Human papilloma virus (HPV) DNA has been shown in the tumor cells of lymphoepitheliomas of the breast, (25) and transcriptionally active HPV has been shown by in situ hybridization in LELCs of the oropharynx.
The presence of HPV has been shown in the LELCs of other organs, such as oral cavity, (26,27) breast, (25) and uterine cervix.
The prominent lymphoid background in the tumour presents a challenge for the pathologists in distinguishing LELC from inflammatory lesions such as xanthogranulomatous pyelonephritis.
Immunohistochemistry helps in the distinction of LELC from lymphomas, since the treatment regimens, prognostic factors and survival rates vary among these tumours.
The gross appearance of the tumor also can give some clues as the LELC will be firm to rubbery in consistency (akin to lymphoma or tumors with lymphoid infiltrate) with less of necrosis and haemorrhage.
The exact etiology and pathogenesis of LELC involving the kidney and the urinary system is unknown.
The World Health Organization's classification of urinary tract tumours describes LELC as a subgroup of urothelial carcinoma because it is derived from modified urothelial cells.
Amin and colleagues classified LELC of the urinary bladder into 3 categories: pure (100% LELC), predominant (more than 50% LELC) and focal (less than 50% LELC).
Unlike nasopharyngeal lymphoepithelioma, LELC of the urinary tract is not associated with the Epstein-Barr virus (EBV) on immunohistochemical analysis.
On biopsy specimens, which could be crushed or inadequately fixed, differential diagnosis of LELC includes small cell carcinoma of the bladder.
Lastly, an undifferentiated transitional cell carcinoma with lymphoid reaction has to be distinguished from LELC with the typical cytologic features and syncytial pattern of the tumor cells.
The best reason to recognize LELC pattern is the favorable outcome of this histologic subtype, especially the pure or the predominate pattern.