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Patient Case: Sebaceous cyst

Patient Case: Sebaceous cyst

Discussion

A 45-year-old man presents to the dermatology clinic with a slow-growing, painless lump on his upper back that he first noticed two years ago. The lesion is round, soft, and mobile, measuring 3 cm in diameter. There is no associated redness, warmth, or tenderness. He reports no history of trauma or infection.

On examination, the lesion appears to be a subcutaneous nodule with a smooth surface, and when palpated, it has a doughy consistency. A punctum (central pore-like opening) is visible on the lesion. There are no similar lesions elsewhere on his body.

A clinical diagnosis of epidermoid cyst (sebaceous cyst) is made. The patient is reassured that the lesion is benign and is offered the option of surgical excision, especially since he finds it bothersome. If the cyst becomes inflamed or infected, incision and drainage would be considered.

Questions
  1. What is the most likely diagnosis in this patient?
    a) Lipoma
    b) Epidermoid cyst
    c) Dermatofibroma
    d) Pilonidal cyst
  2. What clinical feature helps differentiate an epidermoid cyst from other benign tumors?
    a) Rapid growth over a few weeks
    b) Presence of a central punctum
    c) Firm attachment to underlying structures
    d) Pain and ulceration
  3. Which of the following is the most appropriate management for this lesion?
    a) Observation unless symptomatic
    b) Oral antibiotics alone
    c) Immediate chemotherapy
    d) Wide surgical excision with lymph node dissection
  4. What is a potential complication of an untreated epidermoid cyst?
    a) Malignant transformation
    b) Spontaneous resolution without recurrence
    c) Secondary infection and abscess formation
    d) Development of systemic symptoms like fever and weight loss
Reveal answers

Answers

  1. (b) Epidermoid cyst
    • The lesion is slow-growing, soft, mobile, and has a central punctum, which is characteristic of epidermoid (sebaceous) cysts.
  2. (b) Presence of a central punctum
    • A central punctum is a distinguishing feature of epidermoid cysts, representing a blocked sebaceous duct, which is not seen in lipomas or dermatofibromas.
  3. (a) Observation unless symptomatic
    • Epidermoid cysts are benign and may be left untreated if asymptomatic. Surgical excision is performed if the patient finds it bothersome or if infection occurs.
  4. (c) Secondary infection and abscess formation
    • While epidermoid cysts do not become malignant, they can become infected, leading to abscess formation, requiring incision, drainage, and possibly antibiotics.