Succinate dehydrogenase (SDH)-deficient renal cell carcinoma (RCC) is a rare subtype of renal neoplasm predominantly affecting younger individuals. It is characterized by germline mutations in SDHx genes, particularly type B. Histologically, SDH-deficient RCC features eosinophilic cytoplasmic cells forming solid nests or microcysts, sometimes entrapping normal tubules. We present three SDH-deficient RCC cases with overlapping morphological features with fumarate hydratase-deficient RCC and TFEB-rearranged RCC, an appearance that has not been previously described. All tumors lacked SDHB expression and harbored pathogenic SDHB mutations, with the germline nature confirmed in two cases. Metastasis developed in two patients. Our case set highlights the diagnostic challenges of molecularly defined renal tumors and expands the morphological spectrum of SDH-deficient RCC with unusual histological features. Clinically, these tumors appear to be aggressive.

• Keywords
• RCC, Renal cell carcinoma, SDHB, Succinate dehydrogenase,
• MeSH
• Cell Dedifferentiation MeSH
• Adult MeSH
• Fumarate Hydratase deficiency   genetics   MeSH
• Carcinoma, Renal Cell * genetics   pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Biomarkers, Tumor genetics   analysis   MeSH
• Kidney Neoplasms * pathology   genetics   MeSH
• Aged MeSH
• Succinate Dehydrogenase * deficiency   genetics   MeSH
• Basic Helix-Loop-Helix Leucine Zipper Transcription Factors genetics   MeSH
• Germ-Line Mutation MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Publication type
• Journal Article MeSH
• Case Reports MeSH
• Names of Substances
• Fumarate Hydratase MeSH
• Biomarkers, Tumor MeSH
• SDHB protein, human MeSH Browser
• Succinate Dehydrogenase * MeSH
• TFEB protein, human MeSH Browser
• Basic Helix-Loop-Helix Leucine Zipper Transcription Factors MeSH

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.

• MeSH
• Humans MeSH
• Kidney Neoplasms * MeSH
• World Health Organization MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Practice Guideline MeSH

ALK rearranged renal cell carcinoma (ALK-RCC) has recently been included in 2016 WHO classification as a provisional entity. In this study, we describe 12 ALK-RCCs from 8 institutions, with detailed clinical, pathological, immunohistochemical (IHC), fluorescence in situ hybridization (FISH), and next generation sequencing (NGS) analyses. Patients' age ranged from 25 to 68 years (mean, 46.3 years). Seven patients were females and five were males (M:F = 1:1.4). Tumor size ranged from 17 to 70 mm (mean 31.5, median 25 mm). The pTNM stage included: pT1a (n = 7), pT1b (n = 1), and pT3a (n = 4). Follow-up was available for 9/12 patients (range: 2 to 153 months; mean 37.6 months); 8 patients were alive without disease and one was alive with distant metastases. The tumors demonstrated heterogeneous, 'difficult to classify' morphology in 10/12 cases, typically showing diverse architectural and cellular morphologies, including papillary, tubular, tubulocystic, solid, sarcomatoid (spindle cell), rhabdoid, signet-ring cell, and intracytoplasmic vacuoles, often set in a mucinous background. Of the remaining two tumors, one showed morphology resembling mucinous tubular and spindle cell renal cell carcinoma (MTSC RCC-like) and one was indistinguishable from metanephric adenoma. One additional case also showed a focal metanephric adenoma-like area, in an otherwise heterogeneous tumor. By IHC, all tumors were diffusely positive for ALK and PAX8. In both cases with metanephric adenoma-like features, WT1 and ALK were coexpressed. ALK rearrangement was identified in 9/11 tumors by FISH. ALK fusion partners were identified by NGS in all 12 cases, including the previously reported: STRN (n = 3), TPM3 (n = 3), EML4 (n = 2), and PLEKHA7 (n = 1), and also three novel fusion partners: CLIP1 (n = 1), KIF5B (n = 1), and KIAA1217 (n = 1). ALK-RCC represents a genetically distinct entity showing a heterogeneous histomorphology, expanded herein to include unreported metanephric adenoma-like and MTSC RCC-like variants. We advocate a routine ALK IHC screening for "unclassifiable RCCs" with heterogeneous features.

• MeSH
• Anaplastic Lymphoma Kinase genetics   MeSH
• Adult MeSH
• Gene Fusion * MeSH
• Gene Rearrangement * MeSH
• In Situ Hybridization, Fluorescence MeSH
• Immunohistochemistry MeSH
• Carcinoma, Renal Cell enzymology   genetics   secondary   MeSH
• Kinesins genetics   MeSH
• Middle Aged MeSH
• Humans MeSH
• Biomarkers, Tumor genetics   MeSH
• Neoplasm Proteins genetics   MeSH
• Kidney Neoplasms enzymology   genetics   pathology   MeSH
• Microtubule-Associated Proteins genetics   MeSH
• Proteins genetics   MeSH
• Retrospective Studies MeSH
• Aged MeSH
• High-Throughput Nucleotide Sequencing MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Multicenter Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Asia MeSH
• Europe MeSH
• North America MeSH
• Names of Substances
• ALK protein, human MeSH Browser
• Anaplastic Lymphoma Kinase MeSH
• cytoplasmic linker protein 170 MeSH Browser
• KIAA1217 protein, human MeSH Browser
• KIF5B protein, human MeSH Browser
• Kinesins MeSH
• Biomarkers, Tumor MeSH
• Neoplasm Proteins MeSH
• Microtubule-Associated Proteins MeSH
• Proteins MeSH

Renal cell carcinoma (RCC) subtypes are increasingly being discerned via their molecular underpinnings. Frequently this can be correlated to histologic and immunohistochemical surrogates, such that only simple targeted molecular assays, or none at all, are needed for diagnostic confirmation. In clear cell RCC, VHL mutation and 3p loss are well known; however, other genes with emerging important roles include SETD2, BAP1, and PBRM1, among others. Papillary RCC type 2 is now known to include likely several different molecular entities, such as fumarate hydratase (FH) deficient RCC. In MIT family translocation RCC, an increasing number of gene fusions are now described. Some TFE3 fusion partners, such as NONO, GRIPAP1, RBMX, and RBM10 may show a deceptive fluorescence in situ hybridization result due to the proximity of the genes on the same chromosome. FH and succinate dehydrogenase deficient RCC have implications for patient counseling due to heritable syndromes and the aggressiveness of FH-deficient RCC. Immunohistochemistry is increasingly available and helpful for recognizing both. Emerging tumor types with strong evidence for distinct diagnostic entities include eosinophilic solid and cystic RCC and TFEB/VEGFA/6p21 amplified RCC. Other emerging entities that are less clearly understood include TCEB1 mutated RCC, RCC with ALK rearrangement, renal neoplasms with mutations of TSC2 or MTOR, and RCC with fibromuscular stroma. In metastatic RCC, the role of molecular studies is not entirely defined at present, although there may be an increasing role for genomic analysis related to specific therapy pathways, such as for tyrosine kinase or MTOR inhibitors.

• MeSH
• Neoplastic Syndromes, Hereditary diagnosis   genetics   metabolism   pathology   MeSH
• In Situ Hybridization, Fluorescence MeSH
• Immunohistochemistry MeSH
• Carcinoma, Renal Cell diagnosis   genetics   metabolism   pathology   MeSH
• Pathology, Clinical MeSH
• Humans MeSH
• Neoplasm Metastasis MeSH
• Pathology, Molecular MeSH
• Mutation MeSH
• Biomarkers, Tumor * genetics   metabolism   MeSH
• Kidney Neoplasms diagnosis   genetics   metabolism   pathology   MeSH
• Prognosis MeSH
• Societies, Medical MeSH
• Urology MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Consensus Development Conference MeSH
• Practice Guideline MeSH
• Names of Substances
• Biomarkers, Tumor * MeSH

Renal epithelial cell tumors are composed of a heterogeneous group of tumors with variable morphologic, immunohistochemical, and molecular features. A "histo-molecular" approach is now an integral part of defining renal tumors, aiming to be clinically and therapeutically pertinent. Most renal epithelial tumors including the new and emerging entities have distinct molecular and genetic features which can be detected using various methods. Most renal epithelial tumors can be diagnosed easily based on pure histologic findings with or without immunohistochemical examination. Furthermore, molecular-genetic testing can be utilized to assist in arriving at an accurate diagnosis. In this review, we presented the most current knowledge concerning molecular-genetic aspects of renal epithelial neoplasms, which potentially can be used in daily diagnostic practice.

• Keywords
• kidney, molecular genetic features, practical approach, renal cell carcinoma, review,
• Publication type
• Journal Article MeSH
• Review MeSH

Renal medullary carcinomas (RMCs) and collecting duct carcinomas (CDCs) are rare subsets of lethal high-stage, high-grade distal nephron-related adenocarcinomas with a predilection for the renal medullary region. Recent findings have established an emerging group of fumarate hydratase (FH)-deficient tumors related to hereditary leiomyomatosis and renal cell carcinoma (HLRCC-RCCs) syndrome within this morphologic spectrum. Recently developed, reliable ancillary testing has enabled consistent separation between these tumor types. Here, we present the clinicopathologic features and differences in the morphologic patterns between RMC, CDC, and FH-deficient RCC in consequence of these recent developments. This study included a total of 100 cases classified using contemporary criteria and ancillary tests. Thirty-three RMCs (SMARCB1/INI1-deficient, hemoglobinopathy), 38 CDCs (SMARCB1/INI1-retained), and 29 RCCs defined by the FH-deficient phenotype (FH/2SC or FH/2SC with FH mutation, regardless of HLRCC syndromic stigmata/history) were selected. The spectrum of morphologic patterns was critically evaluated, and the differences between the morphologic patterns present in the 3 groups were analyzed statistically. Twenty-five percent of cases initially diagnosed as CDC were reclassified as FH-deficient RCC on the basis of our contemporary diagnostic approach. Among the different overlapping morphologic patterns, sieve-like/cribriform and reticular/yolk sac tumor-like patterns favored RMCs, whereas intracystic papillary and tubulocystic patterns favored FH-deficient RCC. The tubulopapillary pattern favored both CDCs and FH-deficient RCCs, and the multinodular infiltrating papillary pattern favored CDCs. Infiltrating glandular and solid sheets/cords/nested patterns were not statistically different among the 3 groups. Viral inclusion-like macronucleoli, considered as a hallmark of HLRCC-RCCs, were observed significantly more frequently in FH-deficient RCCs. Despite the overlapping morphology found among these clinically aggressive infiltrating high-grade adenocarcinomas of the kidney, reproducible differences in morphology emerged between these categories after rigorous characterization. Finally, we recommend that definitive diagnosis of CDC should only be made if RMC and FH-deficient RCC are excluded.

• MeSH
• Biopsy MeSH
• Diagnosis, Differential MeSH
• Child MeSH
• Adult MeSH
• Kidney Medulla enzymology   pathology   MeSH
• Phenotype MeSH
• Fumarate Hydratase deficiency   genetics   MeSH
• Genetic Predisposition to Disease MeSH
• Immunohistochemistry MeSH
• Carcinoma, Renal Cell classification   enzymology   genetics   pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Mutation MeSH
• DNA Mutational Analysis MeSH
• Biomarkers, Tumor deficiency   genetics   MeSH
• Kidney Neoplasms classification   enzymology   genetics   pathology   MeSH
• Predictive Value of Tests MeSH
• Retrospective Studies MeSH
• Kidney Tubules, Collecting enzymology   pathology   MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Neoplasm Grading MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Multicenter Study MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Geographicals
• Australia MeSH
• Brazil MeSH
• Europe MeSH
• Canada MeSH
• United States MeSH
• Names of Substances
• Fumarate Hydratase MeSH
• Biomarkers, Tumor MeSH

An emerging group of high-grade renal cell carcinomas (RCCs), particularly carcinomas arising in the hereditary leiomyomatosis renal cell carcinoma syndrome (HLRCC), show fumarate hydratase (FH) gene mutation and loss of function. On the basis of similar cytomorphology and clinicopathologic features between these tumors and cases described as tubulocystic carcinomas with poorly differentiated foci (TC-PD) of infiltrative adenocarcinoma, we hypothesized a relationship between these entities. First, 29 RCCs with morphology of TC-PD were identified retrospectively and assessed for FH expression and aberrant succination (2SC) by immunohistochemistry (IHC), with targeted next-generation sequencing of 409 genes-including FH-performed on a subset. The 29 TC-PD RCCs included 21 males and 8 females, aged 16 to 86 years (median, 46), with tumors measuring 3 to 21 cm (median, 9) arising in the right (n=16) and left (n=13) kidneys. Family history or stigmata of HLRCC were identifiable only retrospectively in 3 (12%). These tumors were aggressive, with 79% showing perinephric extension, nodal involvement in 41%, and metastasis in 86%. Of these, 16 (55%) demonstrated loss of FH by IHC (14/14 with positive 2SC). In contrast, 5 (17%) showed a wild-type immunoprofile of FH+/2SC-. An intriguing group of 8 (28%) showed variable FH± positivity, but with strong/diffuse 2SC+. Next-generation sequencing revealed 8 cases with FH mutations, including 5 FH-/2SC+ and 3 FH±/2SC+ cases, but none in FH+/2SC- cases. Secondly, we retrospectively reviewed the morphology of 2 well-characterized cohorts of RCCs with FH-deficiency determined by IHC or sequencing (n=23 and n=9), unselected for TC-PD pattern, identifying the TC-PD morphology in 10 (31%). We conclude that RCCs with TC-PD morphology are enriched for FH deficiency, and we recommend additional workup, including referral to genetic counseling, for prospective cases. In addition, based on these and other observations, we propose the term "FH-deficient RCC" as a provisional term for tumors with a combination of suggestive morphology and immunophenotype but where genetic confirmation is unavailable upon diagnosis. This term will serve as a provisional nomenclature that will enable triage of individual cases for genetic counseling and testing, while designating these cases for prospective studies of their relationship to HLRCC.

• MeSH
• Neoplastic Syndromes, Hereditary pathology   MeSH
• Adult MeSH
• Fumarate Hydratase deficiency   genetics   MeSH
• Immunohistochemistry MeSH
• Carcinoma, Renal Cell enzymology   genetics   pathology   MeSH
• Leiomyomatosis pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Multiplex Polymerase Chain Reaction MeSH
• Uterine Neoplasms pathology   MeSH
• Skin Neoplasms pathology   MeSH
• Kidney Neoplasms enzymology   genetics   pathology   MeSH
• Retrospective Studies MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• High-Throughput Nucleotide Sequencing MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Fumarate Hydratase MeSH