Immunohistochemical Panel of Undifferentiated Orbital Metastatic Carcinomas

Purpose: To examine the applicability of an immunohistochemical panel of seven monoclonal antibodies to identify the primary site of poorly differentiated orbital metastatic carcinomas. Material and Methods: Immunohistochemistry was performed to detect cytokeratin (CK) 7, CK20, thyroid transcription factor-1 (TTF-1), BRST1, BRST2, carcinoembryonic antigen (CEA) and prostate-specific antigen (PSA) in seven cases of poorly differentiated orbital metastases. Of the seven cases, four were female and three male. The youngest patient was thirty-six while the oldest was eighty-eight years of age. Results: The immunohistochemical panel alone was helpful to identify the primary source of the metastatic lesion in three out of the seven cases. Two of them were metastatic breast carcinomas (BRST1, BRST2 positive) and one was a prostate carcinoma (PSA positive). By correlating the immunohistochemical results with the previous clinical history, the primary site could be identified in two more cases. In those metastatic lesions, the positive staining for CK7, CK20, and CEA, associated with negative staining for BRST1, BRST2, PSA and TTF-1, indicated bladder as the probable primary site. In two out of seven cases, the metastatic tumor was only positive for CEA, therefore a primary site could not be identified. Conclusions: An immunohistochemical panel of poorly differentiated orbital metastases is helpful in the identification of the primary tumor site. The association of seven markers with the patient's clinical history allowed for the positive identification of the primary tumor in the majority of these cases.