Test Details: Immunohistochemical testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody. CA125 is normally expressed by glandular epithelium of different organs and is highly expressed in ovarian carcinomas. Serum CA125 is also used to monitor the progression of ovarian carcinoma. Among non-epithelial tumours, CA125 expression may be observed in epithelioid sarcoma and desmoplastic small round cell tumour.