighs, and cheeks, and for eczema, this can be anywhere on the body; however, it is mainly found on the face and neck. 

A similarity is that both KP and eczema are related to the mutation of the FLG gene. Inflammation of the skin rarely occurs in patients with KP, but is more prevalent in patients with eczema. 

In terms of treatment, moisturising regularly and avoiding harsh products work well for both diseases. KP is triggered by dry skin, cold weather, and harsh skincare products, and eczema is triggered by allergens such as dust or pollen, irritants such as soaps, detergents, perfumes, dry weather, stress, and dietary factors where certain foods such as dairy or gluten lead to triggering of eczema in some individuals.¹⁰

Treatment approaches 

To treat the symptoms of KP, many measures can be taken at home by patients that include; moisturising the skin using a non-perfumed moisturiser, using mild and unperfumed soaps and bathing products, as well as gently scrubbing your skin with a washcloth or exfoliating glove to remove dead skin cells, and having cool or lukewarm showers and baths. To avoid worsening of KP symptoms, do not use perfumed soaps or bathing products on the skin, as these tend to dry out the skin, leading to the triggering of KP symptoms. Scratching, rubbing, and picking at the skin roughly will worsen the symptoms of KP, as well as avoiding hot showers as well as harsh scrubs.

For eczema, similar measures can be taken to avoid worsening of the symptoms, which include avoiding the triggers of eczema, such as harsh soaps and detergents. To avoid harsh soaps, an emollient with a pump dispenser can be used as a replacement for soap, and ensure the emollient is not shared with anyone. Regularly applying moisturising treatments on the skin (at least 2 times a day) can prevent the skin from drying up. Keeping the body cool and avoiding taking showers with hot water can prevent inflammation. Avoid using aqueous creams as these can worsen the symptoms of eczema, as well as avoiding scratching the eczema patches, as this can cause severe irritation. Cutting the nails short and using anti-scratch gloves on babies can prevent scratching of eczema.

Can treating one improve the other? 

Since both conditions involve damage to the skin barrier, treating one may sometimes help the other. Using gentle and fragrance-free moisturisers will help the symptoms of both KP and eczema, as dryness makes both conditions worse. As both are connected to gene mutations of the FLG gene, strengthening the skin barrier is key, and this can be done using creams and gentle cleansers to reduce irritation. Using eczema treatments such as antihistamines or steroid creams may reduce irritation and sensitivity to KP. Additionally, avoiding irritants and using gentle and simple skincare routines can prevent flare-ups in both KP and eczema. Finally, using gentle skin exfoliators may improve the overall health of the skin barrier. 

In short, treating KP will not “cure” eczema and vice versa, and where possible, individualised treatment is key, and the combination method may only work when both conditions coexist.

Summary

Atopic dermatitis and keratosis pilaris are two different but related skin disorders. Despite not being a kind of eczema, KP and eczema share genetic risk factors, especially mutations in the FLG gene. KP is more common in eczema sufferers, and both conditions can contribute to a more generalised atopic profile. By knowing this connection, we can assist people with both disorders to feel more at ease, improve early diagnosis, and direct more effective skin care practices. Both KP and eczema can be efficiently treated with tailored medications, avoidance of harsh chemicals found in soaps or detergents.