Comparative immunohistochemical oestrogen receptor analysis in primary and metastatic uveal melanoma.

Abstract

The investigation reported here was carried out to determine the oestrogen receptor status of metastatic and primary uveal melanomas. A series of 23 primary and 24 metastatic formalin-fixed paraffin-embedded choroidal melanomas were analysed immunohistochemically with the monoclonal antibody (MAb) 1D5 using the avidin-biotinylated peroxidase method and antigen retrieval with microwaves. Melanophages were identified with MAb PG-M1 to macrophages. None of the primary or metastatic melanomas contained tumour cells that would have shown a nuclear immunoreaction for oestrogen receptors with MAb 1D5. However, in 20 of the 23 primary tumours and in 14 of the 24 metastases 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 cytoplasm was strongly labelled with MAb PG-M1, identifying them as cross-reacting macrophages. 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-oestrogens also act by other mechanisms on both tumour and host tissues, the lack of oestrogen receptors does not automatically negate their therapeutic effect in disseminated melanoma.