Brown Hair-Bearing Patch in a Child: Diagnosis and Management
Most Likely Diagnosis
The most likely diagnosis is a congenital melanocytic nevus (CMN), which characteristically presents as a brown pigmented lesion with hair growth (hypertrichosis) that is present at birth or appears shortly thereafter. 1, 2
However, if this lesion is located over the midline spine (particularly lumbosacral region), urgent evaluation for underlying spinal dysraphism is mandatory, as midline hypertrichosis is a high-risk cutaneous marker for congenital spinal cord malformations. 1
Critical Initial Assessment Algorithm
Step 1: Determine Location
Midline spinal location (especially lumbosacral): This is a high-risk marker requiring urgent neurosurgical evaluation 1
Non-midline or non-spinal location: Proceed with CMN evaluation 1
Step 2: Measure and Classify Size
- Document current size and calculate projected adult size (multiply by 1.5-2x for trunk, 3x for extremities) 1, 3
- Small CMN: <1.5 cm projected adult size 1
- Medium CMN: 1.5-20 cm projected adult size 1
- Large CMN: 20-40 cm projected adult size 1
- Giant CMN: >40 cm projected adult size (highest melanoma risk 3-8%) 1, 2
Step 3: Count Satellite Lesions
- Presence of ≥10 satellite nevi significantly increases risk for neurocutaneous melanosis 3, 4
- Multiple CMN (>1 lesion) warrant MRI screening 4
Immediate Red Flags Requiring Urgent Dermatology Referral (Within Days)
Refer immediately if any of the following are present: 3, 5
- Rapid or asymmetric growth beyond expected proportional growth with the child 3
- Color variation or heterogeneous darkening 3
- Development of nodules or papules (palpate deeply—melanoma can present as deep nodules without surface color change) 3, 5
- Bleeding, ulceration, or persistent erosions 3
- Pain or significant pruritus 3
Screening for Neurocutaneous Melanosis
Obtain brain and spine MRI (without contrast, no anesthesia needed in young infants) if: 1, 3, 4
- Medium-to-large sized CMN (>1.5 cm projected adult size) 3
- Multiple CMN (>1 lesion) or ≥10 satellite lesions 3, 4
- Giant CMN (>40 cm projected adult size) 3
Rationale: 10% of screened patients show intraparenchymal melanosis, which carries the highest melanoma risk (up to 8% in multiple CMN, predominantly CNS melanoma) 3, 4
Melanoma Risk Stratification
Lifetime melanoma risk varies by CMN size: 1, 2
- All CMN: 0.7-2.2% overall risk 1
- Giant CMN: 3-10% risk 1, 2
- Timing: 50% of melanomas develop by age 2,80% by age 7 in giant CMN 6
- Location: In multiple CMN, majority of melanomas occur in the CNS rather than skin 3
Surveillance Protocol
Initial Monitoring (First Year)
- Every 3 months for lesions showing growth or concerning features 3
- Perform visual inspection AND palpation (melanoma can be deep without surface changes) 3, 5
- Serial photography to document changes 3
Long-Term Monitoring
- Annual dermatology evaluation minimum for small-to-medium stable CMN 3, 5
- More frequent visits (every 3-6 months) for large/giant CMN or multiple lesions 3
- Teach families to monitor for ABCDE changes (Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution) 1
Management Approach
Conservative Management (Preferred for Most Cases)
Observation is appropriate for uncomplicated small and medium CMN. 1
Expected benign changes over time include: 3, 5
- Proportional growth with the child 3
- Pigmentation becoming more mottled, speckled, or heterogeneous 3
- Surface becoming more raised, verrucous, or papillated 3
- Increased hypertrichosis (hair growth) 1, 3
- Many CMN lighten over time without intervention 1
Surgical Considerations
Indications for surgery may include: 1
- Functional impairment 1
- Difficulty with clinical monitoring 1
- Significant psychosocial impact (though this should be carefully weighed, as 54% of adolescents report moderate-to-extremely large impact on quality of life) 1
- Development of suspicious nodules or changes 3
Surgical options for large/giant CMN: 1
What NOT to Do
Avoid ablative procedures (lasers, curettage, dermabrasion) because: 3, 5
- They obscure future melanoma evaluation 3, 5
- Frequent pigment recurrence occurs 3, 5
- They do not remove deep melanocytes where melanoma can arise 3
If biopsy is needed, perform complete excisional biopsy rather than shave biopsy to allow comprehensive histological assessment 3, 5
Hair Management
For hypertrichosis (excessive hair growth): 1
- Infants: Simple trimming is adequate 1
- Older children: Shaving, waxing, threading, chemical depilation, or trimming are low-risk options 1
- Permanent options: Laser hair reduction or electrolysis require serial treatments but cause histologic changes that may complicate monitoring 1
Family Counseling and Support
Provide anticipatory guidance about: 1
- Natural history of CMN (many lighten over time, surface changes are expected) 1
- Low but present melanoma risk 1
- Importance of sun protection (standard recommendations: sunscreen, protective clothing, hats) 1
- Psychosocial support resources and patient advocacy groups 1
Warn families that some interventions can worsen appearance (disfiguring scars, keloids, recurrent nevi) 1
Common Pitfalls to Avoid
- Failing to palpate the lesion: Melanoma in CMN can present as deep dermal/subcutaneous nodules without overlying color change 3, 5
- Missing spinal dysraphism: Always assess location—midline spinal hypertrichosis requires neurosurgical evaluation 1
- Performing ablative procedures: These compromise future melanoma surveillance 3, 5
- Inadequate screening for neurocutaneous melanosis: Medium-to-large or multiple CMN need MRI 3, 4
- Assuming all growth is malignant: Proportional growth with the child is expected and benign 3