Mesonephric-like adenocarcinoma (MLA) in the corpus uteri is a highly aggressive malignant tumor, which is easily confused with other types of endometrial cancer. When the tumor morphology and cellular characteristics are not consistent with the clinical biological behavior, attention should be paid to it. This study is to investigate the clinicopathologic features of MLA in the corpus uteri. Three cases of MLA in the corpus uteri diagnosed in the First Affiliated Hospital of Xi'an Jiaotong University from 2020 to 2023 were studied by clinical data, microscopic features and immunohistochemistry. The related literature was reviewed. The clinical manifestations of the three cases of MLA in the corpus uteri were nonspecific. One case was from our hospital and the other two cases were from other hospitals. The age range was 54-58 years. In the specimen description, there was a diffusely growing mass in the endometrium of the uterus, with an uneven surface and tough texture. The muscle wall was extensively invaded. At low magnification, the tumor cells were arranged in tubular, glandular, papillary, micropapillary and solid growth patterns. At high magnification, the cells lining the lumen were arranged in a single layer, cuboidal or columnar pattern, with mild to moderate atypia, with vesicular nuclei and nuclear furrows. Some of the lumens showed eosinophilic homogeneous pink staining without structural-like material. In the solid area, the cells were plat fusiform, arranged in bundles or whirlpools, with large nuclear atypia and frequent mitotic figures. A large number of intravascular cancer thrombus were observed in all the three cases. The tumor cells were positive for GATA3 and/or thyroid transcription factor-1 (TTF1), diffusely positive for pair box gene 2 (PAX2) and PAX8, and positive for CD10 in some luminal margins. Estrogen receptor (ER) was focal positive, and progesterone receptor (PR) was negative. KRAS mutation was detected in case 1. According to the 2023 updated International Federation of Gynecology and Obstetrics (FIGO) staging guidelines for endometrial cancer, all the three cases were in advanced stage. It is suggested that pathologists should make accurate diagnosis based on morphological manifestations, using a set of matched immunohistochemical markers and necessary molecular tests to avoid misdiagnosis and better guide clinical diagnosis and treatment.

To explore the effects and the molecular mechanisms of homo sapiens longevity assurance homolog 2 of yeast LAG1(LASS2) dephosphorylation on the biological functions of prostate cancer cells.

Objective: To investigate the response to induction chemotherapy (IC) as prognostic indicators for radiotherapy response and survival outcomes in patients with loco-regionally advanced tonsil squamous cell carcinoma (LATSCC). Methods: A retrospective analysis was conducted on 84 LATSCC patients who were admitted to the Eye & ENT Hospital of Fudan University. There were 67 males and 17 females, aged from 42 to 76 years. Among them, 55 patients (65.5%) were p16 positive and 29 patients (34.5%) were p16 negative. All patients received initial IC with TPF chemotherapy regimen (docetaxel+cisplatin+capecitabine) followed by either radiotherapy alone or concurrent chemoradiotherapy. The differences in categorical variables were compared using Chi-square test and Fisher exact test. Logistic regression was employed to identify independent factors associated with radiotherapy sensitivity. Kaplan-Meier method was utilized to calculate cumulative survival, while Log-rank test and Cox risk model were performed for univariate and multivariate analyses of overall survival (OS), locoregional relapse-free survival (LRFS), and distant metastasis free survival (DMFS). Results: After IC, the objective response rates (ORR) in p16 positive group and p16 negative group were 87.3% and 89.7%, respectively (χ2=0.103, P=0.749). Following radiotherapy, the complete response rates in p16 positive group and p16 negative group were 87.3% and 72.4%, respectively (χ2=5.058, P=0.115). Sensitivity to IC (OR=10.883, 95%CI: 2.555-45.930, P=0.001) was independently associated with complete response to radiotherapy and in the p16 positive group, the 3-year OS, LRFS, and DMFS were 90.0%, 81.5%, and 96.4%, respectively. In the p16 negative group, they were 82.1%, 89.1%, and 92.0%, with no statistically significant difference in the rates between two groups(P>0.05). Compared to IC-resistant patients, IC-sensitive patients showed significant improvements in 3-year LRFS (90.2% vs. 40.0%, χ2=19.750, P<0.001). IC resistance was identified as an independent risk factor for LRFS (HR=2.180, 95%CI=1.235-3.849, P=0.007). Conclusions: The response to IC is a significant prognostic factor for tonsil squamous cell carcinoma treated with definitive radiotherapy. Poor response to IC is associated with unsatisfactory outcomes either in p16-positive or p16-negative cancer.

Objective: To investigate the clinical characteristics of patients with oropharyngeal squamous cell carcinoma (OPSCC) and the relationship between the clinical characteristics and pre-treatment inflammatory parameters such as neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic inflammation response index (SII), and systemic inflammation response index (SIRI). Methods: A retrospective analysis was conducted on the clinical data of 149 OPSCC patients treated in two tertiary hospitals, Shanxi Province Cancer Hospital and Shanxi Bethune Hospital, between January 2017 and January 2024, including 129 males and 20 females, aged from 37 to 84 years old. The patients were grouped based on HPV infection status (p16 expression), namely p16-positive group and p16-negative group, and statistical analysis was performed to evaluate the correlation between the inflammatory parameters and clinical factors such as clinical stage, treatment regimen, and prognosis in two groups. Statistical analysis was conducted using SPSS 29.0 software. Results: In this cohort, 56.4%(84/149) of OPSCC patients were p16-positive. The total 1-year and 3-year survival rates were 87.0% and 66.5%, respectively. Analysis showed p16 status was an independent prognostic factor (HR=0.444, 95%CI: 0.206-0.957, P=0.038). No significant difference in prognosis was observed between p16-positive and p16-negative groups when NLR, PLR, and SII levels were elevated (all P>0.05). Pre-treatment SII levels were significantly higher in p16-positive patients compared to p16-negative patients (62.4% vs. 37.6%, χ2=8.021, P=0.005). Elevated pre-treatment PLR levels indicated a higher risk of lymph node metastasis (χ2=4.791, P=0.029). Conclusion: Elevated levels of NLR, PLR, and SII may attenuate the prognostic advantage of HPV-positive OPSCC. SII and PLR may play important roles in predicting HPV infection status and the risk of cervical lymph node metastasis in OPSCC patients.

Mantle cell lymphoma (MCL) is a subtype of B-cell non-Hodgkin lymphoma, typically diagnosed at an advanced stage with frequent extranodal involvement. Common sites of infiltration include the gastrointestinal tract, eye, liver, spleen, bone marrow, and central nervous system; however, pulmonary involvement-particularly tracheobronchial manifestation-is exceedingly rare. We report the case of a 60-year-old woman presenting with a 4-month history of cough and progressive dyspnea. Chest CT revealed a polypoid mass arising from the left tracheal wall, causing significant luminal narrowing. Under general anesthesia, bronchoscopic biopsy and tumor resection were performed, with histopathological examination confirming MCL.

Objective: To investigate the impact of the size of the liver tumor diameter on the prognosis of patients with hepatitis B-related hepatocellular carcinoma (HCC)-inducing acute-on-chronic liver failure (HBV-HCC/ACLF). Method: A retrospective cohort study was conducted. Clinical data of patients with hepatitis B-related acute-on-chronic liver failure (HBV-ACLF) diagnosed according to the Asia-Pacific Association for the Study of the Liver (APASLT) guidelines who were admitted to the Fifth Medical Center of PLA General Hospital between January 2016 and January 2021 were collected. The patients were enrolled in the HBV-HCC/ACLF group (116 cases) and the HBV-ACLF group (348 cases). General information, medical history, biochemical parameters, complications, and liver cancer status were collected. Clinical data and prognoses at 28 days and 12 months of follow-up were compared between the two groups. Factors influencing mortality in the HBV-HCC/ACLF group were analyzed to determine the prognostic significance of tumor diameter. The t test, χ2 test, and multivariate logistic regression analysis were used to analyze factors influencing mortality. Receiver operating characteristic (ROC) curves were used to assess the sensitivity and specificity of tumor diameter for 28-day prognosis, and Kaplan-Meier curves were used for survival analysis. Result: There were statistically significant differences in the 28-day mortality rate [(55.17%, 64/116) vs. (38.51%, 134/348)] and 12-month mortality rate [(78.45%, 91/116) vs. (55.75%, 194/348)] between the HBV-HCC/ACLF group and the HBV-ACLF group (P<0.05). The area under the ROC curve analysis for HBV-HCC/ACLF patients indicated that the tumor diameter was 0.707 (95%CI: 0.615-0.788). The survival group (52 cases) and the mortality group (64 cases) were divided into the HBV-HCC/ACLF group based on 28-day mortality. Univariate analysis showed that the levels of aspartate aminotransferase (AST), alkaline phosphatase, creatinine, alpha-fetoprotein, white blood cell count, international normalized ratio, model for end-stage liver disease score, acute kidney injury (AKI), the occurrence of infections and complications, and others were all significantly higher in the mortality group compared to the survival group (P<0.05).The mortality group had a larger tumor diameter than the survival group (P<0.01). The incidence of portal vein tumor thrombosis and distant liver cancer metastasis was also higher in the survival group (P<0.01). The mortality group had a higher rate of HCC-related minimally invasive treatment within three months before ACLF diagnosis than the survival group (P<0.01). AST levels, infection, size of tumor diameter, and minimally invasive treatment within three months before onset were independent risk factors for 28-day mortality in the HBV-HCC/ACLF group. The optimal significant value for tumor diameter affecting prognosis was 3.3 cm, with a sensitivity of 67.19% and a specificity of 73.08%. Patients with liver tumor diameters >3.3 cm had significantly lower 28-day survival rates than those with a tumor diameter ≤3.3 cm [(24.56%, 14/57) vs. (64.41%, 38/59)]. Eighty case analyses had the same findings in patients who had not previously received any therapy. Conclusion: Patients with HBV-HCC/ACLF had a high 28-day mortality rate, and the size of the tumor diameter is important in determining the 28-day prognosis.

Objective: To explore the effects of quercetin on autophagy and proliferation in HBV-positive liver cancer HCCLM3 cells based on STING signaling and its underlying mechanism. Methods: HCCLM3 cells were treated with quercetin (50 μmol/L or 100 μmol/L), designated as the 50 μmol/L group and 100 μmol/L group, respectively. The inhibitory effect of quercetin on HCCLM3 cells was detected using the CCK-8 method. A scratch assay was conducted to assess the impact of quercetin on the migration ability of HCCLM3 cells. A CCK8 and ROS kit was used to detect the effect of quercetin on the levels of reactive oxygen species in HCCLM3 cells. Western blotting was employed to measure the effect of quercetin on the expression of STING signaling and autophagy-related proteins in HCCLM3 cells. RNA interference technology was used to assess the effects of STING signaling inhibition on the expression of autophagy-related proteins and reactive oxygen species levels in HCCLM3 cells. The combined effects of STING activators and quercetin on HCCLM3 cell proliferation and autophagy were evaluated. The t-test was used to detect data differences between two groups, while ANOVA was employed for comparisons among multiple groups, followed by the SNK-q test for further pairwise comparisons. Results: Compared with the control group, quercetin (50 μmol/L and 100 μmol/L groups) significantly inhibited HCCLM3 cell survival activity in a dose-dependent manner (control group: 100%; 50 μmol/L group: 75.25%; 100 μmol/L group: 50.36%, P<0.01 ). Quercetin inhibited HCCLM3 cell migration in a dose-dependent manner (>2 h, control group: 187.16 μm; 50 μmol/L group: 145.22 μm; 100 μmol/L group: 88.21 μm, P<0.01), which significantly increased intracellular reactive oxygen species (ROS) levels in HCCLM3 cells (control group: 1.00; 50 μmol/L group: 1.565; 100 μmol/L group: 2.175, P<0.01). The phosphorylation level of STING was significantly increased (P<0.01), and the expression of autophagy-related protein microtubule-related protein 1A/1B light chain 3 (LC3) protein was significantly promoted (P<0.01). Compared with the quercetin group, the cell viability of the small interfering-STING+quercetin group was increased (quercetin group: 56.3%; small interfering-STING+quercetin group: 85.7%, P<0.05), while the expression of autophagy-related protein LC3 was decreased. Compared with the quercetin group, the cell viability of the quercetin+STING activator group was further decreased (quercetin group: 56.7%; quercetin+STING activator group: 35.4%, P<0.01), and the expression levels of STING and autophagy protein LC3 were significantly increased (P<0.05). Conclusions: STING signaling-regulated cell autophagy mediates the inhibitory effect of quercetin on the proliferation of HCCLM3 cells, and this effect is enhanced after administration of the STING agonist.

Objective: To investigate the clinical values of fluorescent PCR-capillary electrophoresis (PCR/CE) for detecting somatic mutations in the proofreading exonuclease domain of DNA polymerase epsilon (POLE-exo*) in endometrial carcinomas (EC), as compared with Sanger sequencing. Methods: A total of 280 EC cases diagnosed at the Department of Pathology at Peking University Third Hospital, Beijing, China from December 2022 to December 2023 were collected. Ten cases, which had previously been confirmed to harbor POLE pathogenic mutations through next-generation sequencing (NGS), were excluded. Subsequently, parallel sequencing using both PCR/CE and Sanger sequencing methods was conducted on the remaining 270 EC samples without prior POLE testing, aiming to examine 11 known pathogenic mutation-sites located within exons 9, 11, 13, and 14 of the POLE gene. NGS was then carried out on the EC cases in which the PCR/CE and/or Sanger sequencing results indicated the presence of POLE-exo*. Results: Among the 270 EC samples, POLE-exo* was detected in 4 cases (4/270, 1.5%) using Sanger sequencing. In contrast, the PCR/CE identified POLE-exo* in 12 cases (12/270, 4.4%). It was noteworthy that all cases in which POLE-exo* was detected through Sanger sequencing were also successfully identified using PCR/CE (4/4, with a detection rate of 100%). These results were further verified by NGS. The PCR/CE also uncovered an additional 8 cases (8/266, 3.0%) of POLE-exo* in the 266 samples that were negative for POLE mutations per Sanger sequencing. Of these 8 cases, 4 were validated using NGS, exhibiting variant allele frequency (VAF) below 10%, but tumor mutation burdens exceeding 10 mutations per megabase. However, due to small tumor sizes, NGS verification could not be performed on the remaining 4 PCR/CE-positive but Sanger-negative cases. Conclusion: The PCR/CE exhibits better sensitivity and detection capabilities than the Sanger sequencing in identifying POLE-exo* in EC samples, particularly in detecting low VAF.

Objective: To investigate the clinicopathological characteristics of ossifying fibromyxoid tumor (OFMT) with rare fusion subtypes. Methods: Three cases of OFMT with rare fusion subtypes, diagnosed and consulted in the Zhejiang Hospital, Zhejiang Provincial People's Hospital, Hangzhou, China and Ningbo Clinical Pathology Diagnosis Center, Ningbo, China from January 2016 to December 2024 were collected. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), and targeted RNA sequencing were performed to analyze the immunohistochemical and molecular genetic characteristics of these OFMT. Literature review was also conducted. Results: All three patients were male, with ages of 50, 74, and 58 years, respectively. The tumors were located in the left foot, left thigh, and left lumbar region, respectively, and all presented as slowly growing, painless masses in the skin or subcutaneous tissue. Grossly, the tumors measured 3.5 cm, 6.3 cm, and 5.0 cm in maximum diameter, respectively, with a grayish-white to grayish-yellow, solid, lobulated cut surface. One case exhibited a noticeable myxoid texture. Microscopically, one tumor was located in the superficial dermis, while the other two were in the subcutaneous tissue. The tumors were well-demarcated and showed a lobulated or multinodular growth pattern. None of the cases had a complete surrounding bony shell (only one case had very focal ossification). The tumor cells were monomorphic, short spindle-shaped, oval to epithelioid, and arranged in solid sheets, trabeculae, and small nests within a variably fibromyxoid stroma. Case 1 exhibited abundant pseudorosette-like structures formed by short spindle cells surrounding acellular fibrous stroma. Case 2 showed focal transition of epithelioid tumor cells into fasciculately arranged spindle cells, with extensive stromal hyalinization. Case 3 had a predominantly myxoid stroma with a rich network of thin-walled blood vessels. The tumor cells exhibited mild nuclear atypia with 1-3 mitotic figures per 50 high-power fields. All three cases showed diffuse and strong expression of CD10. Two of the three cases showed nuclear expression of TFE3, while one case showed diffuse and strong expression of desmin and S-100. Targeted RNA sequencing revealed PHF1 (ex12)::TFE3 (ex7) fusion in two cases and MEAF6 (ex5)::PHF1 (5'UTR) fusion in one case, which were further confirmed by FISH study. All three patients underwent tumor resection. Two showed no recurrence during follow-up periods of 98 months and 15 months, respectively, while one experienced local recurrence at 12 months postoperatively. Conclusions: OFMT with rare fusion subtypes often exhibits atypical histological and immunophenotypic features, and lacks a characteristic bony shell. Incorporating TFE3 into the diagnostic IHC panel greatly aids in screening for the cases with rare PHF1::TFE3 fusions. Familiarity with the histological and immunophenotypic characteristics, and differential diagnostic points of these rare OFMT subtypes, is essential for judicious use of molecular genetic tools in achieving a definitive diagnosis.

Objective: To investigate the clinicopathological characteristics, immunophenotype and differential diagnosis of atypical forms of microglandular hyperplasia of the cervix (AMGH). Methods: A total of 29 cases of AMGH diagnosed at the Obstetrics and Gynecology Hospital of Fudan University, Shanghai, China from January 2010 to December 2024 were analyzed. Relevant clinical and pathological data of the patients were collected using the electronic medical record system and medical records copied from the outside hospitals. The patients were followed up. Results: Among the 29 cases, 28 were consultation cases, 22 (79%) of the 28 cases were considered as glandular neoplastic lesions by the original institutions. The nature of the lesion was uncertain in 1 case, the diagnosis was suspicious for AMGH in another 1 case, and only 4 cases were clearly diagnosed as AMGH. The median age of the 29 patients was 44 (43, 48) years. Eighteen (62%) of the 29 cases presented as cervical polyp. Twelve of the 16 tested cases were negative for human papillomavirus. The pathological presentation was complex and diverse, including solid, trabecular, cribriform, and papillary patterns, forming pseudo-invasive structures. The glandular epithelium and proliferating reserve cells had diverse morphologies, which presented with abundant eosinophilic cytoplasm or clear cytoplasm. Signet-ring or hobnail cells were also seen. The nuclear atypia was mild, with 0-7 mitotic figures per 10 HPF. Immature squamous metaplasia was noted. The stroma showed edema, myxoid change and hyaline degeneration, accompanied by infiltration of acute and chronic inflammatory cells. Immunohistochemistry demonstrated that p16 was negative in 8/16 of the cases or patchy positive in the other 8/16, Ki-67 positive rate was less than 10% in all 16 cases, p53 was wild phenotype (9/9), and carcinoembryonic antigen was negative in 4/5 cases and focally positive in 1/5 cases, while p63 was positive in 6/9 of the tested cases. Conclusions: AMGH is a benign non-neoplastic lesion of the cervical glands. Half of the cases occur in perimenopausal or postmenopausal women, often presenting as polypoid hyperplasia or localized cervical thickening/elevation with a friable, fragile texture. Microscopically, it may show a pseudoinvasive pattern, making it prone to misdiagnosis as a malignant lesion. Thus, differentiation from cervical adenocarcinoma, clear cell carcinoma and microglandular endometrioid carcinoma is required. Integration of clinical history, immunohistochemistry and molecular testing may aid in the differential diagnosis.

Objective: To investigate the clinicopathological and molecular genetic characteristics of pediatric tumors with DICER1 mutations. Methods: A total of 90 patients diagnosed with various types of pediatric tumors at Beijing Children's Hospital, Capital Medical University, Beijing, China from July 2023 to September 2025 were included in this study. PCR amplification and Sanger sequencing were performed to detect the coding-region mutations of the DICER1 gene. The clinical, histopathological, and molecular genetic features of the cases with DICER1 mutation were then analyzed. Results: Among the 90 patients, 39 were male and 51 were female, with an age of onset ranging from 1 month to 17 years [median 7.13 (2.77, 10.37) years]. DICER1 mutations were detected in 37 patients (37/90, 41.1%). Among them, 9 cases harbored one mutation [6 pleuropulmonary blastomas (PPBs), 2 sex cord stromal tumors (SCSTs), and 1 cystic nephroma (CN)], 27 cases carried two mutations [10 PPBs, 3 anaplastic sarcomas of the kidney (ASKs), 3 SCSTs, 3 thyroid adenoma, 2 nodular thyroid goiters, 2 thyroid follicular lesions, 2 CN, 1 embryonal rhabdomyosarcoma, and 1 case with multiple primary tumors], and 1 case exhibited three mutations (bilateral ASKs). Despite variations in the site of origin, DICER1-mutant tumors shared several morphological features. Grossly, they presented as multilocular cystic, cystic-solid to solid masses. Microscopically, they exhibited a subepithelial layer of mesenchymal cells, with focal rhabdomyoblastic/chondroid/chondrosarcomatous differentiation, as well as cellular anaplasia. Germline testing using peripheral blood in the 31 patients with DICER1 mutation confirmed germline origin in 61.3% (19/31) of them. Parental analysis (n=12) demonstrated genetic inheritance in 8 cases, predominantly from families with tumor history. Germline variants scattered throughout DICER1 and consisted of loss-of-function mutations (nonsense, frameshift, and splice-site). Somatic mutations showed distinct clustering in exons 24 and 25 hotspots (codons 1705, 1709, 1809, 1810 and 1813), primarily missense variants. Notably, one multiple primary tumor case harbored a somatic mosaic p.E1705K mutation. Conclusions: DICER1 mutations are frequently detected in pediatric PPB, CN, SCST, ASK, nodular thyroid goiter, thyroid adenoma, and genitourinary rhabdomyosarcoma, which often represent as the index case of DICER1 syndrome. Performing DICER1 mutation testing in these patients not only facilitates tumor diagnosis and secondary cancer surveillance, but also enables the comprehensive genetic risk assessment and management for patient's family members.

Objective: To detect the expression of sialylated CD15 (CD15s) in the tumor cells of classical Hodgkin lymphoma using a modified immunohistochemical approach. Methods: From 2009 to 2024, 53 cases of classical Hodgkin lymphoma were collected in the Department of Pathology, Peking University Cancer Hospital, in which 21 cases that were CD15-negative or showed only focal weak positivity were selected. Immunohistochemical staining for CD15 was performed on a Leica automated stainer using three different antibody clones (MMA, Carb3, and IHC527). Tissue sections were digested with sialidase at varying concentrations and incubation times, followed by immunohistochemical staining with the MMA clone. Multiplex immunofluorescence was applied for co-staining of CD15 (MMA) and CD30 (JCM182), and analysis was conducted using APTIME and HALO software. Results: There were 30 male patients and 23 female patients, with an age range of 14 to 73 years and a median age of 32(26,46) years. None of the three CD15 antibody clones significantly improved the CD15 positive rate in the 14 completely negative and 7 weakly positive cases, with no notable differences observed among the clones(P>0.05). After sialidase digestion, tissue morphology remained well-preserved. Optimal CD15 staining was achieved with a 1∶1 diluted sialidase incubated at 37 ℃ for one hour. This treatment significantly enhanced the detection rate of CD15 antigen in Hodgkin Reed-Sternberg cells (P<0.001). Conclusion: Sialidase digestion effectively unveils sialylated CD15 expression in classical Hodgkin lymphoma, markedly improving its detection in HRS cells.

Objective: To investigate the clinicopathological features, diagnosis, and prognosis of renal solitary fibrous tumor (SFT). Methods: Five cases of renal SFT with unequivocal diagnoses at the Affiliated Hospital of Qingdao University between January 2011 and July 2025 were subject to analyses of their clinical, morphological, immunophenotypic, and molecular characteristics, accompanied by a literature review. Results: Two males and three females aged between 45 and 62 years were included, all of whom presented with the discovery of a renal mass during routine physical examinations. Gross examination showed that the five tumors were all confined in the kidney. The tumors were nodular with maximum diameters ranging from 2.5 cm to 11.0 cm (mean, 5.8 cm). Upon cross-sectioning, they exhibited gray-white or gray-yellow cut surface. Histologically, the tumor cells exhibited oval or short spindle shapes in four cases, presenting with varying densities and arranged in short bundles, woven patterns, and irregular formation. Various amounts of coarse collagen and scattered staghorn blood-vessels were found in the stroma. In one case (case 5), the tumor cells were long spindle-shaped, densely organized in bundles, and interwoven, exhibiting inconspicuous boundaries, moderate nuclear atypia, and at least 4 mitotic figures per 10 high-power fields. Irregular patchy collagen deposition was particularly prominent at the edges of the tumor tissue. In two cases (cases 3 and 5), scattered and various amounts of renal tubules were observed in the tumor. Two cases (cases 4 and 5) demonstrated focal invasion of the renal parenchyma, although no necrosis was noted. Immunohistochemical staining showed that the tumor cells were diffusely and strongly positive for vimentin and STAT6 in all 5 cases, and positive for CD34. Bcl-2 positivity was present in 4 of the 5 cases. All cases were negative for CKpan, EMA, PAX8, HMB45, Melan A, SMA, and S-100 protein. The p53 status was wild type, and the Ki-67 index ranged from 1% to 8%. Next-generation sequencing was conducted on one case (case 4), revealing the NAB2 (exon 3)::STAT6 (exon 18) gene fusion. The 5 patients were followed up for 1 to 158 months (mean, 56 months), and all were alive with no recurrence or metastasis. Conclusions: SFT of the kidney are rare and morphologically similar to extrarenal SFT. Key morphological features include short spindle-shaped tumor cells arranged in bundles, interwoven patterns or irregularly, accompanied by staghorn blood-vessels and scattered coarse hyaline collagen fibers. SFT with epithelial inclusions may represent a relatively common histological subtype in the kidney. Immunohistochemical staining that demonstrates diffuse and strong positivity for STAT6 and CD34 is instrumental in diagnosing this tumor. The pathogenesis is linked to the centromeric inversion of chromosome 12q, resulting in the fusion of the NAB2 and STAT6 genes. Most of these tumors exhibit favorable prognosis.