SynopsisCodesLook ForDiagnostic PearlsDifferential Diagnosis & PitfallsBest TestsManagement PearlsTherapyReferences

Information for Patients

View all Images (25)

Pilar cyst
See also in: Hair and Scalp
Other Resources UpToDate PubMed

Pilar cyst

See also in: Hair and Scalp
Contributors: Amy Kalowitz Bieber MD, Susan Burgin MD
Other Resources UpToDate PubMed


Pilar (trichilemmal) cysts, sometimes referred to as wens, are common, benign cysts of hair follicle origin that are most often found on the scalp. They are derived from the outer root sheath of the hair follicle. Histologically, they are lined with multilayered epithelium that does not mature through a granular layer.

The cysts are smooth and mobile, are keratin filled, and may or may not be tender. They occur most commonly in middle-aged individuals, especially women. They may be present as solitary or multiple lesions. Pilar cysts are the most common type of cutaneous cyst of the scalp and the second most common cutaneous cyst of the head and neck (after epidermal inclusion cysts).

Rarely, these cysts form proliferating pilar tumors (more commonly called proliferating trichilemmal cysts), which are benign but may be locally aggressive or ulcerate. Malignant transformation is very rare but can lead to distant metastasis. Verrucous pilar cysts, or pilar cysts with features of human papillomavirus infection on histopathology, have also been described.

Pilar cysts may be inherited as an autosomal dominant trait with incomplete penetrance. Multiple cysts may develop in these cases. A variant of the PLCD1 gene has been shown to be associated with cyst formation in these families, and recent genetic studies suggest that a somatic mutation on the same allele (a monoallelic two-hit mechanism) is the genetic trigger for cyst development.


L72.11 – Pilar cyst

254677004 – Trichilemmal cyst

Look For

Subscription Required

Diagnostic Pearls

Subscription Required

Differential Diagnosis & Pitfalls

  • Epidermoid cyst (epidermal inclusion)
  • Cutaneous dermoid cyst
  • Proliferating pilar tumor
  • Malignant proliferating trichilemmal tumor
  • Osteoma cutis
  • Pilomatricoma
  • Lipoma
  • Solitary neurofibroma
  • Pseudolymphoma (lymphocytoma)
  • Acne keloidalis nuchae
  • Favre-Racouchot syndrome
  • Furunculosis (if cyst is ruptured)

Best Tests

Subscription Required

Management Pearls

Subscription Required


Subscription Required


Subscription Required

Last Reviewed:12/12/2019
Last Updated:01/20/2022
Copyright © 2024 VisualDx®. All rights reserved.
Patient Information for Pilar cyst
Print E-Mail Images (25)
Contributors: Medical staff writer
Premium Feature
VisualDx Patient Handouts
Available in the Elite package
  • Improve treatment compliance
  • Reduce after-hours questions
  • Increase patient engagement and satisfaction
  • Written in clear, easy-to-understand language. No confusing jargon.
  • Available in English and Spanish
  • Print out or email directly to your patient
Copyright © 2024 VisualDx®. All rights reserved.
Pilar cyst
See also in: Hair and Scalp
A medical illustration showing key findings of Pilar cyst : Scalp
Clinical image of Pilar cyst - imageId=80847. Click to open in gallery.  caption: 'A yellowish nodule with overlying diminished hair growth on the scalp.'
A yellowish nodule with overlying diminished hair growth on the scalp.
Copyright © 2024 VisualDx®. All rights reserved.