Pilar sheath acanthoma

Pilar sheath acanthoma is a rare benign skin lesion.

Pilar sheath acanthoma
Diagnosis in short
Template:Px Pilar sheath acanthoma. H&E stain.
LM DDx	trichofolliculoma, dilated pore of Winer, epidermal inclusion cyst
Gross	raised lesion, central cavitation
Site	skin - classically upper lip
Clinical history	typically middle aged - 50s
Prevalence	rare
Prognosis	benign

General

• Rare.
• Considered a hamartoma.
• Does not regress like keratoacanthoma.
• Typically middle aged individuals - median age in one series 55 years old, range 46-75 years old.

Gross

• Raised lesion with a central depression - somewhat similar to keratoacanthoma.
• Classcially upper lip.

DDx:

• Keratoacanthoma.

Microscopic

Features:

• Cystic cavity with:
  • Keratineous material.
  • Usually extends from surface to deep cutis - like a hair shaft.
  • Lining consists of a thickened squamous epithelium.

DDx:

• Trichofolliculoma.
• Dilated pore of Winer.
• Epidermal inclusion cyst.

Images

• 

  PSA. (WC)

www:

• Pilar sheath acanthoma (dermnet.org.nz).

See also

• Dermatopathology.
• Skin cysts.