ERG rearrangements, (most commonly TMPRSS2: ERG [T2:ERG] gene fusions), have been identified in approximately 50% of prostate cancers (PCa). Quantification of T2:ERG in post-DRE urine, in combination with PCA3, improves the performance of serum PSA for PCa prediction on biopsy Here we compared urine T2:ERG and PCA3 scores to ERG+ (determined by immunohistochemistry) and total prostate cancer burden in 41 mapped prostatectomies. Prostatectomies had a median of 3 tumor foci (range: 1–15) and 2.6 cm of summed linear tumor dimension (range: 0.6–7.1 cm). Urine T2:ERG score most correlated with summed linear ERG+ tumor dimension and number of ERG+ foci (rs=0.68 and 0.67, respectively, both p<0.001). Urine PCA3 score showed weaker correlation with both number of tumor foci (rs=0.34, p=0.03) and summed linear tumor dimension (rs=0.26, p=0.10). In summary, we demonstrate a strong correlation between urine T2:ERG score and total ERG+ PCa burden at prostatectomy, consistent with high tumor specificity.

PCA3 is a prostate-specific non-coding RNA, with utility as urine based early detection biomarker. Here, we report the evaluation of tissue PCA3 expression by RNA in-situ hybridization in a cohort of 41 mapped prostatectomy specimens. We compared tissue PCA3 expression with tissue level ERG expression and matched pre-prostatectomy urine PCA3 and TMPRSS2-ERG levels. Across 136 slides containing 138 foci of prostate cancer, PCA3 was expressed in 55% of cancer foci and 71% of high grade prostatic intraepithelial neoplasia foci. Overall, the specificity of tissue PCA3 was >90% for prostate cancer and high grade prostatic intraepithelial neoplasia combined. Tissue PCA3 cancer expression was not significantly associated with urine PCA3 expression. PCA3 and ERG positivity in cancer foci were positively associated (p<0.01). We report the first comprehensive assessment of PCA3 expression in prostatectomy specimens, and find limited correlation between tissue PCA3 and matched urine in prostate cancer.

We report the case of a high-grade carcinoma involving the kidney in a young male with renal vein thrombosis and review the differential diagnosis and immunohistochemical workup. High-grade neoplasms involving the renal sinus include collecting duct carcinomas (CDCs), renal medullary carcinomas (RMCs), invasive high-grade urothelial carcinoma (UC) of the upper urinary tract, clear cell renal cell carcinoma, and type 2 papillary renal cell carcinoma. Distinguishing UC from CDC and RMC is problematic in small biopsy samples. The diagnosis of CDC (a rare, aggressive subtype of renal cell carcinoma) is challenging and requires the exclusion of UC. Renal medullary carcinoma is characterized by an appropriate clinical setting and consistent loss of nuclear expression of integrase interactor 1 (INI-1). A panel consisting of p63, paired box gene 8 (PAX8), and INI-1 is most optimal in distinguishing UC from CDC and RMC. A subset of urothelial carcinoma of upper urinary tract may be positive with PAX8.

Schwannomas originating in the kidney are extremely rare with very few cases documented in the literature. It is difficult to distinguish them from other common renal masses based on clinical symptoms and imaging characteristics alone, as both are non-specific for this pathology. Thus, the final diagnosis of schwannoma is typically made only after surgical resection and histologic examination. We present the case of a 66-year-old female who was initially evaluated for flank pain and referred to us after a renal mass was found on CT imaging. A partial nephrectomy was performed, and subsequent pathological examination confirmed the diagnosis of renal schwannoma.