title: Adult urinary bladder tumors with rhabdomyosarcomatous differentiation: clinical, pathological and immunohistochemical studies.
abstract: Adult rhabdomyosarcoma (RMS) in the urinary bladder is rare, and is the subject of case reports and small series. It consists of sheets of small round blue cells with high nuclear cytoplasmic ratio, brisk mitosis and apoptosis. In this study, we reported one case of pure rhabdomyosarcoma and two cases of urothelial carcinomas with extensive rhabdomyosarcomatous differentiation. In addition, their immunohistochemical profile was compared to that of small cell carcinoma of the bladder. Our study showed that sufficient sampling was critical for the diagnosis of urothelial carcinoma with extensive rhabdomyosarcomatous differentiation. As adult RMS in the bladder and urothelial carcinoma with rhabdomyosarcomatous differentiation shared morphological features with small cell carcinoma of the bladder, appropriate immunohistochemical stains were necessary in the differential diagnosis. We showed both rhabdomyosarcoma and rhabdomyosarcomatous areas of the urothelial carcinoma were positive for myogenin, negative for cytokeratin and chromogranin stains. In contrast, small cell carcinoma was positive for cytokeratin, and 7 out of 9 cases were also positive for chromogranin. Both rhabdomyosarcoma and small cell carcinoma could be positive for synaptophysin, a potential pitfall to avoid. In addition, all of the tumors with rhabdomyosarcomatous differentiation were negative for FKHR rearrangement.
authors.affiliation: Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA, USA. bingz@uphs.upenn.edu
authors.forename: Zhanyong
authors.initials: Z
authors.lastname: Bing
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Zhang
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D018288:Carcinoma, Small Cell / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D002454:Cell Differentiation; D002864:Chromogranins / Q000032:analysis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D007633:Keratins / Q000032:analysis; D008297:Male; D008875:Middle Aged; D018008:Myogenin / Q000032:analysis; D011237:Predictive Value of Tests; D034802:RNA-Binding Protein EWS / Q000235:genetics; D012208:Rhabdomyosarcoma / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D016708:Synaptophysin / Q000032:analysis; D014178:Translocation, Genetic; D001743:Urinary Bladder / Q000737:chemistry* / Q000473:pathology*; D001749:Urinary Bladder Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D019459:Urothelium / Q000737:chemistry / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; D002864:Chromogranins; C503799:MYOG protein, human; D018008:Myogenin; D034802:RNA-Binding Protein EWS; D016708:Synaptophysin; D007633:Keratins