Sebaceous

Trichilemmal Cyst

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Trichilemmal Cyst, Scalp Cyst, Pilar Cyst, Wen, Proliferating Trichilemmal Tumor

  • See Also
  1. Epidermal Cyst
  2. Sebaceous Gland
  3. Common Benign Skin Growths
  • Epidemiology
  1. Most common in over age 15 years
  2. Family History predisposes to multiple Trichilemmal Cysts
  • Pathophysiology
  1. Intradermal cyst involving the scalp in 90% of cases
  2. Similar to Epidermoid Cysts
  3. Most common in areas of dense Hair Follicles
    1. Derives from outer Hair Follicle root sheath
  • Symptoms
  1. Asymptomatic in most cases
  2. No odor (unlike Epidermal Cysts)
  • Signs
  1. Well defined, scalp oval mass
  2. Scalp Cysts collect keratin of cheese consistency
  3. Multiple Scalp Cysts may coalesce
  4. May become inflamed if rupture occurs
  5. Often associated with overlying regions of Alopecia
  6. Most lesions are slow growing and benign (except Proliferating Trichilemmal Tumor)
  • Findings
  • Variants
  1. Proliferating Trichilemmal Tumor
    1. Rapidly growing lesions with overlying inflammation
    2. Complete surgical excision (risk of malignant transformation)
  • Differential Diagnosis
  1. Epidermoid Cyst
  2. Lipoma
  • Management
  • Excision
  1. Complete excision in standard fashion
  2. See Minimal Epidermal Cyst Excision
  • References
  1. Habif (1996) Clinical Dermatology, p. 644-5
  2. Wagner (2024) Am Fam Physician 110(4): 353-61 [PubMed]