Histopathology and immunohistochemistry of COV434 original tumour. A. H&E-stained sections and immunohistochemistry for SMARCA4 and SMARCA2 of the original ovarian tumour. Two different regions of the tumour are depicted (upper and lower panels). Left images are H&E images which show the tumour grows as sheets of tumour cells with scattered follicle-like spaces. The tumour cells show complete loss of SMARCA4 (middle two panels) with foci of cytoplasmic expression of SMARCA2 (right two panels). B. Immunohistochemistry for WT1, keratin AE1/AE3, SMARCB1/INI1 and FOXL2. Tumour cells are positive for WT1 and keratin AE1/AE3 (particularly in regions with large cells, as depicted), negative for FOXL2, and have intact (normal) expression of SMARCB1/INI1. Arrow, rhabdoid cells. All images at 400x magnification.