Congenital Dermal Melanocytosis
Congenital Dermal Melanocytosis (Slate Gray Nevus)
Congenital Dermal Melanocytosis, previously known as Mongolian spots, represents a common birthmark characterized by macular blue-gray pigmentation caused by dermal melanocytes that failed to migrate to the epidermis during embryonic development.
Key Points
- Prevalence: Present in up to 90% of Asian, Native American, and African infants
- Age of Onset: Present at birth or appears in early neonatal period
- Gender Distribution: Equal in males and females
- Genetic Association: More common in darker-skinned populations
Clinical Features
- Appearance:
- Blue-gray to blue-green macules or patches
- Non-blanching
- Irregular but well-defined borders
- Size varies from few cm to large areas
- Surface Characteristics:
- Flat and smooth
- No surface changes
- Normal skin texture
- Associated Findings:
- Usually asymptomatic
- No tenderness
- No associated systemic manifestations
Distribution Patterns
- Common Locations:
- Sacrococcygeal region (most common)
- Buttocks
- Lower back
- Shoulders
- Extensive Forms:
- Can involve multiple sites
- May extend to extremities
- Rarely affects face or anterior trunk
Histopathological Features
- Microscopic Findings:
- Spindle-shaped melanocytes in dermis
- Located in lower two-thirds of reticular dermis
- Scattered between collagen bundles
- Normal epidermal melanocytes
- Cellular Characteristics:
- Dendritic melanocytes
- Abundant melanin production
- No cellular atypia
Management Approach
- Initial Assessment:
- Document size, location, and appearance
- Photography for monitoring
- Parental reassurance about benign nature
- Treatment Options:
- Generally no treatment required
- Q-switched laser therapy for persistent lesions
- Consider treatment for cosmetic concerns in older children
Natural Course & Prognosis
- Evolution:
- Typically fades by age 5-6 years
- Complete resolution in most cases by puberty
- 10-15% may persist into adulthood
- Monitoring:
- Annual assessment of size and color
- Document any changes
- Follow-up until resolution
Disclaimer
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