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Plasmacytoid urothelial carcinoma of the urinary bladder – a review of the literature
Plasmacytoid urothelial carcinoma is a new variant of urothelial carcinomas that was added to the World Health Organization (WHO) classification list in 2004; therefore, in view of its rarity, most practitioners may not be familiar with its biological behaviour. Various internet databases were searched to identify cases of plasmacytoid urothelial carcinoma of the urinary bladder in order to document the presentation, investigation, management, treatment and outcome of the disease. In addition, the only reported case of plasmacytoid urothelial carcinoma of the ureter is included. Plasmacytoid urothelial carcinoma of the urinary bladder is a rare variant of urothelial carcinoma and fewer than 100 cases have been reported in the literature. It is an aggressive subtype of urothelial carcinoma with plasmacytoid features and the diagnostic features include mimicking haematolymphoid malignancy, a dyscohesive invasive pattern, eccentric nuclei, evidence of prominent eosinophilic cytoplasm (amphophilic cytoplasm may also be observed) and intracytoplasmic mucin-positive lumina may be present. Patients often present with plasmacytoid urothelial carcinoma at a late stage and exhibit peritoneal surface spread. Mucin stains may reveal intracytoplasmic lumina and plasmacytoid urothelial carcinomas tend to depict immunohistochemical staining characteristics such as keratin positivity [cytokeratin (CK)7 and, at times, CK20], CD138 positivity (many carcinomas, not only plasmacytoid urothelial carcinoma, stain positive for CD138), MUM1 and kappa/lambda light chain negativity, E-adherin negativity (conventional and micropapillary types of urothelial carcinoma tend to stain positive for E-cadherin and signet-ring cell carcinomas of the bladder tend to stain negative). In the differential diagnosis of plasmacytoid urothelial carcinoma, plasmacytoma must be considered, and immunostaining characteristics can be helpful in the confirmation of the diagnosis in that p63-positive staining and strong keratin would indicate carcinoma. Kappa and lambda in situ hybridization or immunoperoxidase would identify most plasmacytomas. CD138 positivity is expressed by many carcinomas and is, therefore, not helpful, whereas MUM1 preferentially stains plasmacytoma. Plasmacytoid urothelial carcinoma of the urinary bladder has characteristic plasmacytoid morphological features and immunohistochemical staining is helpful in differentiating this tumour from other differential diagnoses. Plasmacytoid urothelial carcinomas are aggressive variants of urothelial carcinomas of the urinary bladder that have been associated with poor prognosis and death of patients following various treatment options including transurethral resection of bladder tumour and/or radical cystectomy, transurethral resection biopsy and/or cystectomy and/or chemotherapy, transurethral resection of bladder tumour, and chemotherapy and/or radiotherapy. Most patients do not survive post treatment; however, there are reports of survival following treatments that have included combination systemic chemotherapy.