HLA expression in choroidal melanomas: correlation with clinicopathological features.

PURPOSE

In this retrospective study, we analyzed the relevance of human leukocyte antigen (HLA) expression to clinical behavior of uveal melanoma and correlated it with conventional light microscopic parameters.

METHODS

HLA class I antigen and Beta 2 microglobulin expression were analyzed in 45 primary choroidal melanoma lesions by immunoperoxidase staining with monoclonal antibodies to HLA class I antigen and beta 2 microglobulin and correlated with the known clinicopathological parameters. Immunoanalysis was done by a semi quantitative method. The tumors were divided into 3 groups. Group A: Tumors with no extrascleral extension/no liver metastases, group B: tumors with only extrascleral extension and group C: tumors with liver metastases. For statistical analysis we analyzed the negative, weak (heterogeneous) and the positive expression of HLA and beta 2 microglobulin with known clinicopathological parameters.

RESULTS

In-group A (n = 35) tumors with no extrascleral extension and no liver metastases HLA class I antigen and beta 2 microglobulin are negative (absent staining) in 30 choroidal melanomas. In-group B (n = 4) they are weak (heterogeneous) in 3 tumors. In-group C (n = 6) all the 6 tumors have a positive (bright staining) immunoexpression. No statistical significance was obtained when HLA and beta 2 microglobulin immunoreactivity was compared against largest tumor diameter (LTD), tumor infiltrating lymphocytes (TIL), mitosis and nuclear grade. The difference of HLA class I and beta 2-microglobulin imunoreactivity among the various cell types spindle, mixed and epithelioid was statistically significant (p = 0.003), (p = 0.004). The difference in immunoreactivity between tumors with no liver metastases and tumors with liver metastases was statistically significant (p < 0.001).

CONCLUSIONS

HLA class I antigen and beta 2 microglobulin are negative in melanomas with no extrascleral extension and liver metastases and weak in melanomas with extrascleral extension and are positive in melanomas with liver metastases. HLA expression is independent of the conventional markers in uveal melanoma.