What is a pilar cyst?
A hair follicle is the skin structure that produces a hair. A pilar cyst is related to its outer root sheath: a cell-lined cavity forms and collects keratin. Keratin is a protein found in skin and hair, not pus or a pocket of fat that a cosmetic product can dissolve.
The lesion usually grows slowly and may remain painless for a long time. The popular name “sebaceous cyst” is imprecise: an epidermoid cyst and a pilar cyst have different origins and features. A pilar cyst usually lacks the small visible central opening that may be present in an epidermoid cyst. No single feature replaces examination.
[1]
Why can several family members have scalp lumps?
Some people have multiple cysts and relatives with similar lesions. A genetic study published in 2020 identified changes in PLCD1 in a hereditary form of trichilemmal cysts. This helps explain predisposition, but does not make every scalp lump a genetic disorder or mean everyone needs testing.
Tell the clinician whether parents, siblings or other relatives have had lumps removed and bring pathology reports when available. This history is more useful than repeatedly changing shampoos to discover a cause. A cyst should not automatically be attributed to poor hygiene.
[2] [1]How assessment distinguishes a cyst from other lesions
Examination considers location, size, mobility, firmness, the overlying skin and growth rate. The clinician also asks about inflammation, previous operations, medicines, other conditions and discomfort when brushing hair, sleeping or wearing accessories.
Not every scalp lump is a pilar cyst. Other cysts, lipomas, inflammatory lesions and skin tumors may be considered. Ultrasound, biopsy or referral depends on examination findings; there is no mandatory test package for everyone. When a lesion is removed, examination of the tissue may confirm its nature and guide follow-up.
[1] [4]When delaying assessment can cause problems
A confirmed, stable and symptom-free cyst may be monitored. This differs from leaving an undiagnosed lump to grow indefinitely. Increasing size can make brushing uncomfortable, cause pressure while lying down and lead to repeated trauma. Inflammation or rupture can be painful and make capsule removal more difficult.
Rapid growth, a persistent sore, spontaneous bleeding or recurrence with a different appearance after surgery requires investigation. Proliferating pilar tumors are uncommon and need their own assessment. Studies of those tumors cannot determine the transformation risk of an ordinary cyst or support claiming that every cyst becomes cancer.
[1] [4]When to bring assessment forward
Seek same-day care for significant pain, spreading redness, discharge with worsening symptoms or fever. If you become seriously unwell, seek urgent medical care. Do not wait for a clinic form or social-media response during an acute problem.
A rapidly growing lump or one that changes appearance deserves prompt assessment even without fever. Stable lesions can be assessed at a planned appointment. Urgency depends on symptoms and examination, not simply the word “cyst”.
[5] [4]Monitoring or removal: how the decision is made
The plan considers diagnostic certainty, symptoms, size, previous flares, preferences and procedural risks. Removal may be discussed for pain, recurrent discomfort, growth or uncertainty about the lump. A well-characterized, symptom-free lesion does not necessarily require immediate surgery.
When removal is indicated, the usual aim is to remove the lesion and its capsule. Emptying its contents is not the same as removing the structure that produces them. Technique, anesthesia and wound closure depend on location and in-person assessment. Neither a scar-free result nor zero recurrence can be promised.
During a flare, inflammation and infection must be distinguished. Rupture can cause an inflammatory reaction without bacteria being the primary cause. Do not start or repeat antibiotics yourself. Sometimes the acute episode is managed before definitive removal.
[1] [3]What to discuss before and after a procedure
Report allergies, current treatment, healing problems and previous bleeding. Do not stop anticoagulants or other medicines without guidance from the responsible team. Ask whether stitches need removal, when hair washing is appropriate and which activities need adjustment.
The treated area may be tender and surgery leaves a scar whose appearance varies. Bleeding, wound infection, wound separation and recurrence are risks to discuss. The relationship between the incision and hair follicles also matters in planning. Follow-up assesses healing and explains pathology results when tissue has been examined.
[6] [3]Do not puncture or drain it yourself
Needles, blades, forceful pressure and corrosive products can injure the scalp and introduce infection. Household remedies, borrowed creams and products claiming to dissolve lumps do not replace diagnosis and can make the lesion harder to assess.
If the lesion opens spontaneously, do not probe it or try to pull out its capsule. Seek guidance so the site can be assessed. Prescribed home care, including cleansing or dressings when appropriate, is part of medical follow-up and should follow individual instructions.
[5] [6]What the studies show, and their limits
The PLCD1 study investigated inheritance mechanisms rather than comparing treatments. Research on small-incision removal included keratinous and pilar cysts and used retrospective records and a follow-up survey; it does not establish one technique for every patient.
The proliferating-tumor series studied lesions selected for their pathological features. Its findings should not be transferred to a typical small pilar cyst. Clinical decisions combine history, examination, the nature of the lesion and the quality of evidence.
[2] [3] [4]10 ANSWERS TO COMMON QUESTIONS
Frequently asked questions
Are pilar cysts and sebaceous cysts the same?
“Sebaceous” is a popular name often applied to different lesions. A pilar cyst is related to the hair follicle; an epidermoid cyst is another type. Examination helps determine the most likely diagnosis.
Is every scalp lump a pilar cyst?
No. Other lesions can look similar. Growth, mobility, surface changes and symptoms need assessment; a photograph alone cannot establish the diagnosis.
Must a painless cyst be removed?
Not necessarily. After assessment, a stable and well-characterized lesion may be monitored. Symptoms, growth, diagnostic uncertainty and informed preference influence the decision.
Can a person have several cysts?
Yes. Multiple lesions and a family history can occur. Mention this at the appointment, without assuming everyone needs genetic testing.
Can shampoo or cream make it disappear?
These products should not be chosen to eliminate a capsule beneath the skin. A suitable product for a scalp condition does not replace assessment of the lump.
Does a red cyst always need antibiotics?
No. Rupture and inflammation can occur without bacterial infection. The team assesses symptoms, extent and general health before selecting treatment.
Can surgery leave a scar?
Yes. Planning balances adequate removal and tissue preservation, but no operation guarantees no mark. Discuss wound care, stitches and follow-up.
Can the cyst return?
Recurrence is possible, especially if part of the wall remains. Another cyst may also develop in a predisposed person. A new lump warrants reassessment.
Does rapid growth mean cancer?
It does not establish cancer, but requires prompt assessment. Inflammation, other diagnoses and proliferating lesions need to be distinguished. Do not wait simply because someone called the lump a cyst.
What should I bring to the appointment?
A medicine list, dated photographs, details of growth and flares, and previous pathology reports. Describe discomfort during sleep or hair brushing and similar lesions in relatives.
Guides for further reading
Also see: lipomas · skin biopsy · boils.
Bibliography and published research
References in Vancouver/NLM style; accessed September 21, 2026. Journal articles and institutional guidance are identified in each entry.
- Kapadia A. Trichilemmal cyst [Internet]. [place unknown]: DermNet; 2014 [cited 2026 Sep 21]. Available from: https://dermnetnz.org/topics/trichilemmal-cyst.
- Kolodney MS, Coman GC, Smolkin MB, Hagen R, Katzman JA, Katzman SN, et al. Hereditary Trichilemmal Cysts are Caused by Two Hits to the Same Copy of the Phospholipase C Delta 1 Gene (PLCD1). Scientific Reports. 2020;10(1):6035. doi: 10.1038/s41598-020-62959-z. Available from: https://pubmed.ncbi.nlm.nih.gov/32265483/ [cited 2026 Sep 21].
- Mehrabi D, Leonhardt JM, Brodell RT. Removal of keratinous and pilar cysts with the punch incision technique: analysis of surgical outcomes. Dermatologic Surgery. 2002;28(8):673–677. doi: 10.1046/j.1524-4725.2002.02020.x. Available from: https://pubmed.ncbi.nlm.nih.gov/12174056/ [cited 2026 Sep 21].
- Ye J, Nappi O, Swanson PE, Patterson JW, Wick MR. Proliferating pilar tumors: a clinicopathologic study of 76 cases with a proposal for definition of benign and malignant variants. American Journal of Clinical Pathology. 2004;122(4):566–574. doi: 10.1309/0XLEGFQ64XYJU4G6. Available from: https://pubmed.ncbi.nlm.nih.gov/15487455/ [cited 2026 Sep 21].
- National Health Service. Skin cyst [Internet]. London: NHS; 2023 [cited 2026 Sep 21]. Available from: https://www.nhs.uk/conditions/skin-cyst/.
- Ludmann PL. Skin biopsy: Dermatologist-recommended wound care [Internet]. Rosemont: American Academy of Dermatology; [date unknown] [cited 2026 Sep 21]. Available from: https://www.aad.org/public/diseases/a-z/skin-biopsy-wound-care.