L1 Cell Adhesion Molecule (L1CAM) Expression and Molecular Alterations Distinguish Low-Grade Oncocytic Tumor From Eosinophilic Chromophobe Renal Cell Carcinoma.

Renal low-grade oncocytic tumor (LOT) is a recently recognized renal cell neoplasm designated within the "other oncocytic tumors" category in the 2022 World Health Organization classification system. Although the clinicopathologic, immunohistochemical, and molecular features reported for LOT have been largely consistent, the data are relatively limited. The morphologic overlap between LOT and other low-grade oncocytic neoplasms, particularly eosinophilic chromophobe renal cell carcinoma (E-chRCC), remains a controversial area in renal tumor classification. To address this uncertainty, we characterized and compared large cohorts of LOT (n = 67) and E-chRCC (n = 69) and revealed notable differences between the 2 entities. Clinically, LOT predominantly affected women, whereas E-chRCC showed a male predilection. Histologically, although almost all LOTs were dominated by a small-nested pattern, E-chRCC mainly showed solid and tubular architectures. Molecular analysis revealed that 87% of LOT cases harbored mutations in the tuberous sclerosis complex (TSC)-mTOR complex 1 (mTORC1) pathway, most frequently in MTOR and RHEB genes; a subset of LOT cases had chromosomal 7 and 19q gains. In contrast, E-chRCC lacked mTORC1 mutations, and 60% of cases displayed chromosomal losses characteristic of chRCC. We also explored the cell of origin for LOT and identified L1 cell adhesion molecule (L1CAM), a collecting duct and connecting tubule principal cell marker, as a highly sensitive and specific ancillary test for differentiating LOT from E-chRCC. This distinctive L1CAM immunohistochemical labeling suggests the principal cells as the cell of origin for LOT, unlike the intercalated cell origin of E-chRCC and oncocytoma. The ultrastructural analysis of LOT showed normal-appearing mitochondria and intracytoplasmic lumina with microvilli, different from what has been described for chRCC. Our study further supports LOT as a unique entity with a benign clinical course. Based on the likely cell of origin and its clinicopathologic characteristics, we propose that changing the nomenclature of LOT to "Oncocytic Principal Cell Adenoma of the Kidney" may be a better way to define and describe this entity.

Differential NEUROD1, ASCL1, and POU2F3 Expression Defines Molecular Subsets of Bladder Small Cell/Neuroendocrine Carcinoma with Prognostic Implications.

Small cell carcinomas (SMC) of the lung are now molecularly classified based on the expression of transcriptional regulators (NEUROD1, ASCL1, POU2F3, YAP1) and DLL3, which has emerged as an investigational therapeutic target. PLCG2 has been shown to identify a distinct subpopulation of lung SMC with stem cell-like and pro-metastasis features and poor prognosis. We analyzed the expression of these novel neuroendocrine markers and their association with traditional neuroendocrine markers and patient outcomes in a cohort of bladder neuroendocrine carcinoma (NEC) consisting of 103 SMC and 19 large cell neuroendocrine carcinomas (LCNEC) assembled in tissue microarrays. Co-expression patterns were assessed and integrated with detailed clinical annotation including overall (OS) and recurrence free survival (RFS) and response to neoadjuvant/adjuvant chemotherapy. We identified five distinct molecular subtypes in bladder SMC based on expression of ASCL1, NEUROD1 and POU2F3: ASCL1+/NEUROD1- (n=33; 34%), ASCL1-/NEUROD1+ (n=21; 21%), ASCL1+/NEUROD1+ (n=17; 17%), POU2F3+ (n=22, 22%), and ASCL1-/NEUROD1-/POU2F3- (n=5, 5%). POU2F3+ tumors were mutually exclusive with those expressing ASCL1 and NEUROD1 and exhibited lower expression of traditional neuroendocrine markers. PLCG2 expression was noted in 33 tumors (32%) and was highly correlated with POU2F3 expression (p < 0.001). DLL3 expression was high in both SMC (n=72, 82%) and LCNEC (n=11, 85%). YAP1 expression was enriched in non- neuroendocrine components and negatively correlated with all neuroendocrine markers. In patients without metastatic disease who underwent radical cystectomy, PLCG2+ or POU2F3+ tumors had shorter RFS and OS (p<0.05), but their expression was not associated with metastasis status or response to neoadjuvant/adjuvant chemotherapy. In conclusion, NEC of the bladder can be divided into distinct molecular subtypes based on the expression of ASCL1, NEUROD1 and POU2F3. POU2F3 expressing tumors represent an ASCL1/NEUROD1-negative subset of bladder NEC characterized by lower expression of traditional neuroendocrine markers. Marker expression patterns were similar in SMC and LCNEC. Expression of PLCG2 and POU2F3 was associated with shorter recurrence-free and overall survival. DLL3 was expressed at high levels in both SMC and LCNEC of the bladder, nominating it as a potential therapeutic target.

Update on Selected High-grade Renal Cell Carcinomas of the Kidney: FH-deficient, ALK-rearranged, and Medullary Carcinomas.

High-grade renal cell carcinoma (RCC), often diagnosed at advanced stages, significantly contributes to renal cancer-related mortality. This review explores the progress in understanding specific subtypes of high-grade RCC, namely fumarate hydratase (FH)-deficient RCC, anaplastic lymphoma kinase (ALK)-rearranged RCC, and SMARCB1-deficient renal medullary carcinoma, all of which are now recognized as molecularly defined entities in the WHO classification system (2022). While these entities each exhibit a morphologic spectrum that overlaps with other high-grade RCC, ancillary tools developed based on their distinctive molecular alterations can help establish a specific diagnosis, underscoring the importance of integrating molecular findings into diagnostic paradigms. It is important to exclude these specific tumor types in cases with similar morphologic spectrum before rendering a diagnosis of high-grade papillary RCC, collecting duct carcinoma, or RCC, NOS. Several gray areas exist within the spectrum of high-grade uncommon types of RCC, necessitating continued research to enhance diagnostic precision and therapeutic options.

Neurofibromatosis Type 2-Yes-Associated Protein and Transcriptional Coactivator With PDZ-Binding Motif Dual Immunohistochemistry Is a Reliable Marker for the Detection of Neurofibromatosis Type 2 Alterations in Diffuse Pleural Mesothelioma.

Neurofibromatosis type 2 (NF2) loss occurs in approximately 30% to 50% of diffuse pleural mesothelioma (DPM) with accumulation of yes-associated protein (YAP) 1 and transcriptional coactivator with PDZ-binding motif (TAZ) in tumor nuclei. NF2 and YAP/TAZ represent potential therapeutic targets. We investigated the performance of NF2-YAP/TAZ dual immunohistochemistry (IHC) in identifying DPM that harbors NF2 alterations and in distinguishing DPM from benign mesothelial proliferations. NF2-YAP/TAZ IHC was subsequently performed in a Discovery cohort of DPMs with (n = 10) or without (n = 10) NF2 alterations detected by next-generation sequencing (NGS) and 9 benign cases. The cutoff values for loss of NF2 expression and YAP/TAZ overexpression using IHC were determined in the Discovery cohort. The performance characteristics of NF2-YAP/TAZ IHC were investigated in a Validation cohort (20 DPMs and 10 benign cases). In the Discovery cohort, all DPMs with NF2 alterations using NGS showed NF2 IHC scores of <2, whereas all NF2-wild-type DPMs showed scores of ≥2. NF2-altered DPMs had significantly higher YAP/TAZ H-scores (P < .001) than NF2-wild-type DPM and benign pleura (median H-scores: 237.5 [range, 185-275], 130.0 [range, 40-225], and 10.0 [range, 0-75], respectively). NF2-YAP/TAZ IHC demonstrated 95.2% sensitivity, 100% specificity, 100% positive predictive value, and 95% negative predictive value for detecting NF2 alterations in DPM (n = 40) with NGS as the gold standard and 87.5% sensitivity and 100% specificity for distinguishing DPM (n = 40) from benign mesothelial proliferations (n = 19). NF2-YAP/TAZ IHC has a high sensitivity and specificity for detecting NF2 alterations in DPM and a high specificity for malignancy, highlighting potential utility for guiding NF2-targeted therapies and distinguishing DPM from benign mimics.

Papillary renal cell carcinoma: a single institutional study of 199 cases addressing classification, clinicopathologic and molecular features, and treatment outcome.

The morphologic spectrum of type 1 papillary renal cell carcinoma (PRCC) is not well-defined, since a significant proportion of cases have mixed type 1 and 2 histology. We analyzed 199 cases of PRCC with any (even if focal) type 1 features, with a median follow-up of 12 years, to identify clinicopathological features associated with outcome. Ninety-five tumors (48%) of the cohort contained some type 2 component (median amount: 25%; IQR: 10%, 70%). As a group they showed high rates of progression-free (PFS) and cancer-specific survival (CSS). Tumor size, mitotic rate, lymphovascular invasion, sarcomatoid differentiation, sheet-like architecture, and lack of tumor circumscription were significantly associated with CSS (p ≤ 0.015) on univariate analysis. While predominant WHO/ISUP nucleolar grade was associated with PFS (p = 0.013) and CSS (p = 0.030), the presence of non-predominant (<50%) nucleolar grade did not show association with outcome (p = 0.7). PFS and CSS showed no significant association with the presence or the amount of type 2 morphology. We compared the molecular alterations in paired type 1 and type 2 areas in a subset of 22 cases with mixed type 1 and 2 features and identified 12 recurrently mutated genes including TERT, ARID1A, KDM6A, KMT2D, NFE2L2, MET, APC, and TP53. Among 78 detected somatic mutations, 61 (78%) were shared between the paired type 1 and type 2 areas. Copy number alterations, including chromosome 7 and 17 gains, were similar between type 1 and 2 areas. These findings support that type 2 features in a PRCC with mixed histology represent either morphologic variance or clonal evolution. Our study underscores the notion that PRCC with any classic type 1 regions is best considered as type 1 PRCC and assigned the appropriate WHO/ISUP nucleolar grade. It provides additional evidence that type 2 PRCC as a separate category should be re-assessed and likely needs to be abandoned.

Neuroendocrine differentiation in the setting of prostatic carcinoma: contemporary assessment of a consecutive series.

AIM: Clinicopathologic characterisation of a contemporary series of neuroendocrine (NE) differentiation in the setting of prostatic carcinoma (PCa) was examined. METHODS AND RESULTS: We reviewed institutional databases for in-house cases with a history of PCa and histopathologic evidence of NE differentiation during the disease course. In all, 79 cases were identified: 32 primary and 47 metastases. Metastatic lesions were in liver (n = 15), lymph node (n = 9), bone (n = 6), lung (n = 3), brain (n = 1), and other sites (n = 13). In all, 63 of 76 (82%) cases with NE differentiation and available history were posttherapy: six postradiation therapy (RT), 24 post- androgen-deprivation therapy (ADT), and 33 post-RT + ADT. Morphologic assessment (n = 79): (i) 23 pure small-cell/high-grade NE carcinoma (HGNEC): 20/23 metastatic; (ii) 10 combined high-grade PCa and small-cell/HGNEC: 9/10 primary; (iii) 15 PCa with diffuse NE immunohistochemistry (IHC) marker positivity/differentiation, associated with nested to sheet-like growth of cells with abundant cytoplasm and prominent nucleoli, yet diffuse positivity for at least one prostatic and one NE IHC marker: all metastatic; (iv) 11 PCa with patchy NE differentiation, displaying more than single-cell positivity for NE IHC: five primary / six metastatic; (v) nine PCa with focal NE marker positive cells: four primary / five metastatic; (vi) 11 PCa with 'Paneth cell-like' change: all primary. CONCLUSIONS: In this contemporary series, the majority of NE differentiation in the setting of PCa was seen posttherapy. We highlight the tendencies of small-cell/HGNEC and PCa with diffuse NE differentiation by IHC to occur in metastatic settings, while morphologically combined high-grade PCa + small-cell/HGNEC and 'Paneth cell-like' change occur in primary disease.

Clinical utility of subclassifying positive surgical margins at radical prostatectomy.

OBJECTIVE: To determine whether subclassification of positive surgical margins (PSMs) increases predictive ability for biochemical recurrence (BCR) and aids clinical decision-making in patients undergoing radical prostatectomy. PATIENTS AND METHODS: We studied 2147 patients with pT2 and pT3a prostate cancer with detailed surgical margin parameters and BCR status. We compared a base model, a linear predictor calculated from the Memorial Sloan Kettering Cancer Center postoperative nomogram (prostate-specific antigen, pathological tumour grade and stage), with the addition of surgical margin status to five additional models (base model plus surgical margin subclassifications) to evaluate enhancement in predictive accuracy. Decision curve analysis (DCA) was performed to determine the clinical utility of parameters that enhanced predictive accuracy. RESULTS: Among 2147 men, 205 had PSMs, and 231 developed BCR. Discrimination for the base model with addition of surgical margin status was high (c-index = 0.801) and not meaningfully improved by adding surgical margin subclassification in the full cohort. In analyses considering only men with PSMs (N = 55 with BCR), adding surgical margin subclassification to the base model increased discrimination for total length of all PSMs - alone or with maximum Gleason grade at the margin (c-index improvement = 0.717 to 0.752 and 0.753, respectively). DCA demonstrated a modest benefit to clinical utility with the addition of these parameters. CONCLUSIONS: Specific subclassification parameters add predictive accuracy for BCR and may aid clinical utility in decision-making for patients with PSMs. These findings may be useful for patient counselling and future adjuvant therapy trial design.

Adverse histology, homozygous loss of CDKN2A/B, and complex genomic alterations in locally advanced/metastatic renal mucinous tubular and spindle cell carcinoma.

Mucinous tubular and spindle cell carcinoma (MTSCC) is a rare subtype of renal cell carcinoma with characteristic histologic features and chromosomal alterations. Although typically indolent, a small subset of cases has been reported to exhibit aggressive clinical behavior. We retrospectively identified 33 patients with MTSCC, consisting of 10 cases of locally advanced/metastatic MTSCC (pT3 or N1 or M1) and 23 kidney-confined MTSCC (pT1/T2) without disease recurrence or progression. Utilizing a single-nucleotide polymorphism array and a targeted next-generation sequencing platform, we examined genome-wide molecular alterations in 24 cases, including 11 available samples from 8 patients with locally advanced/metastatic MTSCC. Ten patients with locally advanced/metastatic MTSCC were 8 females (80%) and 2 males (20%). At nephrectomy, 7 of these 10 cases (70%) were pT3 or pN1 while the remaining 3 (30%) were pT1/T2. Eight patients (80%) developed metastases and common sites included lymph node (4, 40%), bone (4, 40%), and retroperitoneum (3, 30%). Four patients died of disease (40%) during follow-up. Locally advanced/metastatic MTSCCs shared typical MTSCC genomic profiles with loss of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22, while some exhibited additional complex genomic alterations, most frequently a relative gain of 1q (7/8). Homozygous loss of CDKN2A/B was observed in 3 (38%) locally advanced/metastatic MTSCCs. Tumor necrosis, solid nested/sheet pattern, irregular trabecular/single-file infiltration in a desmoplastic stroma, lymphovascular space invasion, and increased mitotic activity were associated with locally advanced/metastatic MTSCCs (all p < 0.05). Our findings reveal that MTSCCs with aggressive clinical behavior have progressed through clonal evolution; CDKN2A/B deletion and additional complex genomic abnormalities may contribute to this process. Recognizing the morphologic presentation of high-grade MTSCC and evaluating adverse histologic features seen in these tumors can help establish a definitive diagnosis and stratify patients for treatment and prognostication.

New developments in existing WHO entities and evolving molecular concepts: The Genitourinary Pathology Society (GUPS) update on renal neoplasia.

The Genitourinary Pathology Society (GUPS) reviewed recent advances in renal neoplasia, particularly post-2016 World Health Organization (WHO) classification, to provide an update on existing entities, including diagnostic criteria, molecular correlates, and updated nomenclature. Key prognostic features for clear cell renal cell carcinoma (RCC) remain WHO/ISUP grade, AJCC/pTNM stage, coagulative necrosis, and rhabdoid and sarcomatoid differentiation. Accrual of subclonal genetic alterations in clear cell RCC including SETD2, PBRM1, BAP1, loss of chromosome 14q and 9p are associated with variable prognosis, patterns of metastasis, and vulnerability to therapies. Recent National Comprehensive Cancer Network (NCCN) guidelines increasingly adopt immunotherapeutic agents in advanced RCC, including RCC with rhabdoid and sarcomatoid changes. Papillary RCC subtyping is no longer recommended, as WHO/ISUP grade and tumor architecture better predict outcome. New papillary RCC variants/patterns include biphasic, solid, Warthin-like, and papillary renal neoplasm with reverse polarity. For tumors with 'borderline' features between oncocytoma and chromophobe RCC, a term "oncocytic renal neoplasm of low malignant potential, not further classified" is proposed. Clear cell papillary RCC may warrant reclassification as a tumor of low malignant potential. Tubulocystic RCC should only be diagnosed when morphologically pure. MiTF family translocation RCCs exhibit varied morphologic patterns and fusion partners. TFEB-amplified RCC occurs in older patients and is associated with more aggressive behavior. Acquired cystic disease (ACD) RCC-like cysts are likely precursors of ACD-RCC. The diagnosis of renal medullary carcinoma requires a negative SMARCB1 (INI-1) expression and sickle cell trait/disease. Mucinous tubular and spindle cell carcinoma (MTSCC) can be distinguished from papillary RCC with overlapping morphology by losses of chromosomes 1, 4, 6, 8, 9, 13, 14, 15, and 22. MTSCC with adverse histologic features shows frequent CDKN2A/2B (9p) deletions. BRAF mutations unify the metanephric family of tumors. The term "fumarate hydratase deficient RCC" ("FH-deficient RCC") is preferred over "hereditary leiomyomatosis and RCC syndrome-associated RCC". A low threshold for FH, 2SC, and SDHB immunohistochemistry is recommended in difficult to classify RCCs, particularly those with eosinophilic morphology, occurring in younger patients. Current evidence does not support existence of a unique tumor subtype occurring after chemotherapy/radiation in early childhood.

Novel, emerging and provisional renal entities: The Genitourinary Pathology Society (GUPS) update on renal neoplasia.

The Genitourinary Pathology Society (GUPS) undertook a critical review of the recent advances in renal neoplasia, particularly focusing on the newly accumulated evidence post-2016 World Health Organization (WHO) classification. In the era of evolving histo-molecular classification of renal neoplasia, morphology is still key. However, entities (or groups of entities) are increasingly characterized by specific molecular features, often associated either with recognizable, specific morphologies or constellations of morphologies and corresponding immunohistochemical profiles. The correct diagnosis has clinical implications leading to better prognosis, potential clinical management with targeted therapies, may identify hereditary or syndromic associations, which may necessitate appropriate genetic testing. We hope that this undertaking will further facilitate the identification of these entities in practice. We also hope that this update will bring more clarity regarding the evolving classification of renal neoplasia and will further reduce the category of "unclassifiable renal carcinomas/tumors". We propose three categories of novel entities: (1) "Novel entity", validated by multiple independent studies; (2) "Emerging entity", good compelling data available from at least two or more independent studies, but additional validation is needed; and (3) "Provisional entity", limited data available from one or two studies, with more work required to validate them. For some entities initially described using different names, we propose new terminologies, to facilitate their recognition and to avoid further diagnostic dilemmas. Following these criteria, we propose as novel entities: eosinophilic solid and cystic renal cell carcinoma (ESC RCC), renal cell carcinoma with fibromyomatous stroma (RCC FMS) (formerly RCC with leiomyomatous or smooth muscle stroma), and anaplastic lymphoma kinase rearrangement-associated renal cell carcinoma (ALK-RCC). Emerging entities include: eosinophilic vacuolated tumor (EVT) and thyroid-like follicular renal cell carcinoma (TLFRCC). Finally, as provisional entities, we propose low-grade oncocytic tumor (LOT), atrophic kidney-like lesion (AKLL), and biphasic hyalinizing psammomatous renal cell carcinoma (BHP RCC).

[Molecular pathology of urogenital tumors : Recommendations from the 2019 International Society of Urological Pathology (ISUP) Consensus Conference]. / Molekularpathologie bei urologischen Tumoren : Empfehlungen der Konsenskonferenz der Internationalen Gesellschaft für Uropathologie (ISUP) 2019.

Comprehensive understanding of molecular principles in cancer and the diversification of oncological therapy promise individual therapeutic concepts, which have not yet found their way into urogenital cancer therapy. In March 2019 the International Society of Urogenital Pathology (ISUP) therefore held a consensus conference on recommendations for molecular diagnostics of genitourinary tumors, which were published in five separate manuscripts and are summarized in this article.In preparation for the conference, a comprehensive survey of current practices for molecular testing of urogenital tumors was carried out by members of the ISUP. At the conference, the results and the corresponding background information were presented by five working groups and recommendations for action for diagnostics were developed. An agreement between 66% of the conference participants was defined as consensus.

Fumarate hydratase FH c.1431_1433dupAAA (p.Lys477dup) variant is not associated with cancer including renal cell carcinoma.

Fumarate hydratase (FH) mutations underpin the autosomal recessive syndrome. FH deficiency and the autosomal dominant syndrome hereditary leiomyomatosis and renal cell carcinoma (HLRCC). The FH c.1431_1433dupAAA (p.Lys477dup) genomic alteration has been conclusively shown to contribute to FH deficiency when occurring with another FH germline alteration. However, a sufficiently large dataset has been lacking to conclusively determine its clinical significance to cancer predisposition in the heterozygous state. We reviewed a series of 7,571 patients with cancer who received germline results through MSK-IMPACT testing at the Memorial Sloan Kettering Cancer Center. The FH c.1431_1433dupAAA (p.Lys477dup) variant was detected in 24 individuals, none of whom was affected with renal cancer. Eleven of the 372 patients with renal cancer were identified to carried pathogenic FH variants associated with HLRCC. None of these 372 patients with renal cancer carried the FH c.1431_1433dupAAA variant. Our data indicate the FH c.1431_1433dupAAA is not associated with cancer including renal cell carcinoma.

Everolimus plus bevacizumab is an effective first-line treatment for patients with advanced papillary variant renal cell carcinoma: Final results from a phase II trial.

BACKGROUND: We previously reported on a phase 2 study of everolimus plus bevacizumab across various nonclear cell renal cell carcinoma (nccRCC) histologies and observed encouraging activity among patients with papillary RCC (pRCC) and unclassified RCC (uRCC) with a major papillary component. We subsequently expanded the study to enroll additional patients with pRCC variants. METHODS: Everolimus plus bevacizumab was administered at standard doses until disease progression or intolerance to therapy. The primary endpoint was the 6-month progression-free survival (PFS) rate; secondary endpoints included objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and safety. Correlative analyses included next-generation sequencing (NGS) from tumor and germline across >341 genes of interest. RESULTS: In addition to 19 patients with pRCC variants in the original cohort, 20 patients with similar features were enrolled on the expansion cohort (uRCC with papillary features [n = 24], pRCC [n = 14], and translocation-associated RCC with papillary features [n = 1]). Among 37 evaluable patients, the 6-month PFS rate was 78%, the median PFS was 13.7 months (95% CI, 10.8-16.4 months), and the ORR was 35%. With a median follow-up of 17.6 months, the median OS was 33.9 months (95% CI, 23.3-71.9). Tolerance was consistent with prior reports for everolimus plus bevacizumab. NGS results (n = 33) identified responses in patients with a wide spectrum of genomic alterations, including ARID1A, FH, and MET mutations. CONCLUSION: The expansion cohort results confirm robust activity of everolimus plus bevacizumab in metastatic pRCC variants, supporting this regimen as a standard option for this patient population.

Genomic landscape of inverted urothelial papilloma and urothelial papilloma of the bladder.

Inverted urothelial papilloma (IUP) and urothelial papilloma (UP) are rare urothelial neoplasms that typically follow a benign clinical course. Oncogenic mutations in FGFR3, HRAS, and the TERT promoter have been reported in these entities but no comprehensive molecular analysis has been performed. We sought to characterize the genomic landscape of IUP and UP using whole-exome and targeted next-generation sequencing. In IUP, 10 of 11 tumors harbored oncogenic hotspot mutations in HRAS and the remaining tumor had an oncogenic KRAS mutation. None of the IUP tumors harbored TERT promoter or FGFR3 mutations. In UP, 8 of 11 tumors had oncogenic KRAS mutations and two had oncogenic HRAS mutations. One UP tumor had oncogenic mutations in FGFR3, PIK3CA, and the TERT promoter, and arose in a patient with recurrent non-invasive papillary urothelial carcinomas. In contrast to urothelial carcinoma, the APOBEC mutational signature was not present in any IUP and UP tumors, and oncogenic alterations in chromatin remodeling genes were uncommon in both IUP and UP. The current study suggests that IUP and UP are driven primarily by RAS pathway activation and lack the more common genomic features of urothelial cancers. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Distinctive mechanisms underlie the loss of SMARCB1 protein expression in renal medullary carcinoma: morphologic and molecular analysis of 20 cases.

Renal medullary carcinoma is a rare but highly aggressive type of renal cancer occurring in patients with sickle cell trait or rarely with other hemoglobinopathies. Loss of SMARCB1 protein expression, a core subunit of the switch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex, has emerged as a key diagnostic feature of these tumors. However, the molecular mechanism underlying this loss remains unclear. We retrospectively identified 20 patients diagnosed with renal medullary carcinoma at two institutions from 1996 to 2017. All patients were confirmed to have sickle cell trait, and all tumors exhibited a loss of SMARCB1 protein expression by immunohistochemistry. The status of SMARCB1 locus was examined by fluorescence in situ hybridization (FISH) using 3-color probes, and somatic alterations were detected by targeted next-generation sequencing platforms. FISH analysis of all 20 cases revealed 11 (55%) with concurrent hemizygous loss and translocation of SMARCB1, 6 (30%) with homozygous loss of SMARCB1, and 3 (15%) without structural or copy number alterations of SMARCB1 despite protein loss. Targeted sequencing revealed a pathogenic somatic mutation of SMARCB1 in one of these 3 cases that were negative by FISH. Tumors in the 3 subsets with different FISH findings largely exhibited similar clinicopathologic features, however, homozygous SMARCB1 deletion was found to show a significant association with the solid growth pattern, whereas tumors dominated by reticular/cribriform growth were enriched for SMARCB1 translocation. Taken together, we demonstrate that different molecular mechanisms underlie the loss of SMARCB1 expression in renal medullary carcinoma. Biallelic inactivation of SMARCB1 occurs in a large majority of cases either via concurrent hemizygous loss and translocation disrupting SMARCB1 or by homozygous loss.

Tubulocystic renal cell carcinoma: a distinct clinicopathologic entity with a characteristic genomic profile.

Tubulocystic renal cell carcinoma, a unique tumor, was recently included as a new entity in the World Health Organization classification of renal tumors. It has variably been reported to be related to other renal cell carcinomas, including papillary renal cell carcinoma, fumarate hydratase-deficient carcinoma, and others, likely because many such carcinomas may show variable amounts of tubulocystic architecture. The published data characterizing the molecular features of these tumors are inconsistent. We studied nine "pure" tubulocystic renal cell carcinomas, as defined by International Society of Urologic Pathologists (ISUP) and World Health Organization (WHO), by targeted next-generation sequencing, and fluorescence in situ hybridization for X and Y chromosomes, to investigate if these show any unique characteristics or any overlap with known mutational/molecular profiles or copy number alterations in other subtypes of renal cell carcinoma. All nine tubulocystic carcinomas demonstrated combined losses at chromosome 9 and gains at chromosome 17, as well as, loss of chromosome Y (in 5/5). None of the tumors showed mutational profiles characteristic of other renal neoplasms, including those seen in fumarate hydratase-deficient renal cell carcinoma. Recurrent mutations in chromatin-modifying genes, KMT2C and KDM5C, were detected in two of nine tumors. Thus, tubulocystic renal cell carcinoma, if defined strictly, at the clinical and pathologic level, demonstrates genomic features distinct from other subtypes of renal cell carcinoma. These findings support the contention that tubulocystic renal cell carcinoma should be diagnosed only using strict morphological criteria and only when presenting in a "pure" form; presence of variable papillary, poorly differentiated, or other architectural patterns most likely do not belong to the category of tubulocystic renal cell carcinoma.

JAK2/PD-L1/PD-L2 (9p24.1) amplifications in renal cell carcinomas with sarcomatoid transformation: implications for clinical management.

Amplifications of JAK2, PD-L1, and PD-L2 at 9p24.1 lead to constitutive expression of PD-L1. This, coupled with JAK2-activation dependent upregulation of PD-L1 and adaptive/induced expression leads to higher tumor PD-L1 expression and immune evasion. Renal tumors were therefore evaluated for 9p24.1 amplifications. A combination of next generation sequencing-based copy number analysis, fluorescence in situ hybridization for JAK2/INSL6 and PD-L1/PD-L2 and immunohistochemistry for phospho-STAT3 (downstream target of JAK2), PD-L1, PD-L2, and PD-1 was performed. In this study we interrogated a "Discovery" cohort of 593 renal tumors, a "Validation" cohort of 398 high-grade renal tumors, The Cancer Genome Atlas (879 cases) and other public datasets (846 cases). 9p24.1 amplifications were significantly enriched in renal tumors with sarcomatoid transformation (5.95%, 15/252) when compared to all histologic subtypes in the combined "Discovery", "Validation" and public datasets (16/2636, 0.6%, p < 0.00001). Specifically, 9p24.1 amplifications amongst sarcomatoid tumors in public datasets, the "Discovery" and "Validation" cohorts were 7.7% (6/92), 15.1% (5/33), and 3.1% (4/127), respectively. Herein, we describe 13 cases and amplification status for these was characterized using next generation sequencing (n = 9) and/or fluorescence in situ hybridization (n = 10). Correlation with PD-L1 immunohistochemistry (n = 10) revealed constitutive expression (mean H-score: 222/300, n = 10). Analysis of outcomes based on PD-L1 expression in tumor cells performed on 282 cases ("Validation" cohort) did not reveal a significant prognostic effect and was likely reflective of advanced disease. A high incidence of constitutive PD-L1 expression in tumor cells in the "Validation" cohort (H-Score ≥250/300) was noted amongst 83 rhabdoid (6%) and 127 sarcomatoid renal tumors (7.1%). This suggests additional mechanisms of constitutive expression other than amplification events. Importantly, two patients with 9p24.1-amplified sarcomatoid renal tumors showed significant response to immunotherapy. In summary, a subset of renal tumors with sarcomatoid transformation exhibits constitutive PD-L1 overexpression and these patients should be evaluated for enhanced response to immunotherapy.

Clinical Usefulness of Prostate and Tumor Volume Related Parameters following Radical Prostatectomy for Localized Prostate Cancer.

PURPOSE: We evaluated whether the prediction of biochemical recurrence after radical prostatectomy is enhanced by any of 6 parameters, including prostate volume, total tumor volume, high grade total tumor volume, the ratio of high grade total tumor volume to total tumor volume, the ratio of total tumor volume to prostate volume and/or the ratio of high grade total tumor volume to prostate volume. MATERIALS AND METHODS: A total of 1,261 patients who underwent radical prostatectomy during a 3-year period had tumor maps constructed with the Gleason pattern denoted as low-3 or high-4 or 5 and volumetric data generated using commercially available software. Univariate Cox regression models were used to assess whether each volume related parameter was associated with biochemical recurrence after radical prostatectomy. A multivariable Cox regression base model (age, prostate specific antigen, Gleason score/grade group, pathological stage and margin status) was compared with 6 additional models (base model plus each volume related parameter) to evaluate enhancement in predictive accuracy. Decision curve analysis was performed to determine the clinical utility of parameters that enhanced predictive accuracy. RESULTS: On univariate analysis each parameter was significantly associated with biochemical recurrence except prostate volume. Predictive accuracy of the multivariable base model was high (c-index = 0.861). Adding volume related parameters marginally enhanced discrimination. Decision curve analysis failed to show added benefit even for high grade total tumor volume/total tumor volume, which was the parameter with the highest discriminative improvement. CONCLUSIONS: Tumor volume related parameters are significantly associated with radical prostatectomy but do not add important discrimination to standard clinicopathological variables for radical prostatectomy prediction or provide benefit across a range of clinically relevant decision thresholds. Volume related measurement is not warranted in routine pathological evaluation and reporting.

Clinical Usefulness of Total Length of Gleason Pattern 4 on Biopsy in Men with Grade Group 2 Prostate Cancer.

PURPOSE: To our knowledge the ideal methodology of quantifying secondary Gleason pattern 4 in men with Grade Group 2/Gleason score 3 + 4 = 7 on biopsy remains unknown. We compared various methods of Gleason pattern 4 quantification and evaluated associations with adverse pathology findings at radical prostatectomy. MATERIALS AND METHODS: A total of 457 men with Grade Group 2 prostate cancer on biopsy subsequently underwent radical prostatectomy at our institution. Only patients with 12 or more reviewed cores were included in analysis. We evaluated 3 methods of quantifying Gleason pattern 4, including the maximum percent of Gleason pattern 4 in any single core, the overall percent of Gleason pattern 4 (Gleason pattern 4 mm/total cancer mm) and the total length of Gleason pattern 4 in mm across all cores. Adverse pathology features at radical prostatectomy were defined as Gleason score 4 + 3 = 7 or greater (Grade Group 3 or greater), and any extraprostatic extension, seminal vesical invasion and/or lymph node metastasis. A training/test set approach and multivariable logistic regression were used to determine whether Gleason pattern 4 quantification methods could aid in predicting adverse pathology. RESULTS: On multivariable analysis all Gleason pattern 4 quantification methods were significantly associated with an increased risk of adverse pathology (p <0.0001) and an increased AUC beyond the base model. The largest AUC increase was 0.044 for the total length of Gleason pattern 4 (AUC 0.728, 95% CI 0.663-0.793). Decision curve analysis demonstrated an increased clinical net benefit with the addition of Gleason pattern 4 quantification to the base model. The total length of Gleason pattern 4 clearly provided the largest net benefit. CONCLUSIONS: Our findings support the inclusion of Gleason pattern 4 quantification in the pathology reports and risk prediction models of patients with Grade Group 2/Gleason score 3 + 4 = 7 prostate cancer. The total length of Gleason pattern 4 across all cores provided the strongest benefit to predict adverse pathology features.

Leiomyoma with bizarre nuclei: a morphological, immunohistochemical and molecular analysis of 31 cases.

Leiomyomas associated with hereditary leiomyomatosis and renal cell carcinoma syndrome and leiomyomas with bizarre nuclei often show overlapping morphological features, in particular cells with prominent eosinophilic nucleoli, perinucleolar halos, and eosinophilic cytoplasmic inclusions. Although hereditary leiomyomatosis and renal cell carcinoma syndrome is defined by fumarate hydratase (FH) germline mutations, resulting in S-(2-succino)-cysteine (2SC) formation, it is unknown whether leiomyomas with bizarre nuclei show similar alterations. In this study, we evaluated the morphology and FH/2SC immunoprofile of 31 leiomyomas with bizarre nuclei. DNA from tumor and normal tissues from 24 cases was subjected to massively parallel sequencing targeting 410 key cancer genes. Somatic genetic alterations were detected using state-of-the-art bioinformatics algorithms. No patient reported a personal history of renal neoplasia or cutaneous leiomyomas, but one had a family history of renal cell carcinoma while another had a family history of uterine leiomyomas. Aberrant FH/2SC expression was noted in 17 tumors (16 FH-negative/2SC-positive, 1 FH-positive/2SC-positive). On univariate analysis, staghorn vessels, eosinophilic cytoplasmic inclusions, diffuse distribution of prominent eosinophilic nucleoli with perinucleolar halos, and an 'alveolar pattern of edema' were associated with an abnormal immunoprofile, but only staghorn vessels remained significant on multivariate analysis. Massively parallel sequencing analysis (n=24) revealed that 13/14 tumors with aberrant FH/2SC immunoprofile harbored somatic FH somatic genetic alterations, including homozygous deletions (n=9), missense mutations coupled with loss of heterozygosity (n=3), and a splice site mutation (n=1), whereas no somatic FH mutations/deletions were found in tumors with normal immunoprofile (n=10; P<0.0001). Leiomyomas with bizarre nuclei with normal FH/2SC staining pattern more frequently harbored TP53 and/or RB1 alterations than those with aberrant FH/2SC immunoprofile (60 vs 14%; P=0.032). These data demonstrate that leiomyomas with bizarre nuclei are morphologically and genetically heterogeneous and that hereditary leiomyomatosis and renal cell carcinoma syndrome-related morphological features, abnormal FH/2SC staining, and somatic FH mutations/deletions can be seen in a subset of sporadic tumors.