What are the implications and management of an intradermal (within the skin) nevus (mole) with congenital (present at birth) features?

Intradermal Nevus with Congenital Features: Implications and Management

An intradermal nevus with congenital features indicates a melanocytic nevus that is present at birth or develops early in life, with nevus cells located primarily in the dermis, requiring regular monitoring due to a small but present risk of malignant transformation. 1

Understanding Intradermal Nevi with Congenital Features

• Congenital melanocytic nevi (CMN) are present in approximately 1-3.6% of newborns and carry a lifetime melanoma risk of 0.7-1.7% 1
• Intradermal nevi have melanocytes confined to the dermis, which gives them their characteristic appearance and texture 2
• When an intradermal nevus has "congenital features," it means the histopathology shows characteristics typical of nevi present at birth, such as deeper extension of nevus cells and involvement of adnexal structures 3

Risk Assessment

• While traditionally thought to have lower malignant potential than junctional or compound nevi, intradermal nevi with congenital features still carry some risk of melanoma development 4
• The risk of malignant transformation is higher in:
  • Larger lesions (>40 cm in diameter) 3
  • Lesions located on the trunk 3
  • Multiple congenital nevi 3
  • Nevi with atypical features or changes 1

Monitoring and Management

• Regular clinical and dermoscopic evaluation is essential for all congenital nevi, including intradermal types 1

• Concerning changes that warrant immediate evaluation include:

  • Rapid growth 3
  • Bleeding or ulceration 3
  • Pain or discomfort 3
  • Development of nodules 3
  • Color changes, especially darkening or variegation 1

• Photography is recommended to document the baseline appearance and track changes over time 1

When to Consider Removal

• Complete excision should be considered for:

  • Nevi with suspicious changes suggestive of malignant transformation 2
  • Lesions in difficult-to-monitor locations 2
  • Cases where the diagnosis is uncertain 5

• The decision for removal should take into account:

  • Patient age and overall health 3
  • Size and location of the nevus 3
  • Family preference after thorough risk-benefit discussion 3

Biopsy and Removal Techniques

• For suspicious lesions, complete excisional biopsy is preferred over shave biopsy to allow comprehensive histological assessment 2
• Avoid partial removal of melanocytic nevi as this may result in pseudomelanoma (clinical and pathological picture resembling melanoma) 2
• For confirmed melanoma arising in a congenital or atypical nevus, ensure removal of both the melanoma with appropriate margins and the entirety of the residual nevus 2

Common Pitfalls to Avoid

• Dismissing intradermal nevi as always benign - rare cases of melanoma arising from intradermal nevi have been reported 4
• Failing to recognize that flat melanocytic areas adjacent to intradermal nevi may represent malignant transformation 4
• Using diagnostic shave biopsies for suspicious lesions, which can compromise accurate diagnosis and staging 2

Follow-up Recommendations

• Patients with congenital nevi should be taught self-examination techniques 2

• Follow-up frequency should be determined by the size, location, and characteristics of the nevus:

  • Higher-risk nevi may require visits every 3 months initially 3
  • After the first year, in the absence of concerning features, visit frequency can gradually decrease 3
  • A minimum of yearly dermatologist evaluation is appropriate for higher-risk nevi 3

• Between visits, patients or caregivers should regularly inspect and palpate the nevus and report any concerning changes promptly 3