//fpnotebook.com/
Congenital Melanocytic Nevus
Aka: Congenital Melanocytic Nevus, Congenital Melanocytic Nevi, Garment Nevi, Giant Congenital Nevi, Birthmark, Giant Hairy Nevi, Bathing Trunk Nevi, Congenital Nevus, Congenital Nevi
- See Also
- Atypical Nevus
- Melanoma
- Melanoma Risk Factors
- Speckled Lentiginous Nevus
- Epidemiology
- Prevalence: Up to 2% of newborns
- Pathophysiology
- Neural crest Melanocytes and their precursors with disrupted migration
- Signs
- Brown to black lesions that are typically flat (but can be elevated, and may thicken as children get older)
- Size can vary from a few millimeters to several centimeters to involving an entire region of the body
- Hair is variably present
- Typically with uniform pigmentation
- Types: Speckled Lentiginous Nevus (Nevus Spilus)
- Variant of Congenital Nevi
- Hairless round to irregularly shaped brown nevus
- Larger nevus contains 1-3 mm dots of dark brown pigmentation (may be elevated)
- Diameter ranges from 1-20 cm
- Malignant transformation is uncommon but can occur
- Size of lesion directs management - follow the same protocols for Congenital Nevi based on size below
- Observe and biopsy or excise lesions if atypical
- Lab: Histology
- Localized to the lower Dermis
- Differential Diagnosis
- Cafe-Au-Lait Spots
- Complications: Melanoma
- Small Congenital Nevi <1.5 cm (adult size) rarely progress to Melanoma
- Medium size lesions may develop Melanoma in up to 0.7% of cases
- Giant Congenital Nevi >20 cm (adult size) carry up to a 7% lifetime risk of Melanoma
- Half of Melanomas in Giant Congenital Nevi occur by age 3-5 years
- Management
- Large Congenital Melanocytic Nevi (Giant Congenital Nevi)
- Criteria
- Garment Nevi or Giant Congenital Nevi: >14 cm in infants (>20 cm in adults)
- Large Congenital Nevi: >12 cm head or >7 cm elsewhere in infants (>20 cm adults)
- Precautions
- As noted above, Melanoma development in Giant Congenital Nevi occurs before age 3-5 years in 50% of cases
- Excise these lesions as infants or young children (before age 3-5 years)
- Observation may miss transformation due to depth of nevus
- Protocol
- Excise lesion as soon as possible (or currettage during the first 2 weeks of life)
- Close observation for recurrence (excision does not eliminate risk completely)
- Medium Congenital Melanocytic Nevi
- Criteria: 0.5 to 7 cm in infants (1.5 to 20 cm in adults)
- Protocol
- Close observation by dermatology
- Consider Punch Biopsy for risk stratification
- Deeper dermal lesions may elude early detection of malignant transformation despite observation
- Small Congenital Melanocytic Nevi
- Criteria: <0.5 cm in infants (<1.5 cm in adults)
- Low malignant potential (especially pre-Puberty)
- Protocol
- Close observation by primary provider
- If excised, it is safe to wait until after Puberty
- References
- Habif (2003) Clinical Dermatology, 4th ed.. Mosby, p. 773-813
- Berg (2003) Melanoma Res 13:441-5 [PubMed]
- Krengel (2006) Br J Dermatol 155:1-8 [PubMed]
- McLaughlin (2008) Am Fam Physician 77:56-60 [PubMed]