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Patient Case: Epidermoid Cyst

Patient Case: Epidermoid Cyst

Discussion

A 35-year-old man presents to the dermatology clinic with a slow-growing, painless lump on his upper back that he first noticed six months ago. The lump has gradually increased in size but does not cause significant discomfort. However, he reports occasional tenderness when pressure is applied.

On examination, there is a 3 cm, round, mobile, and firm nodule with a smooth surface and a central punctum. The lesion is non-tender but slightly compressible. No signs of redness, warmth, or discharge are noted. The patient denies any history of trauma or similar lesions in the past.

The physician diagnoses an epidermoid cyst, a benign lesion resulting from the accumulation of keratin within a blocked hair follicle. The patient is reassured that the cyst is harmless but is offered surgical excision to prevent future enlargement or infection.

Questions
  1. What is the most likely diagnosis in this patient?
    a) Lipoma
    b) Epidermoid cyst
    c) Dermatofibroma
    d) Sebaceous adenoma
  2. What is a characteristic feature of an epidermoid cyst?
    a) Presence of a central punctum
    b) Rapid ulceration
    c) Irregular, fixed borders
    d) Association with malignant transformation
  3. What is the best management option for this patient?
    a) Observation and reassurance
    b) Oral antibiotics for 10 days
    c) Intralesional steroid injection
    d) Complete surgical excision
  4. Which of the following is the primary content of an epidermoid cyst?
    a) Sebum and pus
    b) Keratin and lipid debris
    c) Fibrous connective tissue
    d) Blood and inflammatory cells
Reveal answers

Answers

  1. (b) Epidermoid cyst – The slow-growing, mobile, firm nodule with a central punctum is highly characteristic of an epidermoid cyst. Lipomas are typically soft and lack a punctum, while dermatofibromas are firm and tethered to the skin.
  2. (a) Presence of a central punctum – Epidermoid cysts often have a central opening, representing the blocked follicular orifice from which keratin accumulates. This helps differentiate them from lipomas, which do not have a punctum.
  3. (d) Complete surgical excision – While the cyst is benign, surgical excision is the definitive treatment to prevent recurrence or secondary infection. Observation is reasonable if the patient is asymptomatic, but antibiotics and steroids are not first-line treatments.
  4. (b) Keratin and lipid debris – Epidermoid cysts are filled with keratinous material, derived from epithelial cells. This differentiates them from sebaceous cysts, which contain sebum, and abscesses, which contain pus and inflammatory cells.