Lymphoepithelioma-like carcinoma of the urinary bladder: clinicopathologic, immunohistochemical, and molecular features.

INTRODUCTION: Lymphoepithelioma-like carcinoma (LELC) in the urinary tract is a rare malignancy, named for its resemblance to nasopharyngeal undifferentiated carcinoma or lymphoepithelioma. Investigation of immunohistochemical and molecular characteristics of bladder LELC is limited. The pathogenesis and biological behavior of these tumors are controversial.
MATERIALS AND METHODS: We examined clinicopathologic features of the urinary tract LELC, including light microscopy; immunohistochemistry for cytokeratin 7 (CK7), CK20, 34βE12, p53, p63, α-methylacyl-CoA racemase, thyroid transcription factor-1, Epstein-Barr virus latent membrane protein-1, and CD30; in situ hybridization for human papillomavirus; and UroVysion fluorescence in situ hybridization (FISH).
RESULTS: We identified tumors from 34 patients, the largest series to date, (male:female, 2.8:1), ranging from 54 to 84 years of age (mean, 70 years). Urothelial carcinoma in situ was identified in 50% of patients. 34βE12 (75%), CK7 (57%), and p63 (53%) were frequently positive in tumor cells, whereas thyroid transcription factor-1 and CD30 were consistently negative. Expression of p53 was noted in a subset of tumors (61%), whereas CK20 staining was negative with weak positivity in a single case. UroVysion FISH showed frequent chromosomal abnormalities similar to those of urothelial carcinoma. In tumors with concurrent urothelial, squamous, sarcomatoid, and glandular components, identical FISH abnormalities were noted in both areas. In situ hybridization for human papillomavirus and immunostaining for Epstein-Barr virus were negative in all studied lesions. Five patients with pure or predominant LELC tumors treated with transurethral resection and followed by chemotherapy were alive without evidence of disease at 2 to 5 years. In contrast, 2 patients treated in this manner with <50% LELC morphology had death from disease or distant metastasis. DISCUSSION: Urinary tract LELC is a rare histologic variant of urothelial carcinoma. The frequent presence of UroVysion FISH abnormalities, urothelial carcinoma in situ, and p53 positivity by immunohistochemistry in cases of urinary tract LELC suggests a similar pathogenesis to high-grade invasive urothelial carcinoma. In contrast to typical urothelial carcinoma, CK20 is frequently negative in LELC. Our findings support the hypothesis that pure or predominant LELC may be treated with transurethral resection and chemotherapy. However, a large-scale study with long-term follow-up is needed to better understand the biological behavior of urinary bladder LELC.