The Risk for Melanoma in Large, Congenital Melanocytic Nevi After LCMN surgery, the risk for malignant transformation is reduced but not negligible, and scarring may affect cosmetic improvement.
Congenital melanocytic nevi (CMN) occur in 1% of newborns. CMN are classified by projected adult size: small (<1.5 cm), medium (1.5 to 19.9 cm), and large (>20 cm). Large CMN (LCMN) are rare (occurring in... 1/20,000 to 1/500,000 newborns) and are associated with a higher risk for melanoma than smaller CMN, but the true risk is unknown, and optimal management of LCMN is controversial.
Investigators evaluated 14 studies of LCMN performed during the period 1966 through 2011 that had at least 20 subjects. Among 2578 patients, 52 melanomas arose in 51 patients (2%). Age at melanoma diagnosis ranged from birth to 58 years (mean age, 12.6 years); 55% were fatal (mean age at death, 10 years; range, 0.9 to 40 years). Location was specified in 44 patients. The primary melanomas were cutaneous in 37 patients (82%), including 30 (68%) that were truncal; 7 were visceral (central nervous system, 4; bone marrow, 1; retroperitoneal, 1; dorsal muscle, 1). Among 38 LCMN with size reported, 28 were larger than 40 cm (74%); 11 (29%) were 60 cm. Satellite nevi were found in 32 patients. Melanoma incidence was estimated at 2.3 per 1000 patient-years.
The authors report that the psychosocial burden of LCMN was difficult for patients and parents, but the psychosocial benefits of surgical excision were mixed.
Comment: Although the analysis was limited somewhat by selection bias and by heterogeneity of the included studies, this systematic review demonstrates that melanoma incidence in large congenital melanocytic nevi is lower than has been historically believed. However, the risk is significantly higher for patients with CMN larger than 40 cm. In these patients, LCMN-related melanoma usually arose in childhood, and mortality was high. Nevus excision did not fully eliminate the risk — 14% of melanomas arose in visceral sites. Insufficient data were available to determine the medical and psychosocial value of prophylactic excision of LCMN.
Large, long-term, prospective studies from the U.K. have shown that surgical excision of small CMN of the head and neck produced high patient satisfaction. In contrast, tissue expansion/excision for LCMN was associated with more regrowth at surgical margins and more satellitosis, and 11% to 14% of patients with LCMN believed that surgery worsened their appearance (Br J Dermatol 2009; 160:387).
Congenital melanocytic nevi (CMN) occur in 1% of newborns. CMN are classified by projected adult size: small (<1.5 cm), medium (1.5 to 19.9 cm), and large (>20 cm). Large CMN (LCMN) are rare (occurring in... 1/20,000 to 1/500,000 newborns) and are associated with a higher risk for melanoma than smaller CMN, but the true risk is unknown, and optimal management of LCMN is controversial.
Investigators evaluated 14 studies of LCMN performed during the period 1966 through 2011 that had at least 20 subjects. Among 2578 patients, 52 melanomas arose in 51 patients (2%). Age at melanoma diagnosis ranged from birth to 58 years (mean age, 12.6 years); 55% were fatal (mean age at death, 10 years; range, 0.9 to 40 years). Location was specified in 44 patients. The primary melanomas were cutaneous in 37 patients (82%), including 30 (68%) that were truncal; 7 were visceral (central nervous system, 4; bone marrow, 1; retroperitoneal, 1; dorsal muscle, 1). Among 38 LCMN with size reported, 28 were larger than 40 cm (74%); 11 (29%) were 60 cm. Satellite nevi were found in 32 patients. Melanoma incidence was estimated at 2.3 per 1000 patient-years.
The authors report that the psychosocial burden of LCMN was difficult for patients and parents, but the psychosocial benefits of surgical excision were mixed.
Comment: Although the analysis was limited somewhat by selection bias and by heterogeneity of the included studies, this systematic review demonstrates that melanoma incidence in large congenital melanocytic nevi is lower than has been historically believed. However, the risk is significantly higher for patients with CMN larger than 40 cm. In these patients, LCMN-related melanoma usually arose in childhood, and mortality was high. Nevus excision did not fully eliminate the risk — 14% of melanomas arose in visceral sites. Insufficient data were available to determine the medical and psychosocial value of prophylactic excision of LCMN.
Large, long-term, prospective studies from the U.K. have shown that surgical excision of small CMN of the head and neck produced high patient satisfaction. In contrast, tissue expansion/excision for LCMN was associated with more regrowth at surgical margins and more satellitosis, and 11% to 14% of patients with LCMN believed that surgery worsened their appearance (Br J Dermatol 2009; 160:387).
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