I agree, that the appearances are highly suggestive of lymphoma.For a more precise morphologic evaluation, could you please submit several high power images (40x or 63x) from different areas of the tumor. Sometimes it may be difficult to find lymphoepitheloid lesions, and several sections should be examined. Let's wait for the additional high power images.  
Does the patient have other signs suggestive of lymphoma, such as lymphadenopathy, liver, spleen enlargement ? I am asking these questions to rule out secondary involvement by nodal lymphoma.

Thanks for the additional high power images. On high power the cells have quite large and pleomorphic nuclei. Unfortunately they seem to be over stained, therefore no nuclear details can be recognized. Some of the nuclei are surrounded by rather broad rims of cytoplasm. In view of these findings, I have to revise my previous comment. These findings are not compatible with the diagnosis on low grade lymphoma of malt type. This is a poorly differentiated malignant neoplasm DD high grade lymphoma versus a non lymphoid neoplasm.

Thanks very much Prof hurwitz. Also the patient does not have hepato- or splenomegalyu but there were multiple mesenteric and paraaortic lymphadenopathy at operation, according to the surgeon.