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Petechiae vs. Keratosis Pilaris: What is the Difference?

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Petechiae and keratosis pilaris can appear as tiny red spots on the skin. However, petechiae appear as flat red spots while keratosis pilaris appear as raised bumps on the skin.

Keratosis pilaris are harmless and do not require treatment while petechiae can occur due to a variety of reasons which may require treatment.

This article reviews the differences between the two, their causes, and their treatment.   

What are they?

Petechiae are red or purple spots on the skin which appear due to bleeding into the skin. They can occur at any age, although they are commonly seen in old age and children.

Keratosis pilaris is a common skin condition that leads to bumps on the arms, legs, buttocks, or cheeks. It is usually seen in children, teenagers, and females (with hormonal changes). It is often seen in individuals with a family history of keratosis pilaris or a personal history of atopic dermatitis, allergies, dry skin conditions, obesity, or diabetes.

Difference in appearance

Difference in appearance of petechiae and keratosis pilaris.

What do petechiae look like?

Petechiae usually appears as red, reddish brown, or purple spots on the skin. They can appear in a cluster and may look like a rash.

Petechiae are flat, meaning if you touch them, you won’t feel them. In addition, they are not blanchable – if you press them the color does not fade. They can appear on the skin and the mucosal surfaces like the eyes or mouth.

What does keratosis pilaris look like?

Keratosis pilaris appears as raised bumps on the skin which can be skin-colored, red, purplish, brown, or black in color (depending on the person’s skin tone). If you touch them, you can feel them and they have rough surfaces so they can feel like sandpaper. Sometimes, you can see coiled hair in the bump of keratosis pilaris. 

Keratosis pilaris bumps usually appear like goosebumps. It can also resemble the plucked skin of chicken and that’s why it is called chicken skin.

In addition, keratosis pilaris usually appears symmetrically (like you will see them on both upper arms). Petechiae may involve multiple areas of the body, but they are not necessarily symmetrical.

Other Symptoms

Petechiae are not itchy, but a person may have other symptoms associated with the underlying medical condition. Like if petechiae occurs due to infection, one may have a fever, fatigue, swollen lymph nodes, etc.

Keratosis pilaris usually does not itch or hurt, although in some people it can cause itching.

Causes

Petechiae

Petechiae is not a medical condition but a sign of other medical conditions. It can be caused by harmless reasons like straining or minor injury or it can occur due to serious conditions like infections or cancer.

The causes of petechiae include decreased platelet count, autoimmune conditions, infections like meningococcemia, infective endocarditis, infectious mononucleosis, and viral hemorrhagic fevers like Dengue or yellow fever.

Petechiae can also occur due to drugs like antibiotics, anti-seizure medications, NSAIDs, or a few heart medications. Straining due to coughing, vomiting, or giving birth can also cause petechial spots, especially on the upper arms and neck. 

Keratosis pilaris

The exact reason behind keratosis pilaris is not known; however, it is thought to occur due to abnormal hyper-keratinization which results in blocking of the hair follicles with excess keratin. In addition, the structure of the hair shaft may play a role.

Diagnosis

Petechiae can occur due to various reasons so your doctor may do a physical examination and a few diagnostic tests to find the cause. This may be followed by additional testing if required

Keratosis pilaris can usually be diagnosed by a doctor after a physical examination.  

Treatment

Petechiae

Petechiae due to minor injury or after coughing or vomiting may go away on their own. However, petechiae that occur due to underlying medical conditions will require treatment.

The treatment will depend on the underlying cause.

  • If the cause is infectious, one may require antibiotics or antiviral medications. 
  • If the petechiae appeared due to a medication, your doctor may recommend stopping the drug or may prescribe another medication.
  • Autoimmune disorders may require the use of steroids or immunosuppressants.
  • Blood cancer/leukemia may require chemotherapy drugs, radiation therapy, or bone marrow transplant.
  • Petechiae due to vitamin C or K deficiency will require supplementation or dietary modifications.

Keratosis pilaris

Keratosis pilaris usually does not require treatment; however, if the appearance bothers you, it can be improved by the use of gentle skin care, moisturizers, urea-based products, exfoliants like salicylic acid, lactic acid, and glycolic acid, retinoids like retinol or tretinoin.

If the topicals fail, your doctor may recommend procedures like lasers, microdermabrasion, or chemical peels.

Keratosis pilaris is a chronic condition that cannot be cured so the Improvement lasts as long as the condition is treated. However, the condition may improve or disappear by the age of 30.

When to see a doctor

Both keratosis pilaris and petechiae can look alike. If you’re not sure that your skin lesions are petechiae or keratosis pilaris, you should see a doctor for evaluation.

Petechiae can be caused by serious medical conditions, so timely diagnosis and treatment are important.

In addition, you should see a doctor if:

  • You have a fever.
  • You feel sick.
  • You have other symptoms like fatigue, enlarged lymph nodes, bleeding from the mouth, or blood in urine and stool.
  • You feel dizzy or confused.

Note: Any child with fever and petechiae requires immediate medical care.

Key points

Petechiae and keratosis pilaris can appear as pinpoint red spots on the skin. However, petechiae are flat and do not fade when pressure is applied to them while keratosis pilaris are raised spots that feel rough.

Petechiae can appear anywhere on the body including mucous membranes like eyes and mouth. Keratosis pilaris is seen in areas with hair follicles and they’re often seen on upper arms, legs, buttocks, or cheeks.

Keratosis pilaris is a harmless skin condition whereas petechiae is a sign of other conditions, some of which can be serious like widespread or systemic infection and cancer. 

If you’re not sure whether you have petechiae or keratosis pilaris, it’s best to see your doctor. 

Further reading

References

Disclaimer: This blog post is for information purposes only and does not replace medical advice.

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