Objective:To explore the consistency of claudin 18.2 immunohistochemistry (IHC) using 4 different clone antibodies in gastric adenocarcinoma.Methods:A total of 226 gastric adenocarcinomas diagnosed and treated at the Drum Tower Hospital Affiliated to Nanjing University Medical College between January 2022 to March 2023 were included in this study. The cohort consisted of 165 males and 61 females, with a mean age of (61.3±12.1) years. Tumor tissues from radical resection specimens were collected for tissue microarrays. IHC detection of claudin 18.2 was performed using the EnVision method, utilizing 4 clones of antibody: OTIR157B5, 43-14A, EPR19202 and D313D22. The results were interpreted based on both the intensity of staining on tumor cell membranes and the percentage of positive tumor cells relative to the total tumor cells.Results:The positive cutoff value was set as moderately to strongly linear membrane staining in ≥75% of all viable invasive tumor cells, and clone OTIR157B5 demonstrated the highest positive expression rate at 52.2% (118/226). Additionally, the clones OTIR157B5, 43-14A, and EPR19202 were consistently and strongly positive, with all agreement rates of Cohen κ exceeding 0.8. In gastric adenocarcinoma and its three Lauren subtypes, OTIR157B5 exhibited clear membranous localization.Conclusions:Clone OTIR157B5 of claudin 18.2 antibody shows the highest rate of moderately to strongly linear membrane-positive staining, accounting for ≥75% of all viable invasive tumor cells, and clones 43-14A and EPR19202 show strong consistency and high sensitivity.

Objective:To investigate the clinicopathological characteristics of type 2 autoimmune pancreatitis (AIP) and to explore its relationship with inflammatory bowel disease (IBD).Methods:AIP cases confirmed by pathology in the First Affiliated Hospital of Zhejiang University School of Medicine from 2009 to 2024 were collected. According to the International Consensus Diagnostic Criteria (ICDC) for AIP, 11 patients were identified as histological level 1 (definite) or level 2 (probable) type 2 AIP. Their clinical manifestations, laboratory test results, imaging features, and histopathological characteristics were analyzed, and a follow-up was conducted. Meanwhile, 130 patients with type 1 AIP diagnosed in our hospital during the same period were selected as control group.Results:Among 141 AIP patients, 11 cases (7.8%, 11/141) were diagnosed with type 2 AIP, including 7 cases of histologically level 1 and 4 cases of level 2. There were 10 male patients and 1 female patient, with a median age of 37(31,46) years (range: 25-47 years). Three patients were complicated with ulcerative colitis (UC). Compared with type 1 AIP patients, type 2 AIP patients were younger, often presented with acute pancreatitis or abdominal pain as the initial symptom, and had a close association with IBD ( P<0.05). Laboratory tests showed that only 1 patient had slightly elevated serum IgG4, while the other 10 patients had normal serum IgG4 levels. Serum CA19-9 was elevated in 8 patients, and the percentage of peripheral blood neutrophils was increased in 9 patients. Imaging findings revealed diffuse pancreatic enlargement in 8 patients and localized enlargement in 3 patients (2 cases in the pancreatic head and 1 case in the pancreatic body-tail). Magnetic resonance cholangiopancreatography (MRCP) showed main pancreatic duct stenosis in 5 cases (5/7). Histopathological features included 7 cases of level 1 type 2 AIP that showed neutrophilic infiltration in the pancreatic duct epithelium and massive neutrophilic infiltration between the acini. Immunohistochemistry showed that only 1 case had <5 IgG4-positive plasma cells per high-power field (HPF), while the other 10 cases were negative. All 11 patients with type 2 AIP received steroid therapy, and no recurrence was observed during the follow-up period of 5 to 174 months. Conclusions:Type 2 AIP has unique clinicopathological characteristics. It is more commonly found in young patients and often presents with manifestations similar to acute pancreatitis. Histologically, neutrophilic infiltration in the ductal epithelium is the common feature. Type 2 AIP is closely associated with IBD, especially UC.

Objective:To investigate the clinicopathological characteristics and genetic alterations of undifferentiated embryonal sarcoma of the liver (UESL).Methods:Three cases of UESL diagnosed in the Department of Pathology, the Third Affiliated Hospital of Sun Yat-sen University from 2020 to 2023 were retrospectively collected. The clinical, histomorphological, immunohistochemical, and genetic profiles were reviewed and analyzed.Results:The cohort comprised of three patients, including one male and two females, aged 7, 9, and 15 years, respectively. Tumor locations were in the right lobe of the liver in two cases, and in both the right and left lobes in one case. One case exhibited tumor rupture with hemorrhage. Gross examination revealed solid tumors in gray-red fleshy appearance, with areas of hemorrhage and necrosis. Microscopically, the tumor was composed of irregularly shaped spindle and polygonal cells arranged in bundles or sheets with varying density, scattered within a myxoid matrix containing giant tumor cells and eosinophilic globules. The tumor cells were positive for Vimentin, CD56, CD68, and bcl-2, with a Ki-67 index of 30%-80%. INI1 expression was retained, while p53 exhibited a mutant pattern. CKpan, CK7, CK19, EMA, HepPar-1, Arginase-1, AFP, CD34, S-100, Myogenin, and MyoD1 were negative. All three cases harbored TP53 missense mutations. Case 1 also showed MDM2 copy number amplification (class Ⅰ mutation), and case 2 exhibited a frameshift mutation in exon 10 of TSC2 (class Ⅱ mutation). Additionally, several class Ⅲ mutations were identified in all three cases. Germline testing for tumor-related genetic variants in case 2 revealed a missense mutation in exon 12 of DICER1, an in-frame insertion mutation in exon 8 of MSH2, and a missense mutation in exon 30 of TSC2.Conclusion:UESL is a rare malignant mesenchymal tumor of the liver, predominantly affecting children, with distinctive clinicopathological features and genetic alterations. TP53 mutations may play a key role in the pathogenesis of this tumor.

Objective:To investigate the clinicopathological and molecular genetic characteristics of diffuse gliomas with the features of polymorphous low-grade neuroepithelial tumor of the young (PLNTY) and their prognostic values.Methods:A retrospective analysis was performed on 14 cases of diffuse gliomas with PLNTY features diagnosed at the First Affiliated Hospital of Fujian Medical University, Fuzhou, China from June 2020 to August 2024. Their clinicopathological characteristics were examined, and their molecular genetic and epigenetic features were assessed using next-generation sequencing (NGS) and methylation analysis. Factors influencing prognosis were also analyzed.Results:Among the 14 patients, there were 8 males and 6 females, aged 3-62 years, median 29 (9, 50) years. All cases were initially diagnosed as low-grade diffuse gliomas histologically but exhibited the histological and immunohistochemical features of PLNTY. At the molecular level, all cases showed molecular abnormalities involving the mitogen-activated protein kinase pathway, including 5 cases with FGFR3-TACC3 (F3T3) fusion, 3 cases with FGFR2 fusion, 5 cases with BRAF V600E mutation, and 1 case with FGFR1 mutation. Among them, TERT promoter mutations were frequently observed in tumors with F3T3 fusion (5/5), while NCOR2 in-frame insertion mutations were prominent in tumors with non-F3T3 fusions. Clinical follow-up showed recurrence in 3 cases, all of which had F3T3 fusion and concurrent TERT promoter mutations. Prognostic analysis confirmed that F3T3 fusion with concurrent TERT promoter mutation was associated with poor prognosis.Conclusions:Diffuse gliomas with PLNTY features exhibit heterogeneity in clinicopathology and molecular genetics, with FGFR3/FGFR2 fusions and BRAF/FGFR1 mutations as the most common molecular alteration. They often have concurrent F3T3 fusion and TERT promoter mutations, which are related to poor prognosis. The possibility of molecular glioblastoma should be considered for these tumors. It is thus recommended to perform genetic testing on diffuse gliomas with PLNTY features in order to facilitate integrated diagnosis and provide molecular evidence for accurate evaluation of prognoses.

Objective:To investigate the clinicopathological features, pathological classification, and molecular characteristics of pulmonary hamartomas.Methods:A retrospective analysis was conducted on 316 cases of pulmonary hamartomas diagnosed at Nanjing Chest Hospital, Nanjing, China from January 2015 to June 2024. Next generation sequencing (NGS) was performed on 15 cases of this study. The clinical data, histopathological features, immunophenotypes, and molecular alterations were analyzed. Relevant literature was reviewed.Results:Among the 316 patients, there were 154 males and 162 females, with an average age of 56±10 years. Among the 316 cases, 310 were intrapulmonary hamartomas and 6 were intraluminal bronchial hamartomas. Microscopically, there were complex proliferative mesenchymal components and epithelial components, presenting various combinations and hamartomatous morphologies. These hamartomas were morphologically classified into mesenchymal-type hamartomas (cartilaginous, fibrous, smooth muscle, adipose tissue, and mixed types) and epithelial-mesenchymal mixed-type hamartomas (respiratory epithelial-mesenchymal mixed and mucosal gland-mesenchymal mixed types). The cartilaginous hamartomas accounted for 72.8% (230/316) of them, and the non-cartilaginous hamartoma accounted for 27.2% (86/316). Secondary changes such as calcification, ossification, collagenization, mucin degeneration, and cystic changes were commonly present. The immunophenotype was CK7 +/TTF1 + for respiratory epithelial cells, or TTF1 -/CK7 +/p40 + for interstitial cells. Interstitial cells might express desmin, SMA, S-100, caldesmon, etc, while CD34 +/CD10 +/ER + spindle-shaped interstitial cells were also commonly noted. Genetic variations were detected in 11 of the 15 cases that were subject to NGS, including HMGA2-related fusion genes, EP300 mutations, FLT1 mutations, JAK1 mutations, SETD2 and TAP2 mutations, and high-copy amplification of CDK4/PHF1/TSPAN31. The patients were followed up for 6 to 110 months without any known recurrence or metastasis. Conclusions:Pulmonary hamartomas mainly occur in the peripheral lung parenchyma, with the cartilaginous type being the most common. Their clinical pathological and molecular features of pulmonary hamartomas are characterized and the histological types are roughly ascertained in this study, with emphasis of the key points of diagnosis and differential diagnosis. Classification of pulmonary hamartomas is valuable for guiding future research. Pulmonary hamartomas overall have a good prognosis. However, those with cystic changes or intraluminal hamartomas in the bronchus may cause serious airway lesions and therefore require special attention.

Objective:To investigate the clinical, cytopathological characteristics, and differential diagnosis of metastatic clear cell renal cell carcinomas (CCRCC).Methods:Nine cases of metastatic CCRCC cytologically diagnosed in the Department of Pathology, the First Affiliated Hospital of Air Force Medical University from July 2021 to December 2024 were collected. The HE staining, May-Grunewald-Giemsa staining, liquid-based slides, cell block preparation, and immunocytochemistry of EnVision two-step staining were performed. The clinical and cytopathological features, treatments and follow-up data were analyzed in combination with literature review.Results:Among the 9 cases of metastatic CCRCC, there were 7 males and 2 females. The age range was 43-78 years, and the average age was 63.6 (57.5, 72.5) years. The metastatic sites were lymph node in 3 cases (2 cases of mediastinal lymph nodes and 1 case of left cervical lymph node), bone in 3 cases (pubis, thoracic vertebrae and femur, respectively), thyroid in 2 cases, and adrenal gland, lung and pancreas in 1 case, respectively. Two of the 9 cases had two metastatic sites (case 8 had metastases of lung and mediastinal lymph nodes; case 9 had metastases of thyroid and cervical lymph nodes). The median time from the diagnosis to metastasis was 9.4 years (range 1.1 to 13.8 years). The tumor cells were arranged in papillary, acinar, sheet, cluster or single scattered pattern. Most cases had uniform nuclei with mild atypia and inconspicuous nucleoli, while some cases had variable nuclei with prominent nucleoli. The cytoplasm of the tumor cells was abundant. Some cases showed clear cytoplasm with small vacuoles, while some of them showed eosinophilic and granular cytoplasm. Immunocytochemically, the tumor cells were positive for CKpan(AE1/AE3,6/6), PAX8 (9/9), CAⅨ (9/9), CD10 (9/9), and vimiten (8/8). Patients were treated primarily with targeted therapy and/or immunotherapy and curettage and radiation therapy for bone lesions. The follow-up time ranged from 1.0 month to 41.5 months (median, 20 months), and all patients survived at the end of follow-up.Conclusions:The cytology of metastatic CCRCC often shows uniform cell size, abundant and clear cytoplasm, low nuclear/cytoplasmic ratio, and mild nuclear atypia. Its cytological diagnosis is challenging because it occurs in various sites and needs to be differentiated from primary tumors of these sites. Emphasis should be placed on the morphological recognition of CCRCC, and immunocytochemical staining should be used to improve diagnosis. When necessary, molecular testing can be employed for diagnosis. Meanwhile, the medical history should be carefully inquired by pathologists to avoid missed diagnosis and misdiagnosis.

Objective:To investigate clinicopathological and molecular genetic characteristics of CD117-positive eosinophilic renal cell tumors (ERCTs) with unusual morphological and immunophenotypic features.Methods:Formalin-fixed, paraffin-embedded tissues from 10 cases (9 cases from Xiangya Hospital, Central South University and 1 case from Bishan Hospital of Chongqing Medical University) of diagnostically challenging CD117-positive ERCTs between January 2017 and October 2024 were collected. Histological reviews were performed on HE-stained sections, followed by immunostaining and whole-exome sequencing (WES).Results:The 10 patients were composed of 4 males and 6 females, with ages ranging from 29 to 57 years, median 49.5 (36.8, 51.8) years. The sizes of tumors ranged from 2.5 to 6.0 cm, median 4.8(2.9,5.2) cm. All 10 ERCTs were composed of variably eosinophilic cells and characterized by prominent morphological features including exclusively eosinophilic (2 cases), focal chromophobe-like (3 cases), prominent nested (2 cases), prominent flocculent cytoplasm (1 case), a collision of renal oncocytoma (RO)/chromophobe renal cell carcinoma (ChRCC) (1 case), and diffusely degenerative atypia (1 case). Immunohistochemically, a subset of 10 tumors variably expressed CK7 (7/10) and vimentin (3/10), while they were all positive for CD117 (10/10), PAX8 (10/10), SDHB (10/10), and FH (10/10) and negative for CAⅨ (10/10) and 2SC (10/10). The Ki-67 proliferation index ranged from 1% to 5%. WES identified a GNAS mutation in one case of the RO/ChRCC collision tumor, while no characteristic mutations of other renal cell tumor types were detected in the remaining 9 cases. The analysis of copy number variations revealed complex karyotypic alterations in 4 tumors, harboring various gain of chromosomes 4, 5, 7, 12, 13, 15, 16, 18, and 22, with 3 cases showing variable loss of chromosomes 1, 2, 6, 10, 13, and 17. These 4 cases were molecularly classified as eosinophilic ChRCC. The remaining 6 cases, including 2 cases with a normal diploid karyotype and 4 cases with slight karyotypic alterations, were molecularly classified as 5 ROs and 1 RO-dominant RO/ChRCC collision tumor. Finally, the original diagnosis was retained in 4 cases and revised in 6 cases.Conclusions:CD117-positive ERCTs with uncertain classification may exhibit various morphological overlaps, non-classic histological features, and aberrant immunophenotypes. Combined immunostaining of CK7, CD117, vimentin, SDHB, FH, and 2SC can greatly help discriminate among these tumors and their mimics. When the diagnosis is challenging based only on morphology and immunohistochemistry, molecular genetic tests may be useful.

Objective:To assess the clinicopathological characteristics of non-muscle-invasive bladder cancers (NMIBC) with high expression of human epidermal growth factor receptor 2 (HER2) and to examine the prognostic values of HER2 expression in NMIBC patients with intravesical anthracycline instillation.Methods:A total of 221 NMIBC samples diagnosed between January 1, 2017 and April 15, 2024 were collected. Their clinical, diagnostic and treatment features were analyzed. The expression of HER2 protein and the Ki-67 proliferation index were assessed using immunohistochemistry (IHC). For the patients with HER2 high-expression (IHC 3+), the clinical pathological features (age, gender, tumor grade, Ki-67 expression level, tumor size, and tumor number) were compared with those without (i.e., HER2 IHC 0/1+/2+). The impact of HER2 expression on the recurrence-free survival (RFS) of patients with intravesical anthracycline (epirubicin or pirarubicin) instillation after transurethral resection of bladder tumor (TURBT) was evaluated.Results:Among the 221 NMIBC patients, 30 (13.6%) were HER2 IHC 3+, 142 (64.3%) HER 2+, 46 (20.8%) HER2 1+, and 3 (1.4%) HER2 IHC 0. The proportion of high-grade tumors in patients with HER2 high-expression was higher than that in patients without (83.3% versus 44.5%, P<0.001). Additionally, a high Ki-67 index (≥20%) was more commonly noted in HER2 high-expression tumors ( P=0.003). In the patients treated with intravesical anthracycline instillation, HER2 high-expression was associated with a shorter RFS ( P<0.001). Conclusion:HER2 high-expression seems to be not only associated with worse clinicopathological features of NMIBC but also a poor RFS in NMIBC patients treated with anthracycline instillation after TURBT.

Objective:To investigate the clinicopathological features, immunophenotype and prognosis of SWI/SNF complex-deficient sinonasal carcinomas.Methods:The clinicopathological, immunohistochemical profiles of 13 SWI/SNF complex-deficient sinonasal carcinomas diagnosed at Xuanwu Hospital, Beijing, China between Januay 2019 and December 2024 were reviewed and followed up.Results:The patients′ ages ranged from 33-81 years, median 59.0 (41.5, 64.5) years, including 10 males and 3 females. Imaging findings showed space-occupying lesions in the nasal cavity and sinuses. Microscopically, tumors predominantly exhibited invasive growth in medium-to-large nests or sheets, with relatively uniform morphology, mainly basaloid and/or small cells, while one recurrent case displayed epithelioid morphology. Focal necrosis was observed in 7 cases. Immunohistochemical results showed loss of SMARCA4/BRG1 in 7 cases, loss of SMARCB1/INI1 in 6 cases, and concurrent loss of SMARCA2 in 5 cases. CKpan was expressed to varying extent in all cases, 10 cases were EMA positive, and 5 cases were partially positive for p63/p40. Among neuroendocrine markers, 10 cases showed focal expression of syn or CgA. The Ki-67 proliferation index ranged from 40% to 90%. PD-L1 staining showed combined positive score (CPS) was ≥1 in 3 SMARCB1-deficient cases (CPS ranging from 2 to 3) and CPS <1 in the other 10 cases. Among the 13 patients, 2 were lost to follow-up, 6 died (postoperative survival: 1-25 months), and 5 remained alive, with the longest survival time of 130 months (follow-up range, 8-130 months).Conclusions:SWI/SNF complex-deficient sinonasal carcinoma is a rare undifferentiated malignancy in the head and neck, characterized by distinct pathological and molecular genetic features. SMARCA4-deficient and SMARCB1-deficient carcinomas both exhibit basaloid or small cell-like morphology. Compared to SMARCB1-deficient carcinomas, SMARCA4-deficient carcinomas show reduced expression of squamous cell markers but increased expression of neuroendocrine markers. The positive PD-L1 staining is more likely present in SMARCB1-deficient carcinomas than SMARCB4-dificient ones. Co-loss of SWI/SNF and SMARCA2 correlates with poorer prognosis. Comprehensive evaluation of histopathology, immunohistochemistry, and molecular genetics is critical for accurately diagnosing this rare entity.

Over the past decade, pathology technology in China has undergone rapid development. Through continuous efforts to strengthen normative foundations and quality control, the three-tiered quality control network (national, provincial, and municipal) has been consolidated. These efforts have effectively driven the homogenization of pathology technical quality nationwide. Concurrently, the standardization of laboratory quality management systems and the advancement of automated pathological equipment have laid a solid foundation for the evolution of pathological diagnosis. Breakthroughs in cutting-edge technologies, including digital pathology, artificial intelligence, and molecular pathology, are further catalyzing a paradigm shift from traditional morphological analysis toward next-generation diagnostic pathology. Marking the 70th anniversary of this journal, the field's evolution over the past decade and chart its future course were reviwed systematically, aiming to provide an insightful roadmap for the ongoing progress of the discipline.