II. Epidemiology
- Most common skin cyst
III. Causes
- Ruptured Pilosebaceous Follicle (acne comedone)
- Local Trauma buries surface epithelium under skin
IV. Pathophysiology
- Previously known as Sebaceous Cysts but not derived from sebaceous tissue
- Common Locations
- Head and Neck
- Face
- Ears
- Chest
- Back
- Lesion
- Implanted epidermal elements into deeper dermal layers
- Cyst wall: stratified squamous epithelium
- Central punctum is typically present on close exam (hallmark finding of Sebaceous Cyst)
- Cyst contents
- Does not contain Sebaceous Glands
- Keratin and lipid
- Breakdown products
- Bacterial Infection
-
Cyst rupture effect (keratin spills into Dermis)
- Significant inflammation
- Lesion may scar or become infected
V. Symptoms
- Usually asymptomatic
- Soft, yellow keratin discharge may have foul odor
VI. Signs
- Round, mobile, smooth surfaced, discrete Nodule
- Slow growing lesion from 5 mm to 5 cm in diameter
- Visible pore may be present at center of lesions
- May be inflamed if cyst has ruptured
VII. Differential Diagnosis
- See Soft Tissue Mass
- See site specific (e.g. Neck Masses in Children)
- Lipoma
-
Milia (1-2 mm lesion)
- Puncture with needle, express with comedone extractor
- Dermoid cyst
- May extend intracranially (CT Head before excision)
- Locations
- Follow Cleavage Lines
- Sublingual
- Periorbital
- Base of nose
- Gardner's Syndrome
- Autosomal Dominant condition associated with Colonic Polyps and Colon Cancer
- Children with Sebaceous Cysts
- Adults with Sebaceous Cysts in rare location (fingers, toes)
- Multiple Lipomas, fibromas, osteomas
VIII. Types: Variations with multiple lesions
- Steatocystoma Multiplex
- Numerous 2-3mm lesions on trunk, arm, axilla, thigh
- Favre-Racouchot Syndrome
- Multiple facial lesions due to sun damage
IX. Management
- Non-inflamed cyst
- Small to moderate sized cysts
- Large Cysts (2 cm or larger)
- Complete excision in standard fashion
- Remove cyst intact via Blunt Dissection
- Inflamed or infected cyst
- Warm compresses
- Incision and Drainage
XI. References
- Habif (1996) Clinical Dermatology, p. 644
- White (1994) Regional Dermatology, p. 27
- Higgins (2015) Am Fam Physician 92(7): 601-7 [PubMed]
- Zuber (2002) Am Fam Physician 65(7):1409-12 [PubMed]