Molecular Characterization of Juxtaglomerular Cell Tumors: Evidence of Alterations in MAPK-RAS Pathway

Juxtaglomerular cell tumor (JGCT) is a rare neoplasm, part of the family of mesenchymal tumors of the kidney. Although the pathophysiological and clinical correlates of JGCT are well known, as these tumors are an important cause of early-onset arterial hypertension refractory to medical treatment, their molecular background is unknown, with only few small studies investigating their karyotype. Herein we describe a multi-institutional cohort of JGCTs diagnosed by experienced genitourinary pathologists, evaluating clinical presentation and outcome, morphologic diversity, and, importantly, the molecular features. Ten JGCTs were collected from 9 institutions, studied by immunohistochemistry, and submitted to whole exome sequencing. Our findings highlight the morphologic heterogeneity of JGCT, which can mimic several kidney tumor entities. Three cases showed concerning histologic features, but the patient course was unremarkable, which suggests that morphologic evaluation alone cannot reliably predict the clinical behavior. Gain-of-function variants in RAS GTPases were detected in JGCTs, with no evidence of additional recurrent genomic alterations. In conclusion, we present the largest series of JGCT characterized by whole exome sequencing, highlighting the putative role of the MAPK-RAS pathway.

Penile squamous cell carcinoma exclusive to the shaft, with a proposal for a novel staging system

Penile squamous cell carcinomas (SCC) originating in the shaft are rare. pT1/pT2 categories in the American Joint Committee on Cancer (AJCC) staging manual (8th edition) are poorly defined for SCCs arising in the dorsal shaft as anatomic structures differ between the glans and dorsal shaft (corpus spongiosum vs dartos/Buck's fascia, respectively). We reviewed six penile SCC cases exclusive to the shaft, an unusual presentation, identified amongst 120 patients treated with penectomy. We propose a novel pT staging system for dorsal shaft tumors tailored to its anatomic landmarks, where tumors extending to Buck's fascia are considered pT2 instead of pT1. The mean age at penectomy, average duration of follow-up, and mean depth of invasion were 64 years, 45 months, and 9.8 mm, respectively. Four cases were moderately differentiated, HPV-negative SCCs of the usual type and two cases were HPV-positive basaloid and warty-basaloid carcinomas. Three cases had nodal or distant metastasis at the time of penectomy, and histologic assessment in these cases showed invasion into the Buck's fascia or deeper. According to the current AJCC system, only one of these three cases would be staged as ≥ pT2. In contrast, all three metastatic tumors would be staged as ≥ pT2 in the proposed model. At last follow-up, one patient died of disease-related complications. Based on this limited series, the proposed staging model appears to suggest better patient stratification for pT1/pT2 stages. This model incorporates Buck's fascia, which has been postulated as a pathway of tumor infiltration. Additional studies are needed to validate this model.

Pathological characterization and clinical outcome of penile intraepithelial neoplasia variants: a North American series

Penile intraepithelial neoplasia (PeIN) is classified as human papillomavirus (HPV)- and non-HPV-related. This classification is associated with distinct morphologic subtypes. The natural history and prognosis of PeIN subtypes are not well known. This study aims to evaluate clinicopathological features, HPV status, and outcome of PeIN subtypes. Eighty-two lesions from 64 patients with isolated PeIN were retrospectively reviewed. Mean age was 59 years. Lesions were multicentric in 34% of patients and affected glans (33%), shaft (26%), and foreskin (20%). Histologically, 22% of patients had coexisting lesions, classified as hybrid and mixed. HPV-related PeIN (97%) included basaloid (59%), warty (8%), warty-basaloid (8%), hybrid (19%) and mixed (3%) types. P16 and HPV positivity occurred in 99% and 82% of lesions, respectively. HPV 16 was more common in basaloid PeIN. Multiple genotypes were detected in 35%, more commonly in hybrid PeIN (P = 0.051). Positive margins occurred in 63% of excisions. PeIN recurred in 48% of excisions and 30% of overall repeated procedures, and progression to invasive carcinoma occurred in 2%. At follow-up, 86% of patients had no evidence of disease and 12% were alive with disease. Lichen sclerosus occurred in non-HPV and HPV-related PeIN (100% and 47%).In conclusion, HPV-related and, more specifically basaloid PeIN were the predominant types and preferentially associated with HPV 16. While PeIN had a high recurrence rate, there was a slow and infrequent progression to invasive or metastatic carcinoma with multimodal treatments. Additional studies are needed to understand biology and natural history of PeIN.

Testicular Germ-Cell Tumors with Spermatic Cord Involvement: A Retrospective International Multi-Institutional Experience

The 8th Edition of the American Joint Committee on Cancer (AJCC) Staging Manual designates discontinuous involvement of spermatic cord soft tissue by testicular germ cell tumors as a metastatic deposit. We conducted a retrospective international multi-institutional study to validate the current recommendations. Thirty-three (72%) nonseminomatous and 13 (28%) seminomatous testicular germ cell tumors were collected from 15 institutions in America, Europe, and Asia. Testicular tumor size ranged from 1.3 to 18.0 cm (mean: 6.1). Cases were classified as discontinuous involvement of spermatic cord soft tissue (n = 26), continuous cord involvement (n = 17), or cord lymphovascular invasion (n = 3). The mean follow-up was 39 months. Clinical stage for discontinuous involvement of spermatic cord soft-tissue patients was I (local disease) in 2/24 (8%), II (regional disease) in 6/24 (25%), and III (distant disease) in 16/24 (67%) cases; 16 (67%) patients presented with distant metastasis. Clinical stage for continuous cord involvement patients was I in 9/17 (53%), II in 4/17 (23%), and III in 4/17 (23%); 4 (23%) patients presented with distant metastasis. Disease progression was seen in 4 patients with discontinuous involvement of spermatic cord soft tissue and 5 with continuous cord-involvement (p = 0.699). When comparing discontinuous and continuous cord involvement, a significant difference was found in cord margin status (p = 0.044), spermatic cord tumor size (p = 0.016), lymph-node involvement (p = 0.037), distant metastasis (p = 0.010), individual clinical stage (p = 0.003), and nonadvanced vs. advanced disease (p = 0.003) at presentation. In multivariate analysis, after adjusting for age, histology, testicular tumor size, percent of embryonal carcinoma, lymphovascular invasion, and cord margin status, discontinuous involvement of spermatic cord soft tissue was significantly associated (p = 0.011) with advanced clinical stage at presentation. Our findings support the designation of metastatic disease for discontinuous involvement of spermatic cord soft tissue, as introduced by the 8th edition of the AJCC staging.

Diagnostic utility of one-stop fusion gene panel to detect TFE3/TFEB gene rearrangement and amplification in renal cell carcinomas

MiT family translocation renal cell carcinoma (MiT-RCC) harbors translocations involving the TFE3 or TFEB genes. RCC with TFEB amplification is also identified and is associated with a more aggressive clinical course. Accurate diagnosis of MiT-RCC is crucial for patient management. In this study, we evaluated the performance of the Archer FusionPlex assay for detection of MiT-RCC with TFE3 or TFEB translocations and TFEB amplifications. RNA was extracted from 49 RCC FFPE tissue samples with known TFE3/TFEB status (26 TFE3 FISH positive, 12 TFEB FISH positive, 4 TFEB amplified (1 case both split and amplified), and 8 FISH negative) using the Covaris extraction kit. Target enriched cDNA libraries were prepared using the Archer FusionPlex kit and sequenced on the Illumina NextSeq 550. We demonstrate that the age of the specimen, quality of RNA, and sequencing metrics are important for fusion detection. Fusions were identified in 20 of 21 cases less than 2 years old, and TFE3/TFEB rearrangements were detected in all cases with Fusion QC ≥ 100. The assay identified intrachromosomal inversions in two cases (TFE3-RBM10 and NONO-TFE3), usually difficult to identify by FISH assays. TFEB mRNA expression and the TFEB/TFE3 mRNA expression ratio were significantly higher in RCCs with TFEB fusion and TFEB gene amplification compared to tumors without TFEB fusion or amplification. A cutoff TFEB/TFE3 ratio of 0.5 resulted in 97.3% concordance to FISH results with no false negatives. Our study demonstrates that the FusionPlex assay successfully identifies TFE3 and TFEB fusions including intrachromosomal inversions. Age of the specimen and certain sequencing metrics are important for successful fusion detection. Furthermore, mRNA expression levels may be used for predicting cases harboring TFEB amplification, thereby streamlining testing. This assay enables accurate molecular detection of multiple subtypes of MiT-RCCs in a convenient workflow.

Well-differentiated neuroendocrine tumors of the lower urinary tract: biologic behavior of a rare entity

The spectrum of neuroendocrine (NE) tumors in the genitourinary tract ranges from the aggressive large and small cell carcinomas to the often benign paraganglioma and well-differentiated neuroendocrine tumor (WD-NET). At least 15 pure lower urinary tract (LUT) WD-NETs have been described. Owing to the rarity of WD-NET in the LUT and the limited number of reported cases, a better definition of their biologic long-term behavior is warranted. Herein, we aim to describe 10 new cases of WD-NET arising in the LUT and expand on follow-up findings. Ten consultation cases were identified and included 6 men and 4 women who ranged from 45 to 73 years of age. Seven cases arose in the bladder with one located in the bladder neck, 1 arose in the prostatic urethra, 1 arose in the female urethra, and 1 arose in the left ureteral orifice. All lesions were confined to the lamina propria, and tumor architecture was pseudoglandular in all cases. Associated cystitis cystica et glandularis was identified in 5 cases; urothelial papilloma and florid von Brunn's nests were found in 2 additional cases. Immunohistochemical staining for synaptophysin and chromogranin was diffusely positive in 9 cases and focal in 1 case, and the Ki-67 proliferation index was 5% or less in all tumors. Follow-up ranged from 37 to 137 months (mean = 82; median = 77), and there was no evidence of residual disease or recurrence in any of the 10 patients during the follow-up period.

Vascular Pattern and Density in Clear Cell vs Clear Cell Papillary Renal Cell Carcinoma

Introduction/Objective

Renal cell carcinomas (RCCs) are well-vascularized tumors. Although clear cell RCC (ccRCC) shows a characteristic vascular network, in some cases may show overlapping features with other RCCs. Microvessel density (MVD) and architectural vascular arrangement in RCC have been characterized using CD31 and CD34 immunohistochemical (IHC) stains. To date, no studies have evaluated the vascular distribution in ccRCC compared to clear cell papillary RCC (ccpRCC). We aimed to identify potential differences in MVD, vascular pattern architecture and extent in ccRCC and ccpRCC.

Methods

Fifteen cases of ccRCC and 15 cases of ccpRCC were included in the study. ERG IHC stain and Bioquant Osteo 2019 Imaging Analysis Software were used to evaluate MVD in 12 cases (6 ccRCC, 6 ccpRCC). CD34 was used to evaluate architectural vascular pattern and its extent (% of tumor) in all cases. Mann–Whitney U test in STATA version 16.0 was used for statistical analysis.

Results

MVD means were 30.64 (CI: 17.9-43.29) in ccRCC and 29.2 (CI: 17.82-40.57) in ccpRCC. CD34 highlighted 4 distinct vascular patterns: lacunae, pseudoacinar, Golgi-like and scattered. The extent of patterns ranged from 0% to 90%. Heterogeneous distribution of different vascular patterns was found in both RCC groups. Although lacunae pattern was present in all RCC cases, pseudoacinar (100.0% vs 31.0%), Golgi-like (53.8% vs 100%) and scattered (53.8% vs 38.0%) patterns showed different distribution in ccRCC vs ccpRCC, respectively. Lacunae+pseudoacinar was the most frequent combination in all ccRCCs; lacunae+Golgi-like was identified in 77% of ccpRCCs. Pseudoacinar was the most extensive pattern in ccRCCs, meanwhile Golgi-like was the predominant pattern in ccpRCCs (p value<0.05).

Conclusion

There was no difference in MVD between ccRCC and ccpRCC. However, the extent of vascular patterns pseudoacinar and Golgi-like was significantly different between ccRCC and ccpRCC. Distinct architectural vascular arrangement could help discriminate these entities.

Mismatch Repair Gene Expression In Testicular Germ Cell Tumors And Retroperitoneal Lymph Node Metastasis

Introduction/Objective

Testicular germ cell tumors (TCGT) with somatic mismatch repair pathway defects have shown to have worse prognosis and response to therapy. Immunohistochemical staining pattern of MMR panel was classified in a previous study as low (absent or minimal) and high staining (moderate or high staining), with the low staining pattern suggestive of poor prognosis and high risk of recurrence. Herein, we studied the MMR staining pattern in TGCT and lymph node metastasis.

Methods

21 TGCT were included in the study: 10 primary testicular tumors and 11 unrelated retroperitoneal lymph node metastasis. All cases were analyzed for MMR protein expression by immunohistochemistry. Clinical, histopathological and follow-up was obtained in all cases. Retained MLH1, MSH2, MSH6, and PMS2 was defined as nuclear staining. Loss of expression was defined as absence of nuclear staining within tumor cells with retained expression in internal control cells, including benign testicular tissue, stromal cells, and infiltrating lymphocytes.

Results

All primary testicular tumors were mixed GCT: embryonal carcinomas was present in 5, yolk sac tumor in 3 and teratoma in 6 cases. One (10%) of the primary tumors showed focal loss of MLH1 and PMS2 expression in a focus of embryonal carcinoma. All lymph node metastases consisted of teratoma. Seven (64%) metastatic cases showed scattered areas of focal MLH1 loss, 5 (45%) of which showed also focal loss of PMS2. High staining for MSH2 and MSH6 was detected in all 21 cases.

Conclusion

In our small cohort, focal loss of MLH1 and PMS2 was detected in 10% of primary TGCT, compared to focal loss of MLH1 and PMS2 is 64% and 45%, respectively, of metastatic tumors, suggesting a possible relationship between heterogeneous MLH1 and PMS2 expression and retroperitoneal lymph node metastasis. The current cohort will be expanded to include additional cases.