Evaluation of an institutional series of low-grade oncocytic tumor (LOT) of the kidney and review of the mutational landscape of LOT.

The 2022 WHO classification of urinary and male genital tumors introduced several novel kidney entities exhibiting eosinophilic/oncocytic features with specific mutational backgrounds. Thus, molecular techniques, such as next-generation sequencing (NGS), became more commonly used for their evaluation. We studied 12 low-grade oncocytic tumors (LOT) of the kidney (from 11 patients), identified in a cohort of 210 eosinophilic/oncocytic renal tumors, diagnosed in our institution between October 2019 and May 2023, which represented 5.7% (12/210) of all eosinophilic/oncocytic renal tumors during this period. We reviewed their clinicopathologic, histologic, and immunohistochemical features, as well as their mutational profiles. We also reviewed the literature on NGS-derived data of LOT, by selecting papers in which LOT diagnosis was rendered according to the criteria proposed initially. Median age was 65 years (mean: 63.5; range 43-79) and median tumor size was 2.0 cm (mean: 2.2; range: 0.9-3.1). All tumors were positive for PAX8, CK7, and GATA3, and negative or focally positive for CD117/KIT. We found the following gene mutations: MTOR ((6/11), 54.5%)), TSC1 ((2/11), 18.2%)), and 1 had both NOTCH1 and NOTCH4 ((1/11), 9.1%)). Wild-type status was found in 2/11 (18.2%) patients and one tumor was not analyzable. A review of 8 previous studies that included 79 LOTs revealed frequent mutations in the genes that regulate the mammalian target of rapamycin (mTOR) pathway: MTOR (32/79 (40.5%)), TSC1 (21/79 (26.6%)), and TSC2 (9/79 (11.4%)). Other mutated genes included PIK3CA, NF2, and PTEN, not typically known to affect the mTOR pathway, but potentially acting as upstream and downstream effectors. Our study shows that LOT is increasingly diagnosed in routine practice when applying the appropriate diagnostic criteria. We also confirm that the mTOR pathway is strongly implicated in the pathogenesis of this tumor mainly through MTOR, TCS1, and TSC2 mutations, but other genes could also be involved in the pathway activation, especially in LOTs without "canonical" mutations.

FoxA2 is a reliable marker for the diagnosis of yolk sac tumour postpubertal-type.

AIMS: Yolk sac tumour postpubertal-type (YSTpt) shows a wide range of histological patterns and is challenging to diagnose. Recently, forkhead box transcription factor A2 (FoxA2) emerged as a driver of YSTpt formation and a promising marker for diagnosing YSTpt. However, FoxA2 has not been tested in the different patterns of YSTpt. This study aimed to assess the staining pattern of FoxA2 in te different patterns of YSTpt and other germ cell tumours of the testis (GCTT), comparing it with glypican-3 (GPC3) and α-fetoprotein (AFP). METHODS AND RESULTS: FOXA2, GPC3 and AFP immunohistochemistry was performed on 24 YSTpt (24 microcystic/reticular, 10 myxoid, two macrocystic, five glandular/alveolar, two endodermal sinus/perivascular, four solid, two polyembryoma/embryoid body and two polyvesicular vitelline) and 81 other GCTT. The percentage of positive cells (0, 1+, 2+, 3+) and the intensity (0, 1, 2, 3) were evaluated regardless of and within each YSTpt pattern. FoxA2 was positive in all YSTpt (24 of 24) and all but one (23 of 24) exhibited 2+/3+ stain, with higher intensity [median value (mv): 2.6] than AFP (1.8) and GPC3 (2.5). Both FoxA2 and GPC3 were positive in all microcystic/reticular (24 of 24), myxoid (10 of 10), macrocystic (two of two), endodermal sinus/perivascular (four of four) and polyembryoma/embryoid body (two of two) patterns. Nevertheless, only FoxA2 was positive in all glandular/alveolar (five of five), solid (four of four) and polyvesicular vitelline (two of two) patterns. The intensity of FoxA2 was higher than AFP and GPC3 in almost all YST patterns. In the other GCTT, FoxA2 was positive only in teratoma postpubertal-type (Tpt) [13 of 20 (65%)], with staining almost exclusively confined to the mature gastrointestinal/respiratory tract epithelium. CONCLUSIONS: FoxA2 is a highly sensitive and specific biomarker that supports the diagnosis of YSTpt. FoxA2 is superior to GPC3 and AFP, especially in rare and difficult-to-diagnose histological patterns of YSTpt, but mature glands of Tpt could represent a potential diagnostic pitfall.

TAMs PD-L1(+) in the reprogramming of germ cell tumors of the testis.

BACKGROUND: In recent years, several studies focused on the process of reprogramming of seminoma (S) cells, which regulates the transition from pure S (P-S) to S component (S-C) of mixed germ cell tumors of the testis (GCTT) and finally to embryonal carcinoma (EC) and other nonseminomatous GCTT (NS-GCTT). The accepted pathogenetic model is driven and regulated by cells (macrophages, B- and T-lymphocytes) and molecules of the tumor microenvironment (TME). Herein, we tested a series of GCTT with double staining (DS) for CD68-PD-L1 to evaluate tumor-associated macrophages (TAMs) expressing programmed death-ligand 1 (PD-L1) [TAMs PD-L1(+)] and clarify if these cells may be involved in establishing the fate of GCTT. METHODS: We collected 45 GCTT (comprising a total of 62 different components of GCTT). TAMs PD-L1(+) were evaluated with three different scoring systems [TAMs PD-L1(+)/mm2, TAMs PD-L1(+)/mm2H-score, TAMs PD-L1(+) %], and compared using pertinent statistic tests (Student's t-test and Mann-Whitney U test). RESULTS: We found that TAMs PD-L1(+) values were higher in S rather than EC (p = 0.001, p = 0.015, p = 0.022) and NS-GCTT (p < 0.001). P-S showed statistically significant differences in TAMs PD-L1(+) values compared to S-C (p < 0.001, p = 0.006, p = 0.015), but there were no differences between S-C and EC (p = 0.107, p = 0.408, p = 0.800). Finally, we found statistically significant differences also in TAMs PD-L1(+) values between EC and other NS-GCTT (p < 0.001). CONCLUSIONS: TAMs PD-L1(+) levels gradually decrease during the reprogramming of S cells {P-S [(high values of TAMs PD-L1(+)] → S-C and EC [(intermediate values of TAMs PD-L1(+)] → other NS-GCTT [(low values of TAMs PD-L1(+)], supporting a complex pathogenetic model where the interactions between tumor cells and TME components [and specifically TAMs PD-L1(+)] play a key role in determining the fate of GCTT.

H&E and OCT4/CD34 for the assessment of lympho-vascular invasion in seminoma and embryonal carcinoma.

BACKGROUND: Lymphovascular invasion (LVI) is a relevant prognostic factor in germ cell tumors of the testis (GCTT), and it is included in the pT stage. However, its detection on hematoxylin and eosin (H&E) slides is very challenging, and previous studies reported fair to moderate inter-observer agreement among dedicated uropathologists. In the present study, we tested H&E and a recently developed in-house double staining for OCT4/CD34 to detect LVI in GCTT. METHODS: Nine authors [5 non-uropathologists and 4 uropathologists] independently evaluated 34 consecutive and retrospectively enrolled cases of GCTT. We assessed the inter-observer agreement (Fleiss's Kappa) with both H&E and OCT4/CD34. Besides, we compared the consensus diagnosis on both H&E and OCT4/CD34-stained sections with the original diagnosis to evaluate the pT re-staging (McNemar test) and identify the sources of disagreement. RESULTS: The inter-observer agreement among uropathologists plus non-uropathologists was fair with both H&E (KF=0.398; p < 0.001) and OCT4/CD34 (KF=0.312; p < 0.001). OCT4/CD34 (KF=0.290; p < 0.001) slightly reduces the inter-observer agreement compared to H&E (KF=0.321; p < 0.001) for non-uropathologists; in contrast, OCT4/CD34 (KF=0.293; p < 0.001) significantly reduces the inter-observer agreement compared to H&E (KF=0.529; p < 0.001) for uropathologists, changing it from moderate to fair. Consensus diagnosis with H&E modified the LVI status of the original diagnosis in 8/34 (23.5 %) cases (p: 0.070), with pT re-staging in 2/34 (5.9 %) cases (p: 0.500). Consensus diagnosis with OCT4/CD34 modified the LVI status of the original diagnosis in 8/34 (23.5 %) cases (p: 0.289), with pT re-staging in 3/34 (8.8 %) cases (p: 0.250). The consensus diagnosis with OCT4/CD34 modified the consensus diagnosis with H&E in 8/34 (23.5 %) cases (p: 0.727), and these findings resulted in pT-restaging in 3/34 (8.8 %) cases (p: 0.500). The sources of disagreement among uropathologists were: H&E [artefactual clefts misinterpreted as LVI in 4/6 (66.7 %) cases and true foci of LVI misinterpreted as clusters of histiocytes within the vessels in 2/6 (33.3 %) cases], OCT4/CD34 [artefactual clefts misinterpreted as LVI in 2/8 (25 %) cases, true LVI misinterpreted as artefactual clefts in 2/8 (25 %) cases or floaters in 4/8 (50 %) cases]. CONCLUSIONS: OCT4/CD34 does not improve the inter-observer agreement for the assessment of LVI in OCT4(+) GCTT. Consensus diagnosis with H&E modifies the LVI status in a significant number of cases, resulting in changes of the pT stage in a relatively small subgroup. Consensus diagnosis with OCT4/CD34 provides little additional benefit since it cannot exclude mimickers of LVI such as floaters and artefactual clefts. These results argue against the adoption of this diagnostic tool for the routine assessment of OCT4(+) GCTT.

Yolk sac tumor of postpubertal-type does not exhibit immunohistochemical loss of SMARCB1/INI1 and SMARCA4/BRG1 but choriocarcinoma?

The recently described SWI/SNF complex-deficient sinonasal carcinoma (SMARCB1 & SMARCA4) may exhibit a yolk sac-like morphology. Tumors with similar features (yolk sac-like histology combined with the immunohistochemical loss of SMARCB1/INI1 and/or SMARCA4/BRG1) have also been described in other sites, such as the female genital tract. In this study, we immunohistochemically assessed SMARCB1/INI1 and SMARCA4/BRG1 expression to evaluate if these proteins could be involved in the pathogenesis of testicular yolk sac tumors of postpubertal type (YSTpt). Specifically, we analyzed a retrospective case series comprising pure YSTpt and mixed germ cell tumors of the testis (GCTT) with YSTpt components. In the present study, no testicular YSTpt showed loss of SMARCB1/INI1 (0/24, 0%) or SMARCA4/BRG1 (0/24, 0%). However, testicular choriocarcinoma (CHC) and isolated syncytiotrophoblast cells (iSTCs) demonstrated abnormal staining patterns for SMARCA4/BRG1 [CHC: 4/4 (100%); iSTCs: 12/12 (100%), respectively], including focal or diffuse loss of expression in a subset of cases. The results of our study suggest that functional loss of SMARCA4/BRG1 represents a recurrent event that may be relevant for the pathogenesis of a subset of testicular CHC.

SOX2 and PRAME in the "reprogramming" of seminoma cells.

BACKGROUND: In recent years, several studies investigated the complex process called "reprogramming" of seminoma (S) cells. The accepted pathogenetic model is a complex network including SOX2, SOX17, OCT3/4 and PRAME, which modulates the epigenetic transcription of numerous downstream genes and drives a divergent gene expression profile resulting in the transition from pure S (P-S) to S component (S-C) of mixed germ cell tumors of the testis (M-GCTT), and finally to embryonal carcinoma (EC). Herein, we tested a large cohort of GCTT with SOX2 and PRAME to evaluate their expression in the evolutionary steps of GCTT and verify if the modulation in the expression of these two molecules could be relevant for the fate of GCTT. METHODS: We tested 43, 19 and 17 consecutive and retrospectively enrolled cases of GCTT, germ cell neoplasia in situ (GCNIS) and uninvolved background testes (UBT), respectively. SOX2 and PRAME expressions have been evaluated with H-score and compared by adopting the appropriate statistic tests (Student's t-test and Mann-Whitney U test). RESULTS: We found that SOX2 was more expressed by nonseminomatous-GCTT (NS-GCTT) (p < 0.001) and EC (p < 0.001) rather than S; by contrast, PRAME showed an opposite expression profile being expressed by S but not by NS-GCTT (p < 0.001) and EC (p < 0.001). S-C showed different expressions of SOX2 and PRAME compared to both P-S (p = 0.002 and <0.001, respectively) and EC (p < 0.001 and 0.042, respectively), with intermediate values between these latter two categories. GCNIS and UBT showed no expression of SOX2 (scattered positive Leydig cells) but high H-score levels of PRAME. CONCLUSIONS: SOX2 and PRAME are differentially expressed and specularly modulated during the "reprogramming" of S cells [P-S (high levels of PRAME, no expression/low levels of SOX2) → S-C (intermediate levels of PRAME, intermediate levels of SOX2) → EC (no expression/low levels of PRAME, high levels of SOX2)], therefore supporting a complex pathogenetic model where the interactions between these two molecules are crucial in determining the fate of GCTT.

Could double stain for p53/CK20 be a useful diagnostic tool for the appropriate classification of flat urothelial lesions?

BACKGROUND: The differential diagnosis between flat urothelial lesions [reactive urothelial atypia (RUA), atypia of unknown significance (AUS), urothelial dysplasia (UD) and carcinoma in situ (CIS)] has relevant prognostic and therapeutic implications. This crucial distinction could be very challenging but it is currently performed on hematoxylin and eosin (H&E) slides, with a great amount of partially discordant and/or not conclusive findings of the potential adjunctive role of immunohistochemistry. Herein, we tested double staining (DS) for p53/CK20 to verify if p53(+) cells, CK20(+) cells and double-positive cells (DPCs) are differentially expressed among these lesions and if p53/CK20 could be a useful tool in this diagnostic setting. METHODS: We tested 50, 9, 36 and 29 consecutive and retrospectively enrolled cases of RUA, AUS, UD and CIS, respectively. p53(+) cells, CK20(+) cells and DPCs were evaluated and compared by adopting the appropriate statistic tests (Mann-Whitney U and Kruskal-Wallis tests). RESULTS: We found that p53(+) cells (p = 0.000), CK20(+) cells (p = 0.000) and DPCs (p = 0.000) showed statistically significant differences among the different flat urothelial lesions. Besides, when dichotomized, both CIS and RUA are easily differentiable from their histological mimickers adopting all these markers; by contrast, AUS and UD did not reach statistically significant differences able to differentiate them from each other [p53(+) cells, p = 0.123; CK20(+) cells, p = 0.567; DPCs, p = 0.409], except if compared to CIS [AUS VS CIS: p53(+) cells, p = 0.013; CK20(+) cells, p = 0.000; DPCs, p = 0.000; UD vs CIS: p53(+) cells, p = 0.000; CK20(+) cells, p = 0.000; DPCs, p = 0.000]. CONCLUSIONS: p53(+) cells, CK20(+) cells and DPCs are differently expressed by flat urothelial lesions and p53/CK20 could be a time- and money-saving tool for the appropriate management of these lesions if applied to a routine scenario.

Immunohistochemical Expression of Preferentially Expressed Antigen in Melanoma (PRAME) in the Uninvolved Background Testis, Germ Cell Neoplasia In Situ, and Germ Cell Tumors of the Testis.

OBJECTIVES: Preferentially expressed antigen in melanoma (PRAME) has a key role in regulating pluripotency of primordial germ cells and in the development of germ cell tumors of the testis (GCTT). However, its immunohistochemical expression in normal testes and its neoplastic counterpart remain largely unknown. METHODS: We retrospectively investigated the expression of PRAME in 26 cases of GCTT, 21 cases of germ cell neoplasia in situ (GCNIS), and 17 cases of uninvolved background testes. RESULTS: We found that PRAME was expressed more strongly by seminomatous rather than nonseminomatous GCTT (P = .000) and by pure seminoma rather than the seminoma component of seminomatous/nonseminomatous GCTT (P = .025). In addition, GCNIS and uninvolved background testes displayed high levels of PRAME expression. CONCLUSIONS: PRAME is an additional marker for the differential diagnosis of GCTT and could play a key role in the transition from seminomatous to nonseminomatous GCTT.

Low level of interobserver concordance in assessing histological subtype and tumor grade in patients with penile cancer may impair patient care.

Differentiation between penile squamous cell carcinoma patients who can benefit from limited organ-sparing surgery and those at significant risk of lymph node metastasis is based on histopathological prognostic factors including histological grade and tumor histological subtype. We examined levels of interobserver and intraobserver agreement in assessment of histological subtype and grade in 207 patients with penile squamous cell carcinoma. The cases were assessed by seven pathologists from three hospitals located in Sweden and Italy. There was poor to moderate concordance in assessing both histological subtype and grade, with Fleiss kappas of 0.25 (range: 0.02-0.48) and 0.23 (range: 0.07-0.55), respectively. When choosing HPV-associated and non-HPV-associated subtypes, interobserver concordance ranged from poor to good, with a Fleiss kappa value of 0.36 (range: 0.02-0.79). A re-review of the slides by two of the pathologists showed very good intraobserver concordance in assessing histological grade and subtype, with Cohen's kappa values of 0.94 and 0.91 for grade and 0.95 and 0.84 for subtype. Low interobserver concordance could lead to undertreatment and overtreatment of many patients with penile cancer, and brings into question the utility of tumor histological subtype and tumor grade in determining patient treatment in pT1 tumors.

A preliminary study investigating the detection of lymphovascular invasion in germ cell tumors of the testis with double staining for OCT4/CD34.

Lymphovascular invasion (LVI) is a relevant prognostic factor in germ cell tumors of the testis (GCTT) and it has been included in the AJCC staging system. Nevertheless, its histological assessment is challenging, with low/moderate interobserver agreement also among expert uropathologists. Few studies focused on the potential role of immunohistochemistry to solve this critical issue; as result, in current guidelines there is no indication for additional staining to detect this histological feature. In the present study, we investigated the detection of LVI invasion in a small cohort of GCTT with double staining for OCT4/CD34. Although our results need to be validated in larger case series with follow-up data, they suggest as OCT4/CD34 could be a useful tool for the histological assessment of these tumors, helping to identify some histological mimickers of LVI and modifying the pT/stage in a significant percentage of patients.

A practical histological approach to the diagnosis of autoimmune hepatitis: experience of an Italian tertiary referral center.

Liver biopsy is crucial for the diagnosis of autoimmune hepatitis (AIH), and new reproducible histological criteria would be highly desirable, especially in acute-on-chronic cases. The aims of the present study were (i) to evaluate the AIH histopathological criteria as a function of the time and modality of AIH onset, and (ii) to validate the count of apoptotic bodies in the portal tracts as a histopathological criterion for AIH diagnosis. Sixty-five patients were retrospectively enrolled: 20 underwent biopsy for the first diagnosis and 45 had a previous histological AIH diagnosis. Biopsies were revised, and all histological variables were collected, including the lymphocytic apoptotic bodies in the portal tracts. Clinical and serological data were revised as well. First-diagnosis patients showed a higher grade of inflammation (p = 0.001), but also worse portal fibrosis (p = 0.001). The apoptotic body count was higher in first-diagnosis patients than in follow-up patients (p = 0.002), and it was strongly correlated to inflammation. Using the apoptotic body count among the simplified AIH score variables, the first-biopsy patients in the "definite" category rose from 42 to 68%. Our results confirm the histopathological criteria proposed by the literature and introduce the count of portal apoptotic bodies for the diagnosis of active AIH, especially in first biopsies without other classic features, as well as in AIH diagnostic score, albeit future studies are required to find a definite cutoff.

Case Report: The Complete Remission of a Mixed Germ Cell Tumor With Somatic Type Malignancy of Sarcoma Type With a GCT-Oriented Therapy: Clinical Findings and Genomic Profiling.

Somatic malignant transformation in a germ cell tumor (GCT) is the development of non-germ malignancies; much of available literature refers to teratoma with malignant transformation (TMT). There are various transformation histologies such as sarcoma, adenocarcinoma, primitive neuroectodermal tumors, and more rarely carcinoid tumors, hemangioendothelioma, lymphoma, or nephroblastoma. The treatments of these entities include surgery and/or chemotherapy. A standard approach in choosing chemotherapy in TMT cases has not yet been established. Many authors suggest using chemotherapeutic agents based on the transformed histology, while others recommend GCT-oriented therapy combined with surgery as the primary treatment, reserving histology-driven chemotherapies for metastatic relapse. We report the clinical findings and the genomic profile of a mixed GCT case with somatic-type malignancy of sarcoma type. We achieved a complete radiological response with GCT-oriented chemotherapy performed as salvage therapy after sarcoma-histology therapy. In addition, molecular profiles with RNA-sequencing and exome sequencing analyses of the primary tumor and the tumor with somatic-type malignancy of sarcoma type were explored.

A narrative review of individualized treatments of genitourinary tumors: is the future brighter with molecular evaluations?

Few molecular prognostic and predictive biomarkers have been identified so far in genitourinary tumors. We started from a literature search to explore the status of the art of molecular pathology tests as diagnostic, prognostic, predictive biomarkers in genitourinary cancers. Next generation sequencing approaches now provide mind-changing information in the fields of kidney cancer diagnosis, predictive oncology of urothelial cancer, understanding the causes of testicular and penile cancer, and the comprehension of the drivers of prostate cancer progression beyond androgen regulation. The classification of kidney cancer will be based soon on molecular changes. The causes of non-HPV related penile cancer are largely unknown. The emerging high incidence of testicular cancer could be explained only on the basis of molecular changes. The response to novel therapeutic agents in prostatic and urothelial cancer will require thorough molecular tumor characterization. The hereditary risk of patients with early onset prostate cancer and their potential treatment with targeted therapy requires germline and somatic genetic assays. The implementation of effective biomarkers for the response to immune check-point inhibitors in genitourinary cancer is based on the assessment of inflammatory expression profiles and the tumor mutational burden. This review deals with the current tests and provides a tentative foresee of the future molecular biomarkers of genitourinary cancer.

Impact of HER2 assessment by CISH in urothelial carcinoma: A retrospective single-center experience.

BACKGROUND: In recent years, HER2 amplification has been evaluated as a potential prognostic biomarker and therapeutic target in urothelial carcinoma (UC). In this retrospective study, we aimed at exploring the prognostic role of HER2 amplification in UC, measured by chromogenic in situ hybridization (CISH). METHODS: We retrospectively evaluated the presence of HER2 amplification by using CISH in 31 UC patients followed at a single institution between 2018 and 2020. The primary objective was to assess the frequency of HER2 amplification and to compare clinical outcomes of HER2-amplified patients with non-amplified UCs. RESULTS: HER2 amplification was identified in 4 out of 31 patients (12.9 %). After a median follow-up of 28.1 months (95 % Confidence Intervals [CI] 11.2-45.1), median overall survival (OS) in the whole population was 10.9 months (95 % CI 3.5-22.1). Despite not reaching statistical significance, median OS was shorter in HER2-amplified patients (6.8 months, 95 % CI 3.9-9.7) compared to HER2-negative UCs (15.4 months, 95 % CI 7.5-23.3) (p = 0.45). CONCLUSIONS: Although limited by the small sample size, the results of our study suggest that HER2 amplifications by CISH could represent a prognostic factor for shorter survival in UC patients.

Renal Tumors with Oncocytic and Papillary Features: A Phenotypic and Genotypic Study.

The occurrence of kidney oncocytic lesions with an admixed papillary component is not unusual in routine pathology practice. These neoplasms with dual morphology are classically recognized as collision tumors with variable malignant potential. Using immunohistochemistry, we investigated fluorescent in situ hybridization and next generation sequencing of the genetic and phenotypic profiles in the two components of 11 kidney tumors with colliding oncocytic and papillary features. The oncocytic component was CD117 positive, CK7 negative, and AMACR negative; the papillary component was CK7 positive, AMACR positive, and CD117 negative in all cases. Fluorescence in situ hybridization (FISH) results were inconsistent. Next generation sequencing (NGS) analysis demonstrated that the mutations identified in the two tumor components were identical and displayed an allelic frequency of approximately 50%, strongly suspicious for genetic polymorphisms. The two oncocytic and papillary tumor counterparts shared the same genetic profile and did not harbor pathogenic mutations. Clinical confirmation of the biological benign features of these tumors is required. The term collision tumor is not suitable for these neoplasms, and we propose the term oncopapillary tumor for this histological entity.

Broad spectrum mutational analysis of chromophobe renal cell carcinoma using next-generation sequencing.

BACKGROUND: Chromophobe renal cell carcinoma (ChRCC) is a rare subtype of non-clear cell renal cell carcinoma. Due to its rarity, its molecular characterization as well as therapeutic targets are still not fully understood. METHODS: We performed a next-generation sequencing analysis using the platform Ion PGM System on 20 retrospectively collected ChRCC cases with the aim of identify molecular biomarkers with potential prognostic value or that could have therapeutic implications. RESULTS: We identified mutation onTP53, SMARCB1, RB1 and JAK3. The most frequently altered gene was TP53 (6/20, 30 % of cases). SMARCB1 mutation was found in 3 (15 %) patients and in all cases the mutational variant was p.T72 K, with known pathogenenic meaning. One (5%) patient presented a pathogenetic mutation of RB1. JAK3 was mutated in 1 (5%) patient and this mutation resulted to have uncertain pathogenetic significance. CONCLUSION: ChRCC is a rare disease still not fully molecularly characterized. Next-generation sequencing analysis could be useful to identify potential mutation with prognostic value or that could be potential therapeutic targets.

Immunohistochemical over-expression of HER2 does not always match with gene amplification in invasive bladder cancer.

BACKGROUND: HER2 is a potential target of therapy in urothelial cancer (UC). Pathological case stratification according to HER2 gene amplification or HER2 protein overexpression was critical for patients' selection in previous unsuccessful clinical trial with HER2 targeting agents. STUDY DESIGN: We evaluated the HER2 overexpression by immunohistochemistry (IHC) together with the amplification of the HER2 gene with chromogenic(CISH) and fluorescent (FISH) in situ hybridization in a cohort of 61 patients covering the whole spectrum of bladder UC variants, using a tissue microarray (TMA) approach. RESULTS: IHC was available in all the 61 cases while ISH in 37 and FISH in 42. At IHC, 2/61 cases (3%) were scored 3+; 2 (3%) scored 2+; 2 (3%) scored 1+; the remaining 55 (91%) scored 0. At CISH analysis 10/37 cases (27%) were amplified, 6 cases with HER2 amplification showed positive HER2 IHC (3+, 2+, 1+). Seven cases with IHC score 0 were amplified at CISH. FISH analysis revealed an amplification in 5/42 cases (12%). The total number of HER2amplified cases was different between chromogenic and fluorescent ISH with 5 cases amplified using FISH compared to 10 with CISH. CONCLUSIONS: In clinical trials with HER2 targeting agents the candidate patients should be investigated not only by IHC but also by ISH, independently of the IHC results. Since also usual type UC can overexpress HER2 we recommend to extend the patients' selection to all the histotypes of bladder cancer other than the micropapillary type.

Similarities and Differences between Clear Cell Tubulo-Papillary and Conventional Clear Cell Renal Cell Carcinoma: A Comparative Phenotypical and Mutational Analysis.

BACKGROUND: Clear cell tubulo-papillary renal cell carcinoma (cctpRCC) is characterized by clear cell morphology, but differs from conventional clear cell carcinoma (ccRCC) for its indolent clinical behavior and genetic background. The differential diagnosis between the two is based on histology and immunohistochemistry (IHC). METHODS: We performed a comparative case-control histological, IHC, and genetic analysis by next generation sequencing (NGS), to point out the differences in 10 cases of cctpRCC, and six controls of ccRCC with low stage and grade. RESULTS: All 16 cases showed the IHC profile with cytokeratin 7, racemase, and carbonic anhydrase IX expected for the histological features of each tumor type. By contrast, the NGS mutation analysis that covered 207 amplicons of 50 oncogenes or tumor suppressor genes provided conflicting results. Among the 10 cctpRCC cases, eight (80%) were wild type for all of the genes in the panel, while two (20%) harbored VHL mutations typical of ccRCC. Three of the six (50%) ccRCC control cases showed expected VHL mutations; two (33%) harbored pathogenic mutations in the p53 or the CKIT genes; and one (16%) was wild type. CONCLUSION: We can assume that histology and ICH are not sufficient for a definitive diagnosis of cctpRCC or ccRCC. Although with a panel covering 50 genes, we found that 80% of cctpRCC were genetically silent; thus, suggesting an indolent biology of these tumors. The differential diagnosis between ccptRCC and ccRCC for the choice of the best therapeutic strategy likely requires the comprehensive evaluation of histology, IHC, and at least VHL mutations.

Challenging liver lesions in noncirrhotic patients: Report of three cases.

We describe three cases of liver lesions, characterized by a discrepancy between presurgical imaging and histological features, in which the final histological diagnosis was quite different from what the surgeons expected. We present (1) a case of primary liver angiomyolipoma associated with focal nodular hyperplasia, (2) a case of perivascular epithelioid cell tumor, and (3) a case of liver splenosis associated with focal nodular hyperplasia. In all cases, a presurgical diagnosis of hepatocellular adenoma was made. Due to nonspecific clinical and radiological features, these rare liver lesions are often presurgically misdiagnosed, especially in young noncirrhotic patients. The association among different lesions represents one additional diagnostic challenge.