Is Tubulocystic Renal Cell Carcinoma Real?: Genomic Analysis Confirms the World Health Organization Classification

Tubulocystic renal cell carcinoma: Two-case report and literature review

Tubulocystic renal cell carcinoma is a rare neoplasm of kidney with low metastatic tendency. There has only been a relatively small collection of literature dedicated to this subtype. Here we present two cases diagnosed in our center with detailed clinical information. Along with literature review, we aim to paint a comprehensive profile of TC-RCC. Hematuria and asthenia could be the chief complaints although most patients are asymptomatic. This lesion has a signature multilocular cystic form on radiology and enhancement of septa should reveal malignancy. Histologically, the cysts are lined by a single layer of flattened, cuboidal/columnar, and hobnail epithelium with enlarged nuclei and intermediate to large nucleoli. PAX8 and AMACR are most commonly positive while CD10 or CK7 could be focally stained in some cases. Overall, the diagnosis of TC-RCC should be based on comprehensive clinical and molecular results because early determination of the lesion could prelude a timely intervention and favorable prognosis.

Identification of RCC Subtype-Specific microRNAs-Meta-Analysis of High-Throughput RCC Tumor microRNA Expression Data

Renal cell carcinoma (RCC) is one of the most common cancers worldwide with a nearly non-symptomatic course until the advanced stages of the disease. RCC can be distinguished into three subtypes: papillary (pRCC), chromophobe (chRCC) and clear cell renal cell carcinoma (ccRCC) representing up to 75% of all RCC cases. Detection and RCC monitoring tools are limited to standard imaging techniques, in combination with non-RCC specific morphological and biochemical read-outs. RCC subtype identification relays mainly on results of pathological examination of tumor slides. Molecular, clinically applicable and ideally non-invasive tools aiding RCC management are still non-existent, although molecular characterization of RCC is relatively advanced. Hence, many research efforts concentrate on the identification of molecular markers that will assist with RCC sub-classification and monitoring. Due to stability and tissue-specificity miRNAs are promising candidates for such biomarkers. Here, we performed a meta-analysis study, utilized seven NGS and seven microarray RCC studies in order to identify subtype-specific expression of miRNAs. We concentrated on potentially oncocytoma-specific miRNAs (miRNA-424-5p, miRNA-146b-5p, miRNA-183-5p, miRNA-218-5p), pRCC-specific (miRNA-127-3p, miRNA-139-5p) and ccRCC-specific miRNAs (miRNA-200c-3p, miRNA-362-5p, miRNA-363-3p and miRNA-204-5p, 21-5p, miRNA-224-5p, miRNA-155-5p, miRNA-210-3p) and validated their expression in an independent sample set. Additionally, we found ccRCC-specific miRNAs to be differentially expressed in ccRCC tumor according to Fuhrman grades and identified alterations in their isoform composition in tumor tissue. Our results revealed that changes in the expression of selected miRNA might be potentially utilized as a tool aiding ccRCC subclass discrimination and we propose a miRNA panel aiding RCC subtype distinction.