Adult urinary bladder tumors with rabdomyosarcomatous differentiation: Clinical, pathological and immunohistochemical studies

Zhanyong Bing,Paul J Zhang

doi:10.1186/1746-1596-6-66

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.

Highlights

Rhabdomyosarcoma occurs much more commonly in children than in adults in genitourinary tract, in which more than 90% is embryonal, mostly botryoid type
Adult rhabdomyosarcoma of urinary bladder can have morphologic features overlapping with small cell carcinoma and poorly differentiated urothelial carcinoma with rhabdomyoblastic differentiation [7]
We reported three cases of primary rhabdomyosarcomatous tumor of the urinary bladder, two of them were diagnosed as carcinoma with extensive rhabdomyosarcomatous differentiation based on very minor carcinomatous elements identified and

Summary

Introduction

Rhabdomyosarcoma occurs much more commonly in children than in adults in genitourinary tract, in which more than 90% is embryonal, mostly botryoid type. Adult rhabdomyosarcoma is extremely rare [1,2,3,4,5,6,7]. Because of its rarity in adults, proper diagnosis and classification can be a challenge. To make this matter more complicated, rhabdomyoblastic differentiation is one of commonly seen heterologous elements in sarcomatoid carcinoma of urinary bladder [7]. Adult rhabdomyosarcoma of urinary bladder can have morphologic features overlapping with small cell carcinoma and poorly differentiated urothelial carcinoma with rhabdomyoblastic differentiation [7]. We reported three cases of primary rhabdomyosarcomatous tumor of the urinary bladder, two of them were diagnosed as carcinoma with extensive rhabdomyosarcomatous differentiation based on very minor carcinomatous elements identified and

Material and methods

Manufacturer Dako

No perivesicular tissue

Discussion

Findings

Small cell carcinoma