COMPARATIVE IMMUNOHISTOCHEMICAL ESTROGEN-RECEPTOR ANALYSIS IN PRIMARYAND METASTATIC UVEAL MELANOMA

Background: The investigation reported here was carried out to determi ne the oestrogen receptor status of metastatic and primary uveal melan omas. Methods: A series of 23 primary and 24 metastatic formalin-fixed , paraffin-embedded choroidal melanomas were analysed immunohistochemi cally with the monoclonal antibody (MAb) 1D5 using the avidin-biotinyl ated peroxidase method and antigen retrieval with microwaves. Melanoph ages were identified with MAb PC-Mi to macrophages. Results: None of t he primary or metastatic melanomas contained tumour cells that would h ave shown a nuclear immunoreaction for oestrogen receptors with MAb 1D 5. However, in 20 of the 23 primary tumours and in 14 of the 24 metast ases a variable number of infiltrating cells showed a strong positive cytoplasmic immunoreaction with MAb 1D5. The cells contained pigmented cytoplasmic granules that resisted bleaching of melanin and their cyt oplasm was strongly labelled with MAb PC-Mi, identifying them as cross -reacting macrophages. Conclusion: Oestrogen receptors can not be used as a prognostic indicator if anti-oestrogen therapy is considered for treatment of metastatic uveal melanoma. However, because anti-oestrog ens also act by other mechanisms on both tumour and host tissues, the lack of oestrogen receptors does not automatically negate their therap eutic effect in disseminated melanoma.