Expression pattern of type IV collagen in sporadic dysplastic melanocytic nevi.

OBJECTIVE

To investigate the expression and distribution pattern of type IV collagen in dysplastic nevi (DN) and to determine whether DN exhibits a morphologic difference from common melanocytic nevi (CMN) and cutaneous malignant melanomas (MM) and therefore can be classified as a separate entity.

STUDY

DESIGN

We examined 33 DN specimens, 18 CMN specimens, and 10 MM specimens. The streptavidinbiotin immunoperoxidase method was used for immunostaining.

RESULTS

No staining was observed in most of the CMN. Twenty-one of 33 DN showed a continuous pattern of type IV collagen surrounding junctional nests in a concentric fashion while a discontinuous immunostaining pattern was observed in remaining cases. Six of 10 MM showed a continuous staining pattern; 2 exhibited discontinuous staining; and in 2 cases, no immunostaining was observed. The expression pattern of type IV collagen in DN was statistically different from CMN and MM.

CONCLUSION

Our results suggest sporadic DN is biologically different from CMN in terms of the capacity to synthesize type IV collagen, demonstrating that DN is not only morphologically but also biologically a different entity from CMN.