What is a dermoid cyst?

Dermoid Cyst: Definition, Characteristics, and Management

A dermoid cyst is a benign congenital tumor classified as a mature cystic teratoma, most commonly found in the ovaries, containing tissue derived from multiple germ cell layers including skin, hair, teeth, and cartilage. 1

Characteristics and Prevalence

• Dermoid cysts (mature teratomas) are the most common type of ovarian germ cell tumors, accounting for approximately 20% of all ovarian tumors 1
• They are predominantly found in younger women of reproductive age 1
• While most common in ovaries, dermoid cysts can occur in various locations throughout the body:
  • 7% are found in head and neck region 2
  • Can appear in the floor of mouth, tongue, lips, nasal region, orbital region, and other sites 2, 3, 4

Pathophysiology

Dermoid cysts develop from entrapped ectodermal tissue during embryologic development 5. They typically contain:

• Sebaceous fluid
• Tissues from all three germ cell layers:
  • Ectoderm (skin, hair, brain tissue)
  • Mesoderm (muscle, fat, teeth, bone, cartilage)
  • Endoderm (mucous and ciliated epithelium) 6

Diagnostic Features

Clinical Presentation

• Usually presents as a slow-growing mass
• Often asymptomatic until they reach a significant size
• May cause symptoms based on location (e.g., pelvic mass in ovarian dermoids)

Imaging Characteristics

• Pathognomonic appearance on imaging with distinctive features:
  • Fatty and calciferous content visible on MRI 1
  • Hyperechoic components with acoustic shadowing on ultrasound 1
  • May contain hyperechoic lines and dots (representing hair) 1
  • Fluid-fluid levels with floating fat 1
  • May contain visible teeth or bone fragments

Management Approach

Ovarian Dermoid Cysts

For typical ovarian dermoid cysts <10 cm:

• Premenopausal patients:

  • Optional initial follow-up at 8-12 weeks
  • If not surgically removed, annual ultrasound surveillance 1
  • Fertility-preserving surgery is recommended when intervention is needed 1

• Postmenopausal patients:

  • May be considered for annual ultrasound follow-up if not surgically excised
  • Higher vigilance required due to small risk of malignant transformation 1

Management of Changing Dermoid Cysts

If there is:

• Changing morphology
• Developing vascular component

Then:

• Premenopausal: Referral to ultrasound specialist or MRI 1
• Postmenopausal: Direct referral for MRI recommended 1

Surgical Approach

• Complete surgical excision is the standard treatment 2, 3
• Approach depends on cyst location and extent 3
• For ovarian dermoids, fertility-sparing surgery is recommended in younger women 1
• For dermoids in critical locations (e.g., midline skull), preoperative imaging is essential to rule out intracranial extension 5

Complications and Prognosis

• Generally benign with excellent prognosis after complete excision
• Potential complications:
  • Torsion (in ovarian dermoids)
  • Rupture leading to chemical peritonitis
  • Malignant transformation (rare, 1-2% of cases) 6
  • Local complications like inflammation, infection, or bone resorption 3

Important Considerations

• Dermoid cysts in certain locations (nasal, midline skull) require thorough imaging before surgery to rule out intracranial connections 3, 5
• Differential diagnosis for midline masses includes epidermoid cyst, encephalocele, glioma 5
• Complete surgical excision is essential to prevent recurrence 4