However, there is no specific immunohistochemistry profile established for mesonephric tumors.2Positive immunostaining for CD10, CK7, calretinin, epithelial membrane antigen (EMA), PAX8, CA125, and vimentin along with negative immunostaining for CEA and EP/PR is suggestive of a mesonephric origin.9, 15Recently, GATA3 was shown to be a highly specific and sensitive marker to distinguish mesonephric origin from other carcinomas of the gynecologic tract.18The combination of GATA3, PAX8, and CD10 positivity is common in this type of carcinoma.16 The gene discussed is CALB2; the disease is carcinoma.