WT1 and malignant epithelioid mesothelioma: For epithelioid mesothelioma, the most common positive markers are calretinin, cytokeratinin 5/6 (CK5/6), Wilms tumor-1 (WT1) antigen, and podoplanin.18 All biopsy specimens obtained from our patient were positive for calretinin, CK5/6, and WT1 (Fig 2), and negative for PAX8, mammoglobin, CK20, CDX2, and GCDFP15l.