Nevus

Disease Description (Causes and Symptoms)

• Definition: A nevus is a pigmented patch (mole) that appears on the skin when melanocytes (pigment cells) form a localized cluster. It may be congenital (present at birth or during infancy) or acquired (during childhood, adolescence, pregnancy, etc.).

• Causes / pathophysiology: Developmental abnormalities of cells and genetic predisposition are known to be involved, but the exact mechanism has not been fully established. Various forms exist depending on the origin, such as the epidermis, dermis, skin appendages, or blood vessels (epidermal nevi, dermal nevi, pigmented nevi, vascular lesions, etc.).

• Main symptoms: Usually an asymptomatic, flat or raised brown-to-black spot. Some nevi may be accompanied by hair growth, and itching, bleeding, discharge, or pain may occur. Changes in shape, color, or size may raise suspicion of malignant (melanoma) transformation.

• Signs suspicious for malignancy (ABCDE rule):

  • A: Asymmetry
  • B: Unclear or irregular Border
  • C: Color variegation
  • D: Diameter > 6 mm
  • E: Evolving — changes in size, color, shape, bleeding, ulceration, etc.

Treatment Methods

• Basic principle: Observation (follow-up monitoring) is standard for asymptomatic, normal nevi. If atypical findings or suspicion of malignancy is present, a biopsy and appropriate removal are performed.
• Follow-up monitoring: Regular visual examinations and photo comparisons, including self-observation. In general, stable and asymptomatic nevi are observed once a year; for nevi with abnormal findings or in high-risk areas (hands, feet, genitalia, lips, etc.), observation at 3–6-month intervals is recommended.
• Diagnostic/therapeutic biopsy and excision:
  • For suspicious lesions, histopathological confirmation through full-thickness excisional biopsy is the principle, preferably including an adequate excision margin.
  • Shave excision, punch biopsy, or laser treatment may be considered for superficial lesions or cosmetic removal, but superficial removal alone is inadequate when malignancy is suspected.
  • For deep or large nevi, especially giant congenital nevi, staged removal or skin grafting and reconstruction may be considered.
• Non-surgical treatment (primarily for cosmetic purposes): Laser treatment, electrocautery, etc. — these have limitations, including bleeding, recurrence, and inability to confirm the pathology.
• Special considerations: Giant congenital nevi may carry a risk of malignant transformation and complications such as neurocutaneous melanosis, so a treatment plan should be established after consultation with a specialist.
• Lifestyle management and precautions: Minimize ultraviolet exposure (use sunscreen and wear hats and protective clothing) and avoid irritating the nevus (friction, cuts, or frequent scratching).

Checklist Before an Outpatient Visit (Including Example Questions)

• Recommended items to bring to the outpatient visit:
  • A list of currently used medications, including prescription drugs, OTC drugs, and supplements
  • Previous skin examination, biopsy, or pathology results, if available
  • Previous photographs for comparison of changes in the nevus, or a record of changes (when and how it changed)
  • Family history, especially of melanoma or skin cancer, and whether you have previously been diagnosed with skin cancer
• Items to record during self-observation: Nevus size (diameter), color changes, surface changes (bleeding, ulceration, scaling, or scabbing), presence of pain or itching, and the number of newly developed lesions
• Examples of materials and questions to show or ask the doctor during the outpatient visit:
  • “Explain when this photo (or record) was taken and what changes occurred.”
  • “Explain specifically when and how often itching, bleeding, or rapid growth has occurred recently.”

Examples of General Questions to Ask the Doctor

• How likely is this nevus to be malignant (melanoma)? Is an additional test, such as a biopsy, needed?
• What removal method do you recommend (excision, laser, observation, etc.), and what are the advantages and disadvantages of each method, including scarring, recurrence, and whether pathology can be confirmed?
• What degree of scarring should be expected after removal? Will reconstruction or cosmetic correction be needed?
• How often should follow-up monitoring be performed? What changes should I report immediately during self-observation?

Examples of Disease-Specific Questions

• What type of biopsy is needed for this nevus (full-thickness excision vs. punch biopsy vs. shave biopsy)? Depending on the pathology results, if additional excision is needed, how extensively will it be removed?
• In the case of a giant congenital nevus (or a nevus in a special area such as the scalp, genitalia, hands, or feet), what is the risk of malignant transformation, and what management is recommended, such as early excision, imaging tests, or neurological evaluation?

Additional guidance: If a nevus shows abnormalities in color, size, or shape, or if symptoms such as itching, bleeding, or ulceration occur, please see a dermatologist (or plastic surgeon) and undergo pathological testing if necessary.