الفهرس 
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Abstract
Urinary bladder cancer is a significant cause of morbidity and mortality worldwide. The single most important prognostic factor in urothelial carcinoma is pathological stage, which includes the anatomic depth of invasion on which major therapeutic decisions are made. Correct assessment of invasion of muscularis propria by carcinoma in bladder biopsy requires the discrimination between muscularis mucosae (MM) and muscularis propria (MP).
Fragmentation of biopsy, poor orientation, thermal artifacts, inflammatory response and infiltrative tumor cells splaying the muscle bundles hyperplastic muscularis mucosa (HMM) complicate proper differentiation between MM and MP.
Smoothelin is a cytoskeletal protein that is specifically expressed in fully differentiated contractile smooth muscle.
Vimentin is the most widely distributed intermediate filament and is expressed in virtually all mesenchymal tissues.
This study aimed at evaluation of diagnostic value of smoothelin and vimentin expression both singly and in combination for differentiation between MM and MP.
This retrospective study was conducted on 70 urinary bladder specimens, retrieved from the archives of Pathology Departments, Faculty of Medicine, Menoufia University and Cairo University spanning the period between January 2014 and January 2016.
The studied cases includeded 59 cases of primary urinary bladder carcinoma received as cystectomy specimens and 11 cystitis cases received as TURBT specimens.
Histologic type, grade, invasion of MP and type of muscles included were all assessed in H&E stained sections in malignant cases.
Muscularis mucosa (MM) was identified histologically in 40 cases by being thin slender bundles arranged in a single layer of interrupted, wispy dispersed, or continuous associated with vascular plexus whereas muscularis propria (MP) was morphologically designated in all cases (70 cases) and was identified by being coarse muscle bundles with rounded contours not associated with vascular plexus.
The method used for immunostaining was streptavidin-biotin amplified system. Two primary antibodies have been used: smoothelin [R4A] and vimentin (V9)
Smoothelin was positive in all MP mostly moderate to strong but one case was mild, while mostly negative to weak in MM but 3 cases were moderate to strong. So intensity of smoothelin expression showed significant difference (P=0.000) between MM and MP with 97.5% sensitivity and 95% specificity and the percentage of smoothelin expression was significantly higher in MP compared to MM (P=0.000) with 95.7% sensitivity and 85% specificity using 65% as a cutoff point..
Vimentin was negative in MP and showed positive expression in 32/40 cases (80%) of MM with a statistical significant difference (P=0.000) with 80% sensitivity and 100% specificity.
Combined moderate to strong smoothelin and negative vimentin offered 100% sensitivity and 100% specificity towards the identification of MP.
There were no statistical significance between the studied clincopathological parameters and smoothelin (positivity, intensity, percentage) and vimentin expr.