Objective:To investigate the expression and diagnostic value of SS18-SSX fusion-specific antibody and SSX C-terminal antibody in synovial sarcoma (SS).Methods:Immunohistochemical (IHC) EnVision method was used to detect the expression of SS18-SSX fusion-specific antibody and SSX C-terminal antibody in 51 genetically confirmed cases of SS and 94 non-SS tumors diagnosed at Nanjing Jinling Hospital from August 2013 to December 2020.Results:IHC staining for SS18-SSX fusion-specific antibody revealed strongly diffuse nuclear staining in 48 of 51 (48/51, 94.1%) SS cases, whereas none of the 94 non-SS tumors showed any staining. IHC staining for SSX C-terminal antibody showed strongly diffuse nuclear staining in all 51 (51/51, 100%) SS cases; six of the 94 (6/94, 6.4%) non-SS tumors showed variable staining, including two cases each of leiomyosarcoma and fibrosarcoma, and one case each of malignant peripheral nerve sheath tumor and embryonal rhabdomyosarcoma. The sensitivity and specificity of SS18-SSX fusion-specific antibody in diagnosing SS were 94.1% and 100% and these of SSX C-terminal antibody were 100% and 93.6%, respectively.Conclusions:SS18-SSX fusion-specific antibody and SSX C-terminal antibody are highly sensitive and specific markers for SS. Immunohistochemistry using these antibodies may replace FISH or molecular genetic testing in most cases.

Objective: To investigate the expression of H3.3 G34W mutant-specific antibody in giant cell tumors of bone (GCTB), and its value in the diagnosis of GCTB. Methods: Immunohistochemical (IHC) EnVision method was used to detect the expression of H3.3 G34W mutant-specific antibody and p63 in 83 GCTBs, 18 aneurysmal bone cysts, 23 chondroblastomas and 28 osteosarcomas diagnosed at Nanjing Jinling Hospital from June 2001 to April 2019. Results: Among the 83 cases of GCTB, 69 cases (69/83, 83.1%) expressed H3.3 G34W. H3.3 G34W expression was found exclusively in the mononuclear cell population with strong and diffuse nuclear staining. H3.3 G34W was expressed in 55 of 57 (96.5%) cases of GCTB in long bones, but only 14 of 26 (53.8%) cases of non-long bone GCTB. All recurrent (9/9)/metastatic GCTB (2/2), post-denosumab GCTB (3/3), primary malignant GCTB (3/3) and secondary malignant GCTB (5/5) also expressed H3.3 G34W. H3.3 G34W was negative in all aneurysmal bone cysts and chondroblastomas. H3.3 G34W was positive in 3 of 28(10.7%) cases of osteosarcomas, and giant cell-rich osteosarcoma(GCRO) was the only histological subtype of osteosarcoma that expressed H3.3 G34W. p63 was expressed in 71.1%(59/83) of GCTB, while the positive rates of p63 in aneurysmal bone cysts,chondroblastomas and osteosarcomas were 3/18, 43.5% (10/23) and 21.4% (6/28) respectively. The sensitivity and specificity of H3.3 G34W mutant-specific antibody in the diagnosis of GCTB were 83.1% and 95.7%. Conclusions H3.3 G34W mutant-specific antibody is a highly sensitive and specific marker for GCTB and helpful for the diagnosis of GCTB and its variants. The limitation of this antibody is that as a mall number of GCTB harbor G34 mutation other than G34W, and thus that cannot be detected. The incidental expression of H3.3 G34W mutant protein in osteosarcoma could be a potential diagnostic dilemma, and the results of H3.3 G34W IHC staining needs careful interpretation.

Objective: To study the clinicopathological features, immunohistochemical phenotype, molecular changes, differential diagnosis and prognosis of eosinophilic solid and cystic renal cell carcinoma (ESC RCC). Methods: A total of 15 cases were selected from 2005 to 2019 at Nanjing Jinling Hospital,Nanjing University School of Medicine for clinicopathological and immunohistochemical analysis, 10 of which were subject to cancer-associated mutation analysis using targeted next-generation sequencing (NGS) panel. A literature review was also performed. Results: The patients′ ages ranged from 15 to 68 years (mean, 33 years). The male-to-female ratio was 1.1∶1.0. During a mean follow-up of 22 months, none of the patients developed tumor recurrence, progression or metastasis. Histologically, the tumors typically demonstrated solid and cystic architectures and the neoplastic cells contained voluminous eosinophilic cytoplasm with prominent granular cytoplasmic stippling. Immunohistochemically, tumor cells in all cases were immunoreactive for CK20. Signal pathway related protein mTOR and S6 were positive in 14/15 and 6/15 cases, respectively. Cathepsin K, Melan A and HMB45 were at least focally positive in 12/15, 6/15 and 2/15 cases, respectively. CK7 and CD10 showed focal immunostain positivity in some cases, while TFE3, TFEB, CA9 and CD117 were negative in all cases. NGS demonstrated TSC1/TSC2 mutations in all tested cases (10/10). Conclusions ESC RCC is a rare tumor that tends to occur in young patients with an indolent behavior. Diagnosis can be established by its distinct clinical and histopathologic findings, immunohistochemical phenotype and molecular genetics. The tumor may be considered as a new subtype of RCC.

study the clinicopathological features, immunohistochemical phenotype, molecular changes, differential diagnosis and prognosis of eosinophilic solid and cystic renal cell carcinoma (ESC RCC). Methods A total of 15 cases were selected from 2005 to 2019 at Nanjing Jinling Hospital,Nanjing University School of Medicine for clinicopathological and immunohistochemical analysis, 10 of which were subject to cancer?associated mutation analysis using targeted next?generation sequencing (NGS) panel. A literature review was also performed. Results The patients′ ages ranged from 15 to 68 years (mean, 33 years). The male?to?female ratio was 1.1∶1.0. During a mean follow?up of 22 months, none of the patients developed tumor recurrence, progression or metastasis. Histologically, the tumors typically demonstrated solid and cystic architectures and the neoplastic cells contained voluminous eosinophilic cytoplasm with prominent granular cytoplasmic stippling. Immunohistochemically, tumor cells in all cases were immunoreactive for CK20. Signal pathway related protein Mtor and S6 were positive in 14/15 and 6/15 cases, respectively. Cathepsin K, Melan A and HMB45 were at least focally positive in 12/15, 6/15 and 2/15 cases, respectively. CK7 and CD10 showed focal immunostain positivity in some cases, while TFE3, TFEB, CA9 and CD117 were negative in all cases. NGS demonstrated TSC1/TSC2 mutations in all tested cases (10/10). Conclusions ESC RCC is a rare tumor that tends to occur in young patients with an indolent behavior. Diagnosis can be established by its distinct clinical and histopathologic findings, immunohistochemical phenotype and molecular genetics. The tumor may be considered as a new subtype of RCC.

Objective: To study the molecular features of metanephric adenoma (MA) and discuss their values in differential diagnosis. Methods: BRAF V600E immunohistochemistry (IHC) using the mutation-specific VE1 monoclonal antibody and Sanger sequencing of BRAF mutations were performed on 21 MAs, 16 epithelial-predominant Wilms tumors (e-WT) and 20 the solid variant of papillary renal cell carcinomas (s-PRCC) respectively. p16 protein was detected by IHC also. Fluorescence in situ hybridization (FISH) analyses using centromeric probes for chromosome 7 and 17 were performed on the three renal tumors in parallel. Results: Fourteen (14/21, 66.7%) of 21 MA cases demonstrated diffuse, moderate to strong cytoplasmic BRAF V600E IHC staining and the BRAF V600E protein expression was detected in 2 (2/16) of 16 e-WT cases for the first time, whereas all s-PRCCs were negative (P<0.05). All cases (including 14 MAs and 2 e-WTs) with diffuse, moderate to strong cytoplasmic BRAF V600E IHC staining were confirmed to harbor BRAF V600E missense mutations using Sanger sequencing, and no BRAF mutations were detected in cases with negative BRAF V600E protein expression. One case (1/21, 4.8%) showed trisomy of chromosome 7 alone, and another one (1/21, 4.8%) showed trisomy of chromosome 17 alone in 21 MAs. Two cases (2/16) of 16 e-WTs showed trisomy of chromosome 17 alone. In 20 s-PRCCs, trisomy of chromosomes 7 alone was reported in 2 cases (2/20), trisomy of chromosome 17 alone in 3 cases (3/20) and trisomy of chromosome 7 and 17 in 14 cases (14/20). The total positive rates of trisomy of chromosome 7 and/or 17 in MAs, e-WTs and s-PRCCs were 9.6% (2/21), 2/16 and 95.0% (19/20). p16 protein was positive in 81.0% (17/21) MAs, whereas the positive rates in e-WTs and s-PRCCs were 2/16 and 5.0% (1/20). Conclusions Most MAs harbor BRAF V600E mutations, and MAs lack the gains of chromosome 7 and 17 that are characteristic of papillary renal cell carcinoma. These molecular features can be used to distinguish MA from its mimics. BRAF V600E IHC using the mutation-specific VE1 monoclonal antibody provides an effective method in BRAF V600E mutations detection of renal tumors. p16 is overexpressed in MA, and the finding suggests that the low proliferative rate of the tumor might be attributed to BRAF V600E-induced senescence mediated by p16.

Objective: To investigate the prevalence of biting pencils among pupils living in Harbin, Guangzhou, and Beijing and to compare the differences among these cases. Methods: Stratified sampling method was used to select four elementary schools in Harbin and Guangzhou from April 2015 to April 2016. Firstly, Simple random sampling method was used in every grade (grade 1-grade 5) to select 3 or 4 classes (71 classes in total).After the sample selection, questionnaire surveys were conducted among pupils and their guardians (anyone of their guardians) who belonged to these classes. Secondly, the study extracted part of these pupils to conduct a field survey. Every school was classified by grade, and every grade adopted the method of random sampling to select one classes (20 classes in total). Meanwhile, the study randomly selected pupils from 10 classes in 2 elementary schools in Beijing. All together, 1 627 pupils participated in the field survey. The questionnaire included general information about the students and their guardians, the situation of biting pencils, the awareness of the harm of biting pencils, etc.; the field survey considered if participates' pencils have tooth marks and the severity of the marks, etc. χ² was applied to test and compare the differences among pupils of different genders and different cities. The comparison focused on the proportion of students who bited pencils, the proportion of pencils with tooth marks and the proportion of students and guardians already awared of the harm of biting pencils, etc. Results: The number of the valid questionnaires in Harbin and Guangzhou were 1 842, and 1 210, respectively. The occurrence rate of pupils biting pencils in Harbin (18.0% (333/1 842)) was higher than that in Guangzhou (11.3% (137/1 210)) (χ²=29.16, P=0.001). Specifically, in Harbin, the rate of boys biting pencils was 21.9% (212/965), which was higher than girls (13.8% (121/877)) (χ²=27.04, P=0.001). Similarly, in Guangzhou, the rate of boys biting pencils was 14.5% (92/632), which was also higher than girls (7.7% (45/578)) (χ²=15.34, P=0.001). The awareness rate of the harm of biting pencils among students from these two cities were 88.5% (1 611/1 819), and 90.8% (1 098/1 208), respectively, and the difference was statistically significant as well (χ²=4.39, P= 0.020). Compared with these data, the awareness rate of the harm of biting pencils among guardians from these two cities were 74.7% (1 339/1 791), and 79.4% (832/1 047), respectively as well as the statistically significant difference appeared (χ²=9.83, P=0.007). The result of field survey showed the rate of tooth-marked pencils in Harbin, Guangzhou and Beijing was 30.5% (187/613), 14.8% (79/534), and 28.3% (136/480), respectively. The difference was also statistically significant (χ²=42.68, P=0.001). The degree of tooth marks was mainly mild, while the percentage of mild degree in Guangzhou (54.4%(43/79)) and Beijing (41.2% (56/136)) was apparently higher than that of Harbin (39.0% (73/187)). The difference was not statistically significant (χ²=7.01, P=0.136). Conclusion The behavior of biting pencils existed universally among pupils in Harbin, Guangzhou, and Beijing , which the situation of pupils biting pencils in Harbin and Beijing was more serious than that in Guangzhou. Pupils, parents and teachers should pay attention to such a behavior.

Objective: To study the clinicopathologic characteristics and diagnostic criteria of primary mediastinal B-cell lymphoma (PMBL), and to distinguish PMBL from classic Hodgkin lymphoma(CHL) and systemic diffuse large B-cell lymphoma(DLBCL). Methods: The clinical features, histologic findings, results of immunohistochemical study and prgnosis in 27 PMBL cases were analyzed, with review of literature. Results: The age of patients ranged from 19 to 82 years (median age 34 years). All cases were located in the mediastinum and frequently accompanied by superior vein cava syndrome. Histologically, the tumor cells were pleomorphic and diffusely distributed. Clear cytoplasm and spindle tumor cells were seen in some cases. Varying amount of sclerosing stroma with collagen deposition was seen.Immunohistochemical study showed that the tumor cells were positive for CD20(100%, 27/27), CD30 (64.0%, 16/25), CD23 (77.3%, 17/22) and p63 (16/19). Clonal B cell gene rearrangement was seen. Conclusions PMBL is a subtype of diffuse large B-cell lymphoma with various histomorphology. Immunohistochemistry can help to confirm the diagnosis, and the prognosis is better than diffuse large B cell lymphoma, not otherwise specified.

Objective To study the expression of cadherin 17 ( CDH17 ) in metanephric adenoma ( MA ) , and to explore the value of CDH 17 in the diagnosis of metanephric adenoma.Methods Immunohistochemical EnVision method was used to detect the expression of CDH 17, WT1, CD57, P504S and EMA in 21 cases of MAs, 16 epithelial-predominant Wilms tumors ( e-WT), and 20 solid variant of papillary renal cell carcinomas ( s-PRCC).The expression of CDH17 was also examined in other common renal epithelial tumors , including 10 cases of clear cell renal cell carcinomas ( CCRCC ) , 10 chromophobe renal cell carcinomas ( CHRCC), and 10 oncocytomas.Results Twenty (95.2%) of 21 cases of MAs demonstrated membranous CDH 17 immunoreactivity in all components ( acinar , tubular , and papillary ) , whereas only 1 (1/16) e-WT was positive for CDH17 and all s-PRCCs were negative ( P<0.05).WT1 was negative in s-PRCC and was positive in all cases of e-WT ( 16/16 ) and MA ( 100%,21/21 ).All MAs (100%) were strongly positive for CD57;however, this marker was also positive in 13 (13/16) e-WTs and 9 (45.0%,9/20) s-PRCCs.P504S was strongly positive in all s-PRCCs (100%), but reactivity was seen in 3 (14.3%,3/21) MAs and all e-WTs were negative.The positive rates of EMA in MAs, e-WTs and s-PRCCs were 19.0%(4/21),14/16 and 17/20, respectively.The sensitivity and specificity of CDH17 in the diagnosis of MA were 95% and 97%.CDH17 was negative in all cases of CCRCC , CHRCC and oncocytoma.Conclusions CDH17 is a highly sensitive and specific marker for MA and should be considered in the immunohistochemistry panel for distinguishing MA from its mimics and other common renal epithelial tumors.

OBJECTIVETo study the clinicopathologic features, immunophenotype, differential diagnosis and prognosis of renal cell carcinoma (RCC) associated with t(6;11)(p21.2;q13)/MALAT1-TFEB gene fusion.

METHODSA total of 9 cases of such rare tumor were selected for clinicopathologic, immunohistochemical and molecular analysis, with review of literature.

RESULTSThe age of the patients ranged from 21 to 42 years (mean=31.3 years). The patients included four men and five women. Histologically, 4 of the 9 cases studied showed classic morphologic features of TFEB RCC, with hyaline material, pigments and psammoma bodies frequently identified. The remaining 5 cases demonstrated uncommon morphology, mimicking perivascular epithelioid cell neoplasm, clear cell RCC, chromophobe RCC or papillary RCC. Immunohistochemical study showed that TFEB and vimentin were positive in all cases. Most of the tumors studied also expressed Ksp-cadherin, E-cadherin, CD117, HMB45, Melan A and Cathepsin K. CKpan showed immunostaining in only 1 case. The staining for TFE3, CD10 and CK7 were all negative. TFEB gene rearrangement was detected in all the 9 cases studied using fluorescence in-situ hybridization. MALAT1-TFEB fusion gene was identified in 2 cases by polymerase chain reaction and direct sequencing. TFEB RCC seemed to be an indolent tumor. During a mean follow-up of 31 months, none developed tumor recurrence, progression, or metastasis.

CONCLUSIONSTFEB fusion-associated RCC is a rare neoplasm, tends to occur in young age group and carries an indolent behavior. Diagnosis relies on clinicopathologic findings and immunohistochemical analysis. TFEB break-apart FISH assay is a reliable tool in confirming the diagnosis.

Adult ; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ; genetics ; Carcinoma, Renal Cell ; genetics ; pathology ; Chromosomes, Human, Pair 11 ; Chromosomes, Human, Pair 6 ; Diagnosis, Differential ; Female ; Gene Fusion ; Gene Rearrangement ; Genes, Neoplasm ; Humans ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Kidney Neoplasms ; genetics ; pathology ; Male ; Prognosis ; RNA, Long Noncoding ; genetics ; Translocation, Genetic ; Young Adult

OBJECTIVETo study the clinicopathologic characteristics of primary renal hemangioblastoma.

METHODSThe morphologic features, immunophenotype and molecular findings of 3 cases of primary renal hemangioblastoma were studied, with review of literature.

RESULTSThe age of patients ranged from 43 to 57 years. There were 2 women and a man. The patients often presented with renal mass. Histologically, the tumors were surrounded by thick fibrous capsule and composed of epithelioid or spindle cells. Two cases had a prominent stromal component and the other one was rich in capillary network. Lipid vacuoles were observed in all cases. Features of hemorrhage were demonstrated in 2 cases. Capsular invasion and necrosis were seen in 1 case. Immunohistochemical study showed that the stromal cells were positive for alpha-inhibin (3/3), S-100 protein (3/3), EGFR (2/2), PAX-2 (2/2), PAX-8 (2/2) and CA9 (2/2) but negative for CKpan (2/2) and HMB45 (2/2). Focal membranous staining for CD10 (3/3) was noted. No VHL gene mutations or chromosome 3p deletion were detected in the 2 cases studied.

CONCLUSIONSRenal hemangioblastoma shows distinctive morphologic appearance with a wide range of variation. The unexpected positive staining for PAX-2, PAX-8 and CD10 in renal hemangioblastoma needs to be aware. Immunohistochemical study may be helpful in differential diagnosis of these renal tumors.