Immunohistochemical differentiation between muscularis mucosae and muscularis propria for improving the staging of bladder cancer in patients undergoing transurethral resection of bladder tumours

Microscopic differentiation between muscularis mucosae (MM) and muscularis propria (MP) of the bladder in the material obtained during transurethral resection (TUR) remains difficult. The study was aimed at determination of the usefulness of immunohistochemical staining in this context. Forty-seven TUR specimens were stained with 5 mouse anti-human antibodies: anti-desmin, anti-filamin, anti-type IV collagen, anti-smoothelin, and anti-vimentin. Slides were assessed under light microscopy and the intensity of the immune reaction within MM and MP was evaluated on a four-level visual scale as follows: negative (0) and weakly (1), moderately (2), or strongly (3) positive. MM was identified in 27 patients (57.4%). The modal values of reaction intensity in MM and MP was 0 and 2 for desmin (p > 0.05), 2 and 2 for filamin (p = 0.01), 2 and 2 for type IV collagen (p > 0.05), 1 and 2 for smoothelin (p = 0.03), and 2 and 0 for vimentin (p = 0.02), respectively. Identical intensity within MM and MP was observed in 7.1%, 28.6%, 20%, 30.1%, 5.6%, respectively. Immunohistochemistry can help differentiate between MM and MP in TUR specimens. As of yet, no single marker can reliably differentiate between MM and MP; however, a combination of anti-filamin, anti-smoothelin, and anti-vimentin antibodies may be reasonable for diagnostic purposes.