Lymphoepithelioma-like carcinoma of the prostate

Abstract

In this report, we summarized the clinicopathologic features of 5 cases of lymphoepithelioma-like carcinoma of the prostate, a rare variant of prostate cancer characterized by a malignant epithelial component densely infiltrated by lymphoid cells. In all 5 patients, there were obstructive symptoms and elevated prostate-specific antigen; one patient had also hematuria. Their ages ranged from 69 to 82 years (mean age, 76 years). The initial diagnosis of lymphoepithelioma-like carcinoma of the prostate was made on transurethral resection in 3 cases and radical prostatectomy in 2 others. In one case the diagnosis of lymphoepithelioma-like carcinoma admixed with conventional acinar adenocarcinoma was an unexpected finding at time of transurethral resection for benign prostatic hyperplasia. Three patients had clinical stage T3 tumors and another had stage T4 disease; stage T1b was present in the remaining case. Microscopically, all tumors contained lymphoepithelioma-like carcinoma, which comprised 10% to 90% of the entire tumor. All cases were associated with adenocarcinoma, either as the sole pattern in 5 cases or with an additional ductal component in 3 cases. One case had additional features of adenosquamous carcinoma. The lymphoepithelioma-like carcinoma component was characterized by indistinct cytoplasmic borders and a syncytial growth pattern. The stroma was densely infiltrated by lymphoid cells admixed with some plasma cells and neutrophils; one case had a prominent infiltration of eosinophils. Immunohistochemical staining demonstrated that lymphoepithelioma-like carcinoma was positive for prostate-specific antigen, prostate acid phosphatase, alpha-methylacyl coenzyme A racemase, and epithelial membrane antigen; several cytokeratins (AE1/AE3, 7, 8, and 20 [rare cells]) were also immunoreactive. The mean Ki-67 labeling index was 53% (range, 40%-70%), and the p53 expression in all cases was low (10%-20%). The lymphoid component was mainly composed of T with a minor subset of B cells, admixed with some dendritic cells and histiocytes as seen by S100 and CD68 immunoreactivity. Latent membrane protein 1 immunostaining and in situ hybridization for Epstein-Barr virus were negative in all 5 lymphoepithelioma-like carcinoma cases. DNA ploidy of lymphoepithelioma-like carcinoma tumors gave DNA histograms with aneuploid peaks. DNA ploidy of the concurrent adenocarcinoma gave DNA aneuploid peaks except in one DNA diploid case. Four patients died of disease from 8 to 26 months; one patient was lost to follow-up. In summary, lymphoepithelioma-like carcinoma of the prostate arise in aggressive prostate cancers at advanced clinical stage. Morphologic recognition and distinction from other prostatic lesions and tumors with prominent lymphoid stroma is critical for its clinical management.