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SEBACIOUS CYST

Introduction

Sebaceous glands are simple or branched alveolar organs in the skin, especially where hair is concentrated (eg, sebaceous glands are absent from the palms). The duct for each gland usually opens into the sheath of a hair follicle, although it may open directly on the surface of the skin. A sebaceous cyst is a closed sac under the skin that presents as a small lump. It forms when the sebaceous gland’s secretions accumulate and occlude the duct and can occur at any age. It is usually painless, but may become inflamed and tender. While most sebaceous cysts are benign, if they become infected, necrotizing fasciitis may ensue, but it is rare. About 3% of sebaceous cysts become malignant.  There are multiple synonymous terms used to identify the sebaceous cyst. Other names included epidermal inclusion cyst, wen, steatoma and epidermoid cyst.  Some authors identify the sebaceous cyst as a separate and distinct lesion because its cells secret sebcum into the cyst while the invaginated epidermis of the epidermoid cyst fills the lesion with layers of keratin.  Clinically the epidermoid cyst is typically a firm (almost hard) white small mass which can have layers like an onion when cut.  The sebaceous cyst is filled with a liquid or pasty sometimes foul-smelling material (sebcum).  In a practical sense probably, these lesions represent a continuum that all related to congenitally or traumatically invaginated epidermis.1,2,3,4
 

Pathophysiology

  • Sebaceous cysts most frequently result from blocked sebaceous glands
  • Trauma may also be causative
  • Sebaceous cysts are sometimes hereditary

Related Anatomy

  • Sebaceous cysts are associated with sebaceous glands, which occur throughout the skin and therefore over most of the body
  • The glands and cysts are predominantly located at hair follicles

Differential Diagnosis

  • Epidermoid cyst
  • Gardner’s syndrome
  • Leiomyosarcoma
  • Molluscum contagiosum
  • Pilar (trichilemmal) cyst
  • Spinal neurenteric cysts 
ICD-10 Codes

  • SEBACEOUS CYST

    Diagnostic Guide Name

    SEBACEOUS CYST

    ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

    DIAGNOSISSINGLE CODE ONLYLEFTRIGHTBILATERAL (If Available)
    SEBACEOUS CYSTL72.3   

    ICD-10 Reference

    Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
Cyst
  • Left index finger painful sebaceous cyst (arrow) on the palmar aspect of the middle phalanx.
    Left index finger painful sebaceous cyst (arrow) on the palmar aspect of the middle phalanx.
Pathoanatomy Photos and Related Diagrams
Path specimen
  • Surgical specimen ready for submission to pathology. Note the keratin material.
    Surgical specimen ready for submission to pathology. Note the keratin material.
Symptoms
A lump under the skin that sometimes discharges, gray-white, occasionally foul smelling pasty material.
A frequently mobile lump under the skin
A painless lump unless it becomes inflamed
Typical History

The patient may have been aware of a small, painless lump just under the skin for many years and not mentioned it. On presentation, the patient will likely complain of increased size, discharge, and/or inflammation. Large, disfiguring cysts or locations that interfere with function are common complaints. 

Positive Tests, Exams or Signs
Work-up Options
Treatment Options
Treatment Goals
  • Control symptoms
Conservative
  • Because most sebaceous cysts are benign, they usually can be ignored unless painful, enlarging or infected.
  • If inflammation occurs, the cyst can be injected with a steroid to reduce swelling
  • A large cyst can be drained but recurrence is likely because cyst wall still present.
Operative
  • Excision is performed via conventional wide excision.1,3
  • Punch biopsy with delayed  minimal excision.4
  • Laser can be used to remove cyst contents, followed by minimal excision about 4 weeks later 
Treatment Photos and Diagrams
Surgical Excision of Epidermoid Cyst
  • Left index sebaceous cyst (insert). 1 - flexor tendons and sheath; 2 - note imitate adherence of cyst wall to epidermis; 3 - digital nerve.
    Left index sebaceous cyst (insert). 1 - flexor tendons and sheath; 2 - note imitate adherence of cyst wall to epidermis; 3 - digital nerve.
  • Excised cyst in clamp. Note the cyst is a soft compressible (arrow).
    Excised cyst in clamp. Note the cyst is a soft compressible (arrow).
Complications

SURGICAL COMPLICATIONS:

  • Bleeding
  • Infection
Outcomes
  • Wide excision may have excess scarring.
  • Minimal excision and punch biopsy has a risk of recurrence.
  • Laser plus minimal excision produces minimal scar which is often inconspicuous and recurrence risk is low.
Key Educational Points
  • An infected sebaceous cyst is often underestimated by clinicians as a minor problem.
  • If possible, the entire cyst lining should be removed to prevent recurrence.
  • After laser treatment, the capsule gradually loosens and crumples to a smaller capsule containing some fluid. Complete removal is then easier in the delayed operation. 
References

Cited Articles

  1. Gross S. Sebaceous cysts correlation of clinical and pathological diagnoses n three hundred cases. JAMA (1953): 152(9): 813-814.
  2. Marks JG and Miller JJ. (2013). Lookingbill and Marks Principles of Dermatology (5th ed.). Chapter 7: Dermal and Subcutaneous Growths. Elsevier (Saunders). London, New York. 2013
  3. Sempowski IP. Sebaceous cyst ten tips for easier excision. Can Fam Physician. 2006 March 10; 52(3): 315-317
  4. Wu H, Wang S, Wu L, Zheng  S. A new procedure for treating a sebaceous syst: removal of the cyst content with a laser punch and cyst wall with minimal postponed excision. Aesthetic Plast  Surg. 2009 July; 33(9): 597-599.
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