Objective: Our goal is to investigate the role and accuracy of the smooth muscle actin (SMA), Vimentin, and Smoothelin, and cluster of differentiation 10 (CD10) immunohistochemical (IHC) markers in discriminating between Muscularis propria (MP), and muscularis mucosae (MM) and myofibroblastic stromal reaction to avoid tumor over/under bladder carcinoma (BC) staging.
Material and methods: This retrospective study included 30 selected cases of BC diagnosed by transurethral resection (TUR) as positive for MP invasion based on hematoxylin and eosin (H&E) stained sections only. After radical cystectomy, 3 cases of them showed no evidence of MP invasion. We applied (SMA, Vimentin, smoothelin, and CD10) as differentiation IHC markers hoping to clarify MP invasion from other mimickers.
The Results: Vimentin and smoothelin were reliable and undependable differentiation markers that could help in bladder carcinoma staging. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy in detecting MP invasion for the smoothelin were (94.1%, 84.6%, 88.8%, 91.6%, and 90%) respectively, and those for vimentin were (94.1%, 92.3%, 94.1%, 92.3%, and 93.3%) respectively, and were improved to (94.4%, 100%, 100%, 92.3%, 96.7%) after combining smoothelin and Vimentin results. Both SMA and CD 10 could not help in differentition between myofibroblastic and smooth muscles of both MM and MP.
Conclusion:
Morphology has certainly the fundamental role in BC staging, however, in problematic cases, we suggest smoothelin and Vimentin as IHC differentiation markers that could help in BC staging on small biopsy. We encourage our colleagues to perform a larger-scale prospective studies on TUR specimens applying our recommended IHC panel, to assess their potential role in BC staging on such small biopsies.
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