Large congenital melanocytic nevi and the risk for development of malignant melanoma and neurocutaneous melanocytosis

OBJECTIVE

To determine the risk for developing malignant melanoma and neurocutaneous melanocytosis (NCM) in patients with large congenital melanocytic nevi.

DESIGN

Follow-up data suitable for calculations were available on 160 patients in the New York University Registry of Large Congenital Melanocytic Nevi who had been free of known melanomas or NCM when entered into the Registry. The cumulative 5-year life-table risks for developing melanoma and NCM were calculated. The relative risk for developing melanoma, using a control general population reference group, was determined.

RESULTS

The 160 patients (median age at entry: 14 months) were followed prospectively for an average of 5.5 years. Three extracutaneous melanomas developed: 2 were in the central nervous system (CNS) and 1 was retroperitoneal. The 5-year cumulative life-table risk for developing melanoma was 2.3% (95% confidence interval [CI]:.8-6.6) and the relative risk was 101 (95% CI: 21-296). No melanoma occurred within a large congenital melanocytic nevus. Four patients developed manifest NCM, 2 with CNS melanomas. The 5-year cumulative life-table risk for developing NCM was 2.5% (95% CI:.8-7.2). Ten patients were excluded from the calculations because of preexisting disease on entry into the Registry: 5 with manifest NCM and 5 with melanomas (3 in large congenital melanocytic nevi, 1 in nonnevus skin, and 1 unknown primary).

CONCLUSIONS

Patients with large congenital melanocytic nevi are at increased risk for developing melanomas. There is also a significant increased risk for developing NCM. The high incidence of CNS involvement may influence decisions concerning treatment of the large congenital melanocytic nevi.

Differential expression of nm23 H-1 protein in conjunctival melanoma and potential precursor lesions

Loss of nm23 gene expression is believed to enhance metastatic spread in diverse human tumors, including skin melanoma. The purpose of this work was to determine the pattern and prognostic relevance of nm23 protein immunoexpression in conjunctival melanoma and potential precursor lesion. Formaldehyde-fixed, paraffin-embedded conjunctival specimens comprising 85 melanocytic lesions (nevi, primary aquired melanosis with and without atypia and primary and locally recurrent malignant melanomas) from 73 patients were used. Sections from all specimens were examined by light microscopy to assess diverse prognostic parameters. Additional sections were then immunostained for nm23 H-1 protein and the immunoreactivity was assessed semi-quantitatively. Survival data for all patients were retrieved from the National Causes of Death Registry of Sweden.Nm23 H-1 protein was differentially expressed in conjunctival melanocytic lesions, however loss of immunoexpression was not more common in melanocytic lesions asociated with a high risk of malignant transformation. Also, primary and recurrent conjunctival melanomas showed an essentially similar nm23 expression pattern and we could not associate the pattern of nm23 immunoexpression with an increased risk for malignant transformation or locally recurrent disease. While there was a tentative separation between cause-specific survival curves after excision for low and high nm23 expression conjunctival melanoma, there was no statistically significant association with metastatic death of patients. However, loss of nm23 protein immunoexpression may still be of some importance as a marker for prognosis in conjunctival melanoma because the present study could only detect large differences in survival. Our results suggest that any potential prognostic value of nm23 immunoexpression would be independent of other markers, underlining the importance of further studies.