What do the bumps look like?
| Clue | Keratosis pilaris | Folliculitis |
|---|---|---|
| Typical appearance | Tiny, rough, dry bumps. | Tiny bumps that can look white when filled with pus. |
| Common locations | Upper arms, thighs, cheeks, back and buttocks. | In children, often clothing covered areas such as the buttocks and thighs. |
| What is happening | Hair follicle openings contain keratin plugs. | Skin becomes irritated or infected. |
| Need for treatment | Harmless; treatment is optional for appearance. | In children, often clears when the trigger is avoided. |
A comparison table can help you describe the bumps, but it cannot examine them, despite its excellent alignment, a modest achievement for something with no eyes. Similar looking bumps can have different causes, so use these clues to explain what you notice rather than to make a diagnosis.1
Does redness or itching mean folliculitis?
No. KP can have redness around the hair follicles, and occasional itching can occur. Most people with KP otherwise have no symptoms. Redness does not automatically turn a rough follicular bump into an infection, and itching alone does not settle the diagnosis either.23
KP is characterised by plugs of keratin in follicle openings. Keratin is the material forming those plugs. Its exact cause remains unclear: abnormal plug formation is one explanation, while coiled hairs and inflammation around the follicle are also being investigated. A visible or trapped hair therefore does not settle whether a bump is KP or folliculitis.23
What should you do next?
Confirmed KP does not need treatment for health reasons. It is common in children and teenagers and can worsen during puberty. Teenagers and adults who want to change its appearance can discuss treatment with a dermatologist. For a child with folliculitis linked to tight clothing, avoiding that clothing can allow the bumps to clear on their own.1
KP treatment options include keratolytics, which help loosen the keratin buildup, retinoids and laser treatments. These are options for confirmed KP, not interchangeable treatments for every follicular rash. Complete smoothing is not a reliable expectation; satisfactory results can be difficult to achieve even with treatment. The choice starts with identifying the bumps, not selecting the strongest product, which is a less convenient order for a shopping cart.2
How does a dermatologist tell the difference?
A dermatologist can use dermoscopy to examine the bumps more closely. Dermoscopy is a close examination of the skin that does not require a skin sample. KP can show coiled or looped fine hairs, redness around follicles and material surrounding individual hairs. A skin biopsy can also confirm KP when needed.3
Even magnified features can overlap, which is a lot of ambiguity to fit into a close up. Pityrosporum folliculitis, a yeast related form, can show bumps and pustules with surrounding redness and scaling. It can also show coiled or looped hairs resembling those seen in KP. The whole pattern matters more than any single hair or red spot, which is why a close examination is more useful than choosing a diagnosis from one feature.3
KP and folliculitis are not the only possibilities. Small, smooth, dome shaped bumps on the central chest can be eruptive vellus hair cysts, rare cysts containing fine hairs. Their usual location and appearance help a clinician distinguish them. If the pattern does not fit either column, keep the diagnosis open rather than forcing the bumps into one of two categories.4
Where this answer comes from
- 1What are those bumps on my child's skin?aad.org
- 2Keratosis Pilaris Revisited: Is It More Than Just a Follicular Keratosis?pmc.ncbi.nlm.nih.gov
- 3Dermoscopy of Keratosis Pilarispmc.ncbi.nlm.nih.gov
- 4Eruptive vellus hair cystsdermnetnz.org
