Objective To summarize the pathological morphological features, diagnosis, and differential diagnosis of adult-onset Still disease (AOSD), and to improve clinical understanding of the disease. Methods A retrospective analysis was conducted on the morphological characteristics, immunophenotypes, and molecular detection results of lymph node biopsies from three AOSD patients. Results Case 1: lymph node biopsy tissue showed significant lymphoid follicular hyperplasia, accompanied by parafollicular hyperplasia; the germinal centers exhibited a starry-sky phenomenon, with no obvious histiocyte proliferation foci, plasma cells, or neutrophils; immunohistochemical staining showed that CD3 and CD5 T lymphocyte were positive in the paracortical area, CD20 and CD79α markers showed that B lymphocytes were mainly located in the follicular area, CD21 follicular dendritic cells and CD68 histiocytes were positive. Case 2: lymph node puncture tissue showed paracortical hyperplasia, a decrease in the number of follicles, and a reduction of follicular volume; there were no obvious histiocyte proliferation foci, plasma cells, or neutrophils; immunohistochemical staining showed positive CD3, CD5 T lymphocytes in the paracortical area, and CD20, CD79α B lymphocytes in the follicular region. Case 3: lymph node puncture tissue showed partial preservation of the normal lymph node structure, the paracortical area was diffusely proliferated, and the histiocyte hyperplasia was patchy with partial necrosis, and obvious nuclear debris, scattered plasma cells and eosinophils can be seen and no obvious neutrophil infiltration in the necrotic area; immunohistochemical staining of case 3 showed that CD21 and CD23 follicular dendritic cells were positive, and Bcl-2, Bcl-6, CD3, CD5, CD20, CD79α, and multiple myeloma protein 1 (MUM1) were positively expressed in some lymphocytes; the Ki-67 proliferation index was high, approximately 70%; a few plasma cells were positive for CD138, with individual cells positive for CD1α; CD10 and CyclinD1 were negative; histiocytes were positive for myeloperoxidase (MPO); and EBER was negative for in situ hybridization. The results of TCR gene rearrangement and IG gene rearrangement in the three cases were negative. Conclusion The immunophenotype of AOSD is diversity, and its dignosis depends on the clinical and pathological morphological features and immunophenotype, excluding infectious diseases, malignant tumors and lymphoma, etc.

Objective To explore the expression and clinical significance of Yes-associated protein 1(YAP1)in esophageal squamous cell carcinoma.Methods Immunohistochemical method was used to detect YAP1 expression in 439 cases of esophageal squamous cell carcinoma.The differences of YAP1 expression and clinical parameters were analyzed between YAP1 positive group and YAP1 negative group.Kaplan-Meier curve was used to analyze the influence of YAP1 expression on survival of patients.Results The positive rate of YAP1 in esophageal squamous cell carcinoma was 30.52% .The tumor invasion was deeper in YAP1 positive group(P＜0.001).Kaplan-Meier survival analysis showed that YAP1 positive patients had longer disease-free survival(DFS)and overall survival(OS)among patients surviving longer than 30 months(P＜0.05).The multivariate Cox regression analysis showed that the invasion depth of tumor was an independent factor affecting DFS(HR=1.371,95% CI 0.993-1.894,P=0.035)and OS(HR=1.489,95% CI 1.066-2.080,P=0.020).Conclusions YAP1 has a certain percentage of positive rate in esophageal squamous cell carcinoma;for patients with survival longer than 30 months,YAP1 positive indicates a better prognosis.

Objective:To investigate the biological behavior spectrum of platelet-derived growth factor alpha receptor (PDGFRA)-mutant gastrointestinal stromal tumor (GIST), and to compare the clinical values of the Zhongshan method of benign and malignant evaluation with the modified National Institutes of Health (NIH) risk stratification.Methods:A total of 119 cases of GIST with PDGFRA mutation who underwent surgical resection at Zhongshan Hospital, Fudan University from 2009 to 2020 were collected. The clinicopathological data, follow-up records, and subsequent treatment were reviewed and analyzed statistically.Results:There were 79 males and 40 females. The patients ranged in age from 25 to 80 years, with a median age of 60 years. Among them, 115 patients were followed up for 1-154 months, and 13 patients progressed to disease. The 5-year disease-free survival (DFS) and overall survival (OS) were 90.1% and 94.1%, respectively. According to the modified NIH risk stratification, 8 cases, 32 cases, 38 cases, and 35 cases were very-low risk, low risk, intermediate risk, and high risk, and 5-year DFS were 100.0%, 95.6%, 94.3%, and 80.5%, respectively. There was no significant difference in prognosis among the non-high risk groups, only the difference between high risk and non-high risk groups was significant ( P=0.029). However, the 5-year OS was 100.0%, 100.0%, 95.0% and 89.0%, and there was no difference ( P=0.221). According to the benign and malignant evaluation Zhongshan method, 43 cases were non-malignant (37.4%), 56 cases were low-grade malignant (48.7%), 9 cases were moderately malignant (7.8%), and 7 cases were highly malignant (6.1%). The 5-year DFS were 100.0%, 91.7%, 77.8%, 38.1%, and the difference was significant ( P<0.001). The 5-year OS were 100.0%, 97.5%, 77.8%, 66.7%, the difference was significant ( P<0.001). Conclusions:GIST with PDGFRA gene mutation shows a broad range of biological behavior, ranging from benign to highly malignant. According to the Zhongshan method, non-malignant and low-grade malignant tumors are common, the prognosis after surgery is good, while the fewer medium-high malignant tumors showed poor prognosis after surgical resection. The overall biological behavior of this type of GIST is relatively inert, which is due to the low proportion of medium-high malignant GIST. The modified NIH risk stratification may not be effective in risk stratification for PDGFRA mutant GIST.

Objective:To investigate the clinicopathological features and treatment of gastric alpha-fetoprotein (AFP)-producing adenocarcinoma with SWI/SNF complex deletion.Methods:Four cases of gastric AFP-producing adenocarcinoma with SWI/SNF complex deletion diagnosed in Zhongshan Hospital of Fudan University from January 2021 to December 2022 were collected, and their histomorphological characteristics, immunohistochemical (IHC), in situ hybridization of Epstein-Barr virus-encoded RNA (EBER), next-generation sequencing results, clinicopathological features and treatment were summarized, and literature review was conducted.Results:Among the 4 patients, there were three males and one female. They presented with abdominal pain, belching and melena. Serum AFP was significantly elevated in three patients, and endoscopy showed ulcerative lesions. Microscopically, the tumor cells showed mainly diffuse flaky or nest-like growth and typical characteristics of hepatoid adenocarcinoma. In two cases there were adenoid growth, and the tumor cells in these areas possessed clear cytoplasm, suggesting enteroblastic differentiation. The tumor cell nuclei were pleomorphic with large nucleoli and brisk mitoses. The IHC results showed that the tumor cells expressed AFP, GPC3 and SALL4, and there was retained expression of broad-spectrum keratin (CKpan) and E-cadherin. IHC detection of SWI/SNF complex subunits, namely INI1 (SMARCB1), BRG1 (SMARCA4), BRM (SMARCA2), ARID1A protein was performed. In all four cases the hepatoid adenocarcinoma region and enteroblastic differentiation region showed SMARCA2 deletion, and one case with enteroblastic differentiation also showed ARID1A deletion. SMARCB1 and SMARCA4 deletions were not seen. All the four cases were diffusely positive for p53 protein, and the Ki-67 proliferation index was 80%-90%. There were no mismatch repair deletion detected; one cases showed HER2 was strongly positive (3+), and EBER was negative. None of the four cases had mutations in the SWI/SNF complex-related subunits detected by next-generation sequencing. Among the four patients, two underwent palliative surgery due to distant metastasis at the time of surgery, two underwent radical resection. Postoperative adjuvant chemotherapy was given to three patients.Conclusions:AFP-producing adenocarcinoma is a rare subtype of gastric cancer, which can be combined with SWI/SNF complex deletion, and the pathomorphological manifestations are different from the classical SWI/SNF complex deletion of undifferentiated carcinoma with rhabdoid phenotype.

Purpose To investigate the expression of fork-head box protein A1(FOXA1)in esophageal squamous cell car-cinoma(ESCC)and its association with clinicopathologic char-acteristics and prognosis.Methods Immunohistochemistry was used to detect FOXA1 protein expression in 532 cases of esopha-geal squamous cell carcinoma.The correlation between FOXA1 protein expression and clinicopathologic features and prognosis of patients was analyzed.Results In 532 cases of esophageal squamous cell carcinoma,183 cases overexpressed FOXA1 pro-tein(34.4％).FOXA1 overexpression was associated with ES-CC vascular infiltration(P=0.032),poorly differentiation(P=0.032),and tumor size(P＜0.001).The overall survival(OS)and disease free survival(DFS)of patients with stage Ⅰ+Ⅱ esophageal squamous cell carcinoma with high FOXA1 ex-pression tended to be poor(OS:P=0.094;DFS:P=0.107).In ESCC patients with survival longer than 24 months,the high FOXA1 expression group had significantly shorter OS and DFS(OS:P=0.048;DFS:P=0.047).Multivariate survival anal-ysis showed that the depth of tumor invasion was an independent prognostic factor affecting the prognosis of esophageal squamous cell carcinoma.Conclusion FOXA1 is overexpressed in e-sophageal squamous cell carcinoma,and its high expression is related to tumor size,vascular infiltration and poorly differentia-tion.Patients with high FOXA1 expression tended to have poor prognosis in OS and DFS.When OS and DFS≥24 months,high FOXA1 expression may be used as a reference indicator for poor prognosis in ESCC patients.

Objective To investigate the effects of KRAS mutation isoforms on tumor regression grade(TRG)of rectal cancer received neoadjuvant therapy.Methods The clinicopathologic data of patients with locally advanced and metastatic rectal cancer(stage Ⅲ-Ⅳ)who underwent radical tumor resection after neoadjuvant therapy were collected.The correlations between the mutated subtypes of KRAS and TRG as well as the clinicopathological features were analyzed.Results A total of 95 patients were enrolled,including 55 patients with poor tumor regression.The incidences of G12V mutation in exon 2 and A146 mutation in exon 4 of the KRAS gene were higher in the group with poor tumor regression than those in the significant tumor regression group(P＜0.05).In patients with G12D mutation of KRAS gene,the histological grade of tumor in poor tumor regression was higher than that in significant tumor regression group(P=0.027).In patients with poor tumor regression,the levels of CD8+,PD-1+T-lymphocyte infiltration were higher in G12D mutation subgroup than those in G12V mutation and G13D mutation subgroups(P＜0.05).Conclusions KRAS G12V mutation and A146 mutation suggest poor neoadjuvant therapy effect for rectal cancer;for patients with KRAS G12D mutation and poor tumor regression,the potential beneficiary for immunotherapy would be screened by detecting CD8+and PD-1+T-lymphocyte infiltration.

Purpose To investigate the clinicopathologic features,molecular changes,treatment and prognosis of pulmo-nary artery intimal sarcoma.Methods Ten cases of pulmonary artery intimal sarcoma were collected and the clinical features analyzed,by using HE,immunohistochemistry EnVision meth-od,FISH,and review of relevant literature.Results There were 4 males and 6 females,with a male to female ratio of 1∶1.5.The patients were 33-75 years old with an average age of 55.7 years.The main clinical symptoms were chest tightness,shortness of breath(6/10),chest pain(5/10)and cough(3/10),hemoptysis(2/10),syncope(1/10),heart murmur(1/10).1 patient had a history of bilateral breast cancer,bilateral papillary thyroid carcinoma and invasive lung adenocarcinoma,1 patient had bilateral breast cancer and 1 patient had pulmonary embolism and cardiac myxoma.Preoperative imaging showed pulmonary embolism or lung tumor.Histological morphology showed that the tumor cells were fusiform or epithelioid,with ob-vious atypia.Some tumors differentiated into rhabdomyosarco-ma,angiosarcoma and leiomyosarcoma,and giant cells were seen in 2 cases.The tumor lacked specific immune markers,and the tumor cells expressed vimentin,Fli-1,SMA,MyogD1,Myoglobin,BCL-2,ERG,etc.Ki-67 proliferation index was a-bout 30％-70％.Fluorescence in situ hybridization was used to detect MDM2(4/5)and CDK4(1/1).All cases received surgical treatment,7 cases were followed up from 1 month to 17 months,and 4 cases of them had recurrence or distant metasta-sis.Conclusion Pulmonary artery intimal sarcoma is rare,without specific immune markers and with complicated gene changes.There is no standard treatment,and the prognosis is poor.

For locally advanced esophageal squamous cell carcinoma (ESCC), neoadjuvant therapy combined with surgery has become the standard treatment schedule. The application of immunotherapy, represented by programmed death-1 and programmed death-ligand 1 inhibitors, has injected new vitality into neoadjuvant therapy for ESCC. At present, a large number of clinical trials are being carried out and explored, which brings new challenges to the diagnosis of clinical pathologists. Combined with the latest researches at home and abroad and clinical diagnosis problems, the authors summarize the relevant problems and progress of pathological evaluation before and after neoadjuvant immunotherapy from the perspective of pathology, in order to improve the level of clinical pathological diagnosis and provide reference for further optimizing the comprehensive treat-ment strategy.

Objective:To investigate MAML2 gene rearrangement, gene fusion patterns, and the clinicopathological characteristics of primary pulmonary mucoepidermoid carcinoma (PMEC).Methods:Forty-six cases of primary PMEC from Fudan University Zhongshan Hospital and Fudan University Shanghai Cancer Center between 2017 and 2020 were collected. MAML2 gene rearrangement in all cases was detected by fluorescence in situ hybridization (FISH). In 20 cases, MAML2 fusion patterns were detected by targeted RNA sequencing (RNAseq). The relationship between MAML2 gene rearrangement, fusion patterns, clinicopathological characteristics, and prognosis was analyzed.Results:The average age of PMEC patients was 41 years (range 15-71 years); the ratio of male to female was about 1.1 ∶ 1.0. Most PMECs were low grade in histopathology with an early clinical stage (stageⅠ-Ⅱ).The overall positive rate of MAML2 gene rearrangement detected by FISH was about 80.4% (37/46), and the rate was higher in low-grade PMEC (91.7%, 33/36). Of the 20 cases detected by RNAseq, all the 19 FISH positive cases showed gene fusion, mainly CRTC1-MAML2 fusion (16/19), the other three cases showed CRTC3-MAML2 fusion (3/19), the break point of all the fusion patterns was CRTC1/3 (exon 1)-MAML2 (exon 2); No gene fusion was detected in the single FISH negative case; Compared with the MAML2 FISH negative patients, the PMECs carrying CRTC1-MAML2 fusion were more commonly found in patients age ≤ 40 years, maximum tumor diameter ≤ 2 cm, low histopathological grade and early clinical stage (all P<0.05); The three PMECs carrying CRTC3-MAML2 fusion gene were all female with early clinical stage; Univariate analysis showed that MAML2 gene rearrangement/fusion, onset age ≤ 40 years old, smaller tumor size, low histopathological grade, early clinical stage, no metastasis at diagnosis and surgical treatment were significantly correlated with overall survival ( P<0.05), but Cox regression analysis suggested that none of the above indicators were the independent prognostic factors for the survival of PMEC. Conclusions:The high incidence of MAML2 gene rearrangement in PMEC suggests that it is an important molecular diagnostic marker of PMEC. RNAseq confirms that CRTC1/3-MAML2 is the main fusion pattern in PMEC, suggesting that MAML2 fusion transcription may be an important driving factor of PMEC. MAML2 rearrangement/fusion and related clinicopathological characteristics are associated with good prognosis.

Objective:To compare the histologic features of immune-mediated hepatitis (IMH) due to immune checkpoint inhibitors (ICIs) monotherapy and combined ICIs anti-angiogenesis tyrosine kinases (TKIs) targeted therapy.Methods:Twenty-one IMH patients who had liver biopsy during ICIs treatment in Zhongshan Hospital of Fudan University from 2015 to 2019 were included. Among them, ten were treated with ICIs monotherapy, and 11 were treated with combined ICIs and anti-angiogenesis targeted therapy. The histologic features of IMH were assessed by HE staining and PD-L1/2 was evaluated by immunohistochemical staining.Results:Patients treated with monotherapy ICIs presented with different levels of lobular hepatitis and portal inflammation. Besides, there were also cholangitis, endothelialitis, Kupffer cells activation and peliosisi hepatitis. Eight cases (8/10) showed mild and two cases (2/10) showed moderate hepatic injury. As for patients receiving combined ICIs and TKIs therapy, the extent of IMH was more severe, with four cases (4/11) showing moderate-severe liver injury, with confluent or bridging necrosis, portal inflammation, cholangitis, interface hepatitis. Among these, one patient developed acute severe hepatitis with massive hepatocyte necrosis and died of multisystem dysfunction. In those cases with severe liver injury, many CD8 positive lymphocytes aggregated in the portal area and hepatic sinusoid, and PD-L1 was expressed in many endothelial cells. There were both 2 cases of death in ICIs monotherapy and combination therapy group. Among the latter group, 1 patient developed acute severe hepatitis with massive hepatocyte necrosis and died of multisystem dysfunction.Conclusion:Compared with ICIs monotherapy, combined ICIs and anti-angiogenesis targeted TKIs therapy may cause overlapping hepatic injury, leading to severe IMH.