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Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

Eble JN, Sauter G., Epstein JI, Sesterhenn IA - iarc

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1553}. The etiopathogenesis of this<br />

tumour is unknown, although it is suspected<br />

that it originates from modified<br />

urothelial cells, that are possibly derived<br />

from basal (stem) cells {1106}.<br />

Hybridization with <strong>Epstein</strong>-Barr virus<br />

encoded RNA has been reported to be<br />

consistently negative in different series<br />

{82,973,1106,1553}. The tumour is solitary<br />

and usually involves the dome, posterior<br />

wall, or trigone, often with a sessile<br />

growth pattern.<br />

Lymphoepithelioma-like carcinoma may<br />

be pure, predominant or focally admixed<br />

with typical urothelial carcinoma, or in<br />

some cases with squamous cell carcinoma<br />

or adenocarcinoma {1106,1553}. The<br />

proportion of lymphoepithelioma-like carcinoma<br />

histology should be provided in<br />

tumours with mixed histology.<br />

Histologically, the tumour is composed of<br />

nests, sheets, and cords of undifferentiated<br />

cells with large pleomorphic nuclei<br />

and prominent nucleoli. The cytoplasmic<br />

borders are poorly defined imparting a<br />

syncytial appearance. The background<br />

consists of a prominent lymphoid stroma<br />

that includes T and B lymphocytes, plasma<br />

cells, histiocytes, and occasional<br />

neutrophils or eosinophils, the latter<br />

being prominent in rare cases.<br />

Carcinoma in situ elsewhere in the bladder<br />

is rarely present.<br />

The epithelial cells of this tumour stain with<br />

several cytokeratin (CK) markers as follows:<br />

AE1/AE3, CK8, CK 7, and they are<br />

rarely positive for CK20 {1106,1553}. In<br />

some cases, it is possible to overlook the<br />

malignant cells in the background of<br />

inflamed bladder wall and misdiagnose the<br />

condition as florid chronic cystitis {1553}.<br />

The major differential diagnostic considerations<br />

are poorly differentiated urothelial<br />

carcinoma with lymphoid stroma;<br />

poorly differentiated squamous cell carcinoma,<br />

and lymphoma {1553}. The<br />

presence of recognizable urothelial or<br />

squamous cell carcinoma does not<br />

exclude lymphoepithelioma-like carcinoma;<br />

rather, the diagnosis is based on<br />

finding areas typical of lymphoepithelioma-like<br />

carcinoma reminiscent of that<br />

in the nasopharynx. Differentiation from<br />

lymphoma may be difficult, but the presence<br />

of a syncytial pattern of large malignant<br />

cells with a dense polymorphous<br />

lymphoid background is an important<br />

clue {1553}.<br />

Most reported cases of the urinary bladder<br />

had a relatively favourable prognosis<br />

A<br />

B<br />

Fig. 2.14 Lymphoepithelioma-like carcinoma of the urinary bladder. A Characteristic syncytial appearance<br />

of neoplastic cells (H&E). B Note the characteristic immunostaining with CK.<br />

when pure or predominant, but when<br />

lymphoepithelioma-like carcinoma is<br />

focally present in an otherwise typical<br />

urothelial carcinoma, these patients<br />

behave like patients with conventional<br />

urothelial carcinoma alone of the same<br />

grade and stage {1106,1553}. Some<br />

examples of lymphoepithelioma-like carcinoma<br />

have been described in the<br />

ureter and the renal pelvis {820,2224}.<br />

This tumour, thus far has been found to<br />

be responsive to chemotherapy when it<br />

is encountered in its pure form {82,623}.<br />

Experience at one institution has shown a<br />

complete response to chemotherapy and<br />

transurethral resection of the bladder<br />

{82,623}. Another series of nine patients<br />

treated with a combination of transurethral<br />

resection, partial or complete<br />

cystectomy, and radiotherapy disclosed<br />

four patients without evidence of disease,<br />

three who died of their disease and<br />

two who died of other causes {1106}.<br />

Lymphoma-like and plasmacytoid<br />

variants<br />

The lymphoma-like and plasmacytoid<br />

variants of urothelial carcinoma are those<br />

in which the malignant cells resemble<br />

those of malignant lymphoma or plasmacytoma<br />

{1618,2272,2571,2933,2949}.<br />

Less than 10 cases have been reported.<br />

The histologic features of the lymphomalike<br />

and plasmacytoid variants of urothelial<br />

carcinoma are characterized by the<br />

presence of single malignant cells in a<br />

loose or myxoid stroma. The tumour cells<br />

have clear or eosinophilic cytoplasm and<br />

eccentrically placed, enlarged hyperchromatic<br />

nuclei with small nucleoli.<br />

Almost all of the reported cases have had<br />

a component of high grade urothelial carcinoma<br />

in addition to the single malignant<br />

cells. In some of the cases, the single-cell<br />

component was predominant on the initial<br />

biopsy, leading to the differential diagnosis<br />

of lymphoma/plasmacytoma. The<br />

tumour cells stain with cytokeratin (CK)<br />

cocktail, CK 7 and (in some cases) CK 20<br />

{2571}. Immunohistochemical stains for<br />

lymphoid markers have consistently been<br />

reported as negative.<br />

Each of these variants of urothelial carcinoma<br />

may cause a significant differential<br />

diagnostic dilemma, especially in cases<br />

in which it constitutes the predominant or<br />

Infiltrating urothelial carcinoma 101

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