PDPN and neoplasm: PDPN is a mucin-type transmembrane glycoprotein of 38-kDa molecular weight and can be demonstrated in a variety of normal cells, e.g. peritoneal mesothelial cells, follicular dendritic cells in lymphoid tissue (17) and is known to be expressed in various tumours (e.g. germ cell tumours and squamous cell carcinoma) (18).