Multilocular renal cyst. Immunohistochemical and lectin-binding study

Multilocular renal cyst is an uncommon lesion of uncertain pathogenesis seen in children and adults. We report the immunohistochemical and lectin-binding profiles of three MRC occurring in adults. All cases had strong and uniform cytoplasmic staining of lining epithelial cells for keratin and binding sites for arachis hypogaea lectin, similar to that seen for the distal convoluted tubules or collecting ducts in normal kidney. However, we found variable expression of other distal nephron markers, including epithelial membrane antigen and Ber-EP4. Furthermore, lining cells in some lesions coexpressed proximal nephron markers such as alpha-1-antitrypsin and lysozyme, as well as binding sites for lotus tetragonolobus lectin. Immunostaining for type IV (basement membrane) collagen demonstrated a continuous subepithelial basement membrane zone and basal laminae surrounding desmin-positive stromal cells. Areas of active collagen synthesis and stromal procollagen deposition were visualized within the interlocular septae using a monoclonal antibody to type I procollagen. Significant proliferative activity was not detected in the lining epithelium or stroma using the anti-proliferating cell nuclear antigen. In conclusion, MRC show aberrant tubular epithelial glycoprotein and glycoconjugate expression, low proliferative activity, and associated activation of interlocular stromal cells.