Epidermoid and pilar cysts (sebaceous cysts)

Question 1

Define Epidermoid cysts

Answer 1

intradermal or SC cyst that originate in the dermis

Question 2

Define Pilar cysts

Answer 2

originate from hair follicles (90% occur on scalp)

Question 3

Aetiology of Epidermoid and pilar cysts

Answer 3

The cyst lining is either normal epidermis (epidermoid cyst) or outer root sheath of hair follicle (pilar cyst)
Blocked sebaceous gland
Swollen hair follicle
Raised testosterone
Use of androgenic anabolic steroids
Genetic: Gardner’s syndrome, basal cell nevus syndrome

Pilar cysts often have an autosomal dominant inheritance

Question 4

Risk factors for Epidermoid and pilar cysts

Answer 4

After puberty 
History of acne 
Genetics
Skin injury 
Female (middle age)

Question 5

Symptoms of Epidermoid and pilar cysts

Answer 5

Mobile mass

• Affect face and trunk (anywhere except hands and soles of feet)
• Smooth
• Round
• Vary in size
• They have a central punctum

Question 6

Signs of Epidermoid and pilar cysts

Answer 6

Painless mobile lump

• Affect face and trunk (anywhere except hands and soles of feet)
• Pilar cysts are most common on the scalp, where several can often be found
• Epidermoid cysts are most common on the face, neck, genital skin and upper trunk

Smooth | round | vary in size | central punctum

Infection: red, inflamed, painful

Question 7

What may be contained in the central punctum of epidermoid and pilar cysts (sebaceous cysts)

Answer 7

They may contain small quantities of sebum or: Fibrous tissues and fluids Fatty (keratinous) substance - “cheesy” or foot odour smell
Viscous, serosanguineous fluid (contains purulent, bloody material)