MiT translocation renal cell carcinomas: two subgroups of tumours with translocations involving 6p21 [t (6; 11)] and Xp11.2 [t (X;1 or X or 17)]

Tumors masquerading as type 2 papillary renal cell carcinoma: pathologists' ever-expanding differential diagnosis for a heterogeneous group of entities

Although papillary renal cell carcinoma has historically been classified as either type 1 or type 2, data from The Cancer Genome Atlas (TCGA) has demonstrated significant genomic heterogeneity in tumors classified as "type 2 papillary renal cell carcinoma" (T2PRCC). Papillary renal cell carcinoma is expected to have a favorable clinical course compared to clear cell renal cell carcinoma (CCRCC). However, tumors with poor outcome more similar to CCRCC were included in the T2PRCC cohort studied by the TCGA. The differential diagnosis for T2PRCC includes a variety of other renal tumors, including aggressive entities such as TFE3 translocation-associated renal cell carcinoma, TFEB-amplified renal cell carcinoma, fumarate hydratase-deficient renal cell carcinoma, high-grade CCRCC, and collecting duct carcinoma. Accurate classification of these tumors is important for prognostication and selection of therapy.

6p.21 translocation renal cell carcinoma in the elderly: radiological findings mimicking fat poor angiomyolipoma or papillary renal cell carcinoma

6p21 translocation renal cell carcinoma (RCC) harboring TFEB gene fusion is a newly classified microphthalmia-associated transcription (MiT) factor-family translocation RCC with early onset. We present a case of 78-year-old man with a 6p21 translocation RCC that was diagnosed after partial nephrectomy for an incidental renal tumor on computed tomography (CT). Unenhanced CT showed a 20 mm, mildly low-density mass in the right kidney. Contrast-enhanced CT showed a heterogeneous and prolonged, mild enhancement in the tumor. On magnetic resonance imaging, the tumor showed iso-intensity within the renal parenchyma on T1-weighted-imaging (WI), low intensity on T2WI, and no restricted diffusion with low signal on diffusion-weighted imaging, with no clear tumor pseudocapsule. Fat poor angiomyolipoma and non-clear cell RCC were listed as differential diagnoses. Robot-assisted partial nephrectomy was successfully performed. Fluorescence in situ hybridization study of the resected tumor confirmed TFEB gene break, and the patient was diagnosed with a 6p21 translocation RCC. The patient is doing well without recurrence after 2.5 years of follow-up. Our patient is the oldest patient reported in previous literature.

Percutaneous radiofrequency ablation on a Xp11.2 Translocation Renal Cell Carcinoma: A case report

Xp11.2 Translocation Renal Cell Carcinoma is a very rare subtype of renal neoplasm. The present report describes the first confirmed reported case of percutaneous ablation of this subtype of tumor. The patient presented an aggressive local recurrence 12 months after the procedure, with an infiltrative large mass occupying almost the whole kidney. The patient was submitted to radical nephrectomy. As the use of ablative methods expands, the treatment of rare renal tumor subtypes, which can present unusual clinical outcomes, may become more frequent. It is essential that these uncommon outcomes are promptly recognized, allowing early therapeutic salvage approaches.

TFEB Expression Profiling in Renal Cell Carcinomas: Clinicopathologic Correlations

TFEB is overexpressed in TFEB-rearranged renal cell carcinomas as well as in renal tumors with amplifications of TFEB at 6p21.1. As recent literature suggests that renal tumors with 6p21.1 amplification behave more aggressively than those with rearrangements of TFEB, we compared relative TFEB gene expression in these tumors. This study included 37 TFEB-altered tumors: 15 6p21.1-amplified and 22 TFEB-rearranged (including 5 cases from The Cancer Genome Atlas data set). TFEB status was verified using a combination of fluorescent in situ hybridization (n=27) or comprehensive molecular profiling (n=13) and digital droplet polymerase chain reaction was used to quantify TFEB mRNA expression in 6p21.1-amplified (n=9) and TFEB-rearranged renal tumors (n=19). These results were correlated with TFEB immunohistochemistry. TFEB-altered tumors had higher TFEB expression when normalized to B2M (mean: 168.9%, n=28), compared with non-TFEB-altered controls (mean: 7%, n=18, P=0.005). Interestingly, TFEB expression in tumors with rearrangements (mean: 224.7%, n=19) was higher compared with 6p21.1-amplified tumors (mean: 51.2%, n=9; P=0.06). Of note, classic biphasic morphology was only seen in TFEB-rearranged tumors and when present correlated with 6.8-fold higher TFEB expression (P=0.00004). Our results suggest that 6p21.1 amplified renal tumors show increased TFEB gene expression but not as much as t(6;11) renal tumors. These findings correlate with the less consistent/diffuse expression of downstream markers of TFEB activation (cathepsin K, melan A, HMB45) seen in the amplified neoplasms. This suggests that the aggressive biological behavior of 6p21.1 amplified renal tumors might be secondary to other genes at the 6p21.1 locus that are co-amplified, such as VEGFA and CCND3, or other genetic alterations.

Oncologic outcomes of nephron-sparing surgery in patients with T1 multifocal renal cell carcinoma

OBJECTIVE

This study is performed to explore the pathological characteristics and oncologic outcomes of T1 multifocal renal cell carcinoma (RCC).

METHODS

The clinical data of 600 patients (442 males and 158 females) between the age of 29 and 73 years, diagnosed with T1 RCC were collected from three hospitals in China, out of which 421 cases had undergone nephron-sparing surgery (NSS) and 179 cases had undergone radical nephrectomy (RN) between December 2010 and January 2015.

RESULTS

Tumor was identified with multifocality in 32 patients (5.33%), out of which 21 were set to receive NSS, and 11 to receive RN, respectively; 21 cases of clear cell tumor, 8 cases of papillary tumor, 1 case of chromophobe tumor and 2 cases of Xp.11.2 translocation RCC. Among 568 cases of monofocal tumors, 400 patients underwent NSS, and the remaining 168 patients underwent RN, respectively. After a median follow-up of 5 years, 13 patients were found with recurrent tumors out of those who had undergone NSS, 11 with monofocal tumors and 2 with multifocal tumors containing satellite tumor nodules (p = 0.13). Out of the 32 individuals with multifocal RCC, 4 cases were reported to have died of cancer, 2 of NSS and 2 of RN. From these findings, the cancer-specific survival for NSS and RN was estimated to be 90.48% and 81.82%, respectively (p = 0.48).

CONCLUSION

The findings from the study suggested that there were pathological differences in multifocal renal tumors, and that papillary carcinoma may be more common than clear cell carcinoma. The recurrence rate and survival rate of multifocal RCC were similar to monofocal tumors. Tumor recurrence may be related to satellite tumor nodules, which can only be detected once surgery is performed.

Detection of 6 TFEB-amplified renal cell carcinomas and 25 renal cell carcinomas with MITF translocations: systematic morphologic analysis of 85 cases evaluated by clinical TFE3 and TFEB FISH assays

Renal cell carcinomas with MITF aberrations demonstrate a wide morphologic spectrum, highlighting the need to consider these entities within the differential diagnosis of renal tumors encountered in clinical practice. Herein, we describe our experience with application of clinical fluorescence in situ hybridization (FISH) assays for detection of TFE3 and TFEB gene aberrations from 85 consecutive renal cell carcinoma cases submitted to our genitourinary FISH service. Results from 170 FISH assays performed on these tumors were correlated with available clinicopathologic findings. Ninety-eight percent of renal tumors submitted for FISH evaluation were from adult patients. Thirty-one (37%) tumors were confirmed to demonstrate MITF aberrations (21 TFE3 translocation, 4 TFEB translocation, and 6 TFEB amplification cases). Overall, renal cell carcinomas with MITF aberrations demonstrated morphologic features overlapping with clear cell, papillary, or clear cell papillary renal cell carcinomas. Renal cell carcinomas with MITF aberrations were significantly more likely to demonstrate dual (eosinophilic and clear) cytoplasmic tones (P=0.030), biphasic TFEB translocation renal cell carcinoma-like morphology (P=0.002), psammomatous calcifications (P=0.002), and nuclear pseudoinclusions (P=0.001) than renal cell carcinomas without MITF aberrations. Notably, 7/9 (78%) renal cell carcinomas exhibiting subnuclear clearing and linear nuclear array (6 of which showed high World Health Organization/International Society of Urological Pathology nucleolar grade) demonstrated TFE3 translocation, an association that was statistically significant when compared with renal cell carcinomas without MITF aberrations (P=0.009). In this cohort comprising consecutive cases, TFEB-amplified renal cell carcinomas were more commonly identified than renal cell carcinomas with TFEB translocations, and four (67%) of these previously unreported TFEB-amplified renal cell carcinomas demonstrated oncocytic and papillary features with a high World Health Organization/International Society of Urological Pathology nucleolar grade. In summary, TFE3 and TFEB FISH evaluation aids in identification and accurate classification of renal cell carcinomas with MITF aberrations, including TFEB-amplified renal cell carcinoma, which may demonstrate aggressive behavior.