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Synonyms: congenital melanocytic naevus, naevocellular naevus, giant hairy naevus
Congenital pigmented naevi initially appear as flat, pigmented lesions of various sizes. They are usually solitary lesions but can be multiple. They may be very large (giant congenital naevi). Less often they may appear after birth in the first two years of life (congenital naevus tardive). As the lesion ages, it tends to become raised and may become hairy. The main clinical concern is the development of malignant melanoma.
Approximately 1-3% of all newborns have congenital pigmented naevi.
The naevus may be noted at birth or shortly afterwards. Patients may otherwise present because of cosmetic concerns or concerns about the risk of melanoma.
See separate article Black and Brown Skin Lesions, which lists "red flag" warning symptoms and signs.
- Typical small/medium lesions with no suspicious features usually require no investigation.
- Dermoscopy may be useful in assessing lesions and determining the degree of suspicion of malignant melanoma.
- Biopsy of the lesion may be used for suspicious lesions; smaller lesions can be subjected to excision biopsy, larger lesions requiring partial biopsy, possibly with dermatological/plastic surgical advice.
- Congenital pigmented naevi (particularly giant or multiple lesions) can be associated with neurocutaneous melanosis; if suspected then neuroimaging is advisable, seeking evidence of leptomeningeal melanotic lesions.
Neurocutaneous melanosis (rare congenital syndrome characterised by the presence of large or multiple congenital melanocytic naevi and benign or malignant pigment cell tumours of the leptomeninges).
- If there is a classical history, no features to suggest melanoma and no desire for cosmetic intervention by the patient, then reassurance about the nature of the lesion is all that is needed.
- Some advocate regular follow-up of congenital pigmented naevi, with recurrent photography ± dermoscopy to screen for changes indicating possible transformation to melanoma.
- The risk of malignant transformation in small and moderate-sized lesions is probably so small as to justify reassurance alone.
- Larger lesions should perhaps be monitored in a dermatology clinic.
- Those lesions that are most likely to undergo malignant change (giant or multiple) are often those least suited to prophylactic excision; seek dermatological/plastic surgical advice for such lesions.
- Giant congenital lesions may be treated in infancy by recurrent shaving of superficial layers/curettage (melanocytes are often typically in superficial layers early on); this appears to decrease the risk of subsequent malignancy but the lesions may become repigmented.
- Malignant transformation to melanoma. The lifetime risk of development of melanoma has been quoted as high as 5-7%.
- A recent well-conducted systematic review found an average risk of development of melanoma of 0.7% over 3-24 years in large, prospective studies (statistically the most reliable).
- The highest risk occurred during childhood and adolescence with median age of 7 years and mean of 15.5 years.
- The authors calculated a 465-fold increased relative risk of developing melanoma during childhood and adolescence.
- The risk of developing melanoma was by far highest in congenital melanocytic naevi of ≥40 cm in diameter (those classified as 'garment' naevi).
- It appears that the actual risk of malignant transformation in lesions of small and moderate size (a smaller area than that of the palm) is very low.
- Neurocutaneous melanosis (may cause a variety of neurological problems - particularly hydrocephalus).
- Complications associated with excision of lesions (particularly a problem with very large ones).
- Small or medium congenital melanocytic naevi carry a good prognosis with a low risk of transformation to melanoma.
- Despite the increased risk of melanoma in larger congenital pigmented naevi, the vast majority will not go on to develop melanoma.
To prevent melanoma in all people, but particularly those with large congenital pigmented naevi, advise:
- Reducing ultraviolet (UV) light exposure.
- Reducing peak sunlight exposure during most intense sun periods.
- Use of sunscreens (controversial - some suspect they may increase UV exposure).
- Use of hats and clothing to shield from intense sunlight.
Further reading and references
; Cutaneous melanoma: update on prevention, screening, diagnosis, and treatment. Am Fam Physician. 2005 Jul 1572(2):269-76.
; Congenital Nevi, Medscape, May 2011
; Giant nevi: a review. J Craniofac Surg. 2006 Nov17(6):1210-5.
; Dermoscopy for congenital melanocytic nevi. J Craniofac Surg. 2003 Sep14(5):661-5.
; Neurocutaneous melanosis. Childs Nerv Syst. 2004 Jan20(1):23-8. Epub 2003 Oct 24.
; Distinct phenotypic changes between the superficial and deep component of giant congenital melanocytic naevi: a rationale for curettage. Br J Dermatol. 2006 Mar154(3):485-92.
; Giant congenital melanocytic nevi of the trunk and an algorithm for treatment. J Craniofac Surg. 2005 Sep16(5):886-93.
; Melanoma risk in congenital melanocytic naevi: a systematic review. Br J Dermatol. 2006 Jul155(1):1-8.
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