Objective:To compare the results of plasma samples and histological/cytological samples for detection of lung cancer driver gene by next-generation sequencing (NGS), to provide reference for sampling selection of clinical patients.Methods:A retrospective analysis was performed on 220 patients with lung cancer who were admitted to Quanzhou First Hospital in Fujian Province from May 2017 to May 2024, and NGS detection of lung cancer driver gene was performed on both plasma samples and histological/cytological samples. Histological specimens included biopsy or surgical resection of lung cancer, cervical lymph nodes and pleural metastases; the cytological specimen was pleural fluid cell wax block. Specimens were divided into plasma group (experimental group) and matched histological and cytological group (control group). Eight gene variants recommended by the guidelines were EGFR mutation, ALK rearrangement, ROS1 rearrangement, BRAF V600 mutation, RET rearrangement, MET exon 14 jump mutation, KRAS mutation, and NTRK1/2/3 rearrangement. The detection results of the two groups of specimens were compared and analyzed.Results:Among the 220 cases, 183 were adenocarcinoma, 23 were squamous cell carcinoma and 14 were non-small cell lung cancer. There were 4 cases in stage Ⅰ, 3 cases in stage Ⅱ, 24 cases in stage Ⅲ, and 189 cases in stage Ⅳ. In the plasma group, 120 cases were positive, the detection rate was 54.5%; There were 152 positive cases in the control group, the detection rate was 69.1%; the detection rate in the plasma group was lower than that in the control group ( χ2=6.12, P<0.05). The detection rate of plasma in patients with stage Ⅰ/Ⅱ/Ⅲ was 12.9% (4/31), which was significantly lower than that in stage Ⅳ (61.4%; χ2=22.10, P<0.05). In the early clinical stage (stage Ⅰ/Ⅱ) of 7 cases, 3 cases were positive in the control group, while all were negative in the plasma group. There were 24 stage Ⅲ cases, 8 were positive in the control group and 4 were positive in the plasma group. Among the positive cases in the control group, 34 were negative and 4 were not detected in the matched plasma group. In the plasma positive cases, there were 2 negative cases and 4 partial mutations were not detected in the matched control group. Among these 6 cases, 5 were treated patients, and the mean mutation abundance of corresponding plasma positive genes was 1.5%. There were 110 cases with the same positive result (the same mutation site) and 66 cases with the same negative result, with agreement rate of 80.0% (176/220). The sensitivity and specificity of the plasma group were 75.0% (114/152) and 91.7% (110/120), respectively. Conclusions:When NGS is used for lung cancer driver gene detection, the positive rate of plasma samples is lower than that of tissue/cytology samples, but the consistency rate with the latter can reach 80%, and the sensitivity is higher than 70%, which has a good clinical detection efficiency, especially for patients with non-small cell lung cancer stage Ⅳ.

Objective:To investigate the variations and co-alteration of KRAS and HER-family genes in the patients with ampullary carcinoma.Methods:A total of 37 formalin-fixed paraffin-embedded primary ampullary carcinoma specimens, which were collected at Peking Union Medical College Hospital from April 2019 to October 2024 were analyzed for KRAS and HER-family gene mutations using next-generation sequencing (NGS). Immunohistochemistry (IHC) was performed for HER2 protein expression in HER2 mutation cases and fluorescence in situ hybridization (FISH) for further gene status in HER2 IHC 2+cases.Results:In our cohort (22 males, 15 females; 31-82 years old), KRAS gene mutations were detected in 51.4% (19/37) of cases, with G12D being the most frequent abnormality (7/19), followed by G12V (5/19) and Q61R (3/19). Other variants of KRAS gene included G12C, A146T, N116H, and Q61H (each 1/19). In this cohort, 27.0% (10/37) of cases harbored HER-family gene alterations with most frequently in HER2 (6/10) and HER3 genes (missense mutations mainly). Notably, 3 cases (8.1%, 3/37) with coexistence of KRAS and HER-family genes mutations were recognized in our series, including KRAS p.G12D/HER2 p.V842I/HER2 p.V777L (c.2329 G>T)/HER3 p.Asp581Asn, KRAS p.Q61R/HER4 p.D1018H and KRAS p.G12C/HER2 p.R678Q. Additionally, a mutation of HER3 p.V104L (c.310 G>C) was identified in our population. Moreover, 4 novel mutations including HER3 p.V296E, HER3 p.V920L (c.2758 G>T), HER3 p.Asp581Asn, and HER4 p.D1018H were detected. In 6 tumors with HER2 gene changes (16.2%, 6/37), 5 variants with the high proportion of HER2 p.S310Y (3/6) were revealed. A tumor (HER2 IHC 2+) with HER2 p.S310Y presented HER2 gene amplification confirmed by NGS and FISH, and another one (also HER2 IHC 2+) with HER2 p.L755S possessed HER2 gene amplification determined by FISH assay.Conclusion:In ampullary carcinoma, co-alteration of KRAS and HER-family genes is observed, and HER2 gene mutations account for more than half of HER-family gene abnormities, which may be accompanied by gene amplification.

Objective:To investigate the clinical manifestations, histological features, immunophenotype, molecular characteristics, and treatments of uterine inflammatory myofibroblastic tumor (UIMT).Methods:Clinical and pathological data of 4 UIMT cases diagnosed at the Peking Union Medical College Hospital, Beijing, China from 2020 to 2024 were collected. Their clinicopathological and genetic characteristics were analyzed.Results:The patients′ ages were 63, 42, 53 and 37 years, respectively. The tumors were located in the submucosa and intermuscular walls of the uterus, with a diameter ranging from 1.5 to 6.0 cm. All tumors were suspected by the clinician as leiomyosarcoma. Histologically, 3 of the 4 tumors showed spindle cells that appeared like leiomyoma. Prominent myxoid stroma and inflammatory cells infiltration were observed, with mitotic figures of 1-2 per 10 high-power fields. One case was primarily composed of spindle cells arranged in fascicles, with inflammatory cell infiltration, inconspicuous myxoid stroma and mitotic figures of 3 per 10 high-power fields. Two cases exhibited a pushing pattern of invasion and slightly unclear boundaries, while the other two showed infiltrative growth with unclear boundaries. The immunohistochemistry revealed diffuse and strong, cytoplasmic granular staining of ALK in all 4 cases. RNA sequencing was performed in 3 cases, of which 2 cases showed ALK gene rearrangements, and 1 case did not. One case underwent FISH testing and showed ALK gene translocation. Follow-up showed that no recurrence or metastasis was observed after surgery in all patients.Conclusions:UIMT is a rare mesenchymal tumor of the uterus and lacks specific clinical manifestations. When tumor cells exhibit mild atypia, indistinct borders, myxoid stroma, inflammatory cell infiltration, and decreased expression of ER and PR on immunohistochemistry, immunohistochemical staining of ALK is recommended to confirm the diagnosis of UIMT. This tumor shares many features with myogenic tumors and endometrial stromal sarcomas. Molecular testing may also be needed to assist in diagnosis when necessary. For patients who are not suitable for surgery or have recurrence and metastasis, targeted therapy with ALK inhibitors can be used.

Objective:To investigate the clinicopathological characteristics and molecular genetic alterations of cervical embryonal rhabdomyosarcoma (ERMS).Methods:Three cases of cervical ERMS diagnosed at Peking University Third Hospital from April 2017 to April 2023 were retrospectively analyzed. Clinicopathological data, molecular genetics, treatments, and follow-up information were examined.Results:Three patients with cervical ERMS, aged 17, 15, and 23 years, respectively, were included. All presented with polypoid masses at the vaginal opening. Histologically, oval or short-fusiform tumor cells in myxedematous stroma were arranged in dense and sparse regions, accompanied by various degrees of rhabdomyoblastic differentiation. Immunohistochemically, MyoD1, Myogenin and Myoglobin were expressed in all 3 tumors. The DICER1 gene mutation was detected in all 3 tumors, while the DICER1 germline mutation was detected only in 2 cases. All patients received local resection and adjuvant chemotherapies. The follow-up period was 10-76 months. One patient experienced local recurrence, and two remained disease-free.Conclusions:Cervical ERMS predominantly affects young females and commonly presents as a prolapsed polypoid cervical lesion. It demonstrates distinctive molecular genetic characteristics, most frequently DICER1 mutations, and shows a strong association with the DICER1 syndrome.

Extranodal NK/T-cell lymphoma (ENKTL) is an Epstein-Barr virus (EBV)-associated extranodal lymphoma derived from NK or T cells. It exhibits strong geographical and ethnic predispositions and is relatively prevalent in China, making it one of the common lymphoma types in our country. Most cases of this tumor exhibit aggressive biological behavior, and timely, accurate pathological diagnosis is crucial for improving cure rates and patient prognosis. However, the tumor has a broad histopathological spectrum, diverse morphological features, and lacks specific immunomarkers, which can lead to misdiagnosis or underdiagnosis in some cases. Additionally, it is necessary to integrate clinical, imaging, and laboratory findings to differentiate ENKTL from a range of EBV-positive lymphoproliferative disorders. In recent years, with the continuous advancement of molecular biology technologies, significant progress has been made in the molecular genetic research of ENKTL. This article aims to summarize the latest advances in the pathological research of ENKTL, emphasizing the diagnostic challenges, pitfalls, and strategies to avoid them, thereby enhancing pathologists′ understanding of this tumor and enabling precise diagnostic stratification.

Objective:To explore the clinicopathological and molecular genetic characteristics of anaplastic lymphoma kinase (ALK)-rearranged renal cell carcinoma (RCC), including a rare case with the TPM1-ALK gene subtype.Methods:Three cases of ALK-rearranged RCC diagnosed in the Department of Pathology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China from January 2020 to December 2024 were collected. Their clinical pathological and next-generation sequencing (NGS) data were analyzed. Relevant literature was also reviewed, and follow-ups were carried out.Results:Among the three patients, there were 1 female (case 1) and 2 males (cases 2 and 3), with the ages of 29,41 and 44 years, respectively. All of them were presented with space-occupying renal lesions. Case 1 (KIAA1217-ALK RCC) showed mixed cystic and solid components under the microscope, with tubular, papillary, and cribriform arrangements. The tumor cells had clear boundaries, and were cubic or low columnar, arranged in a single layer, pseudostratified or in sheets. The cytoplasm was abundant and eosinophilic, and part of the cytoplasm was vacuolated, as if there was accumulation of mucoid substances. The tumor cell nuclei were oval with prominent nucleoli. A large amount of mucus and inflammatory cell infiltration were noted in the stroma. Case 2 (TPM1-ALK RCC) showed a papillary growth pattern, with small, slender papillae accompanied by branches. The cells were arranged in a single layer, and the cytoplasm was either eosinophilic or clear. Foamy cells were aggregated in the stroma, accompanied by psammoma body-like calcifications. Case 3 (EML4-ALK RCC) was characterized by papillary and tubulocystic structures. The cytoplasm was abundant and eosinophilic. The tumor cell nuclei were large, with prominent nucleoli. There was conspicuous infiltration of lymphocytes and neutrophils in the fibromuscular stroma. The tumor cells all expressed epithelial markers, PAX8, GATA3, P504s and FH. ALK (5A4) staining showed diffuse strong expression in the cytoplasm, while TFE-3 was positive (nuclear stain) only in case 1 and case 3. The fluorescence in situ hybridization showed that ALK gene rearrangement was present in all three cases, while TFE-3 gene rearrangement/mutation was not detectable in case 1 and case 3. NGS showed the KIAA1217::ALK fusion (the fusion site in the exon 11 of KIAA1217 and exon 18 of ALK) in case 1, the TPM1::ALK fusion (the exon 8 of TPM1 and exon 20 of ALK) in case 2, and the EML4::ALK fusion (the exon 2 region of EML4 and the exon 20 region of ALK) in case 3.Conclusions:ALK-rearranged RCC has unique molecular characteristics. Its histological morphology is easily confused with that of papillary RCC and TFE3-rearranged RCC. Both immunohistochemistry and gene rearrangement tests should be used to confirm the diagnosis.

Objective:To investigate the clinicopathological characteristics of well-differentiated papillary mesothelial tumor (WDPMT).Methods:Sixteen cases of resected WDPMTs diagnosed at the Affiliated Hospital of Qingdao University, Qingdao, China from 2017 to 2024 were collected and the clinicopathological features were retrospectively analyzed.Results:There were 7 males amd 9 females, with a mean age of 53.8±14.8 years (range, 25-83 years). Tumor size ranged from 3 to 12 mm in maximum diameter. Of the 16 cases, 15 involved the peritoneum and 1 involved the pleura, one of which occurred on the surface of ovary. All cases were incidentally identified during unrelated surgical procedures. Histologically, tumors exhibited arborizing papillary growth patterns and frequently displayed hierarchically branching papilla. Tumor cells showed cuboidal to flattened cell morphology with minimal nuclear atypia. Mitotic figures were not noted in all cases. Entrapped gland-like tumor cell clusters were found in the stroma of tumor papilla in 1 of the 16 cases. Immunohistochemically, the tumor cells expressed mesothelial markers (Calretinin, D2-40, and CK5/6) in all cases, and BAP1 and MTAP were immunoreactive in all tested cases. Fluorescence in situ hybridization revealed no CDKN2A deletions.Conclusions:WDPMT predominantly occurs in the peritoneum and typically demonstrates indolent biological behaviors. It often shows overlapping features with mesothelioma in situ and epithelioid mesothelioma. The hierarchical branching papillae is its diagnostic hallmark, while routine immunohistochemical evaluation of BAP1 and MTAP is also recommended for differential diagnosis of these tumors.

Objective:To investigate the clinicopathological features of SMARCA4-deficient uterine sarcoma.Methods:Five cases of SMARCA4-deficient uterine sarcoma at the Department of Pathology, the First Affiliated Hospital of Nanjing Medical University from 2018 to 2024 were collected. The morphological and immunohistochemical features were observed and analyzed. A follow-up study was also carried out.Results:Five female patients, aged 24, 54, 56, 61, and 41 years, respectively, presented with vaginal bleeding or abdominal pain. All patients had imaging findings of intracavitary lesion in the uterus, with tumor sizes ranging from 3.0 cm to 8.8 cm. The patients were followed up for 2 to 14 months. Case 1 died 9 months after surgery, whereas the remaining four patients were still alive. Histologically, the tumor cells exhibited a diffuse growth pattern, with an infiltration depth involving more than half of the myometrium. Portions of the interstitium appeared sclerosed. Benign endometrial glandular structures were observed in a leaf-like or fissured pattern, resembling those of uterine adenosarcoma. The tumor cells were large epithelioid with abundant or faintly eosinophilic cytoplasm, and the nuclei were moderately to markedly atypia with prominent nucleoli and brisk mitosis. Rhabdoid cells were seen. Some areas showed small round blue cells, with occasional spindle cells and myxoid stroma. Additionally, widespread or focal lymphovascular space invasion was observed within the myometrium. All five cases exhibited absence of SMARCA4 (BRG1) expression and retained SMARCB1 (INI1). Claudin4 expression was negative. There was no deficient expression of mismatch repair proteins MLH1, PMS2, MSH2 and MSH6. p53 showed wild-type expression. Ki-67 index ranged from 30% to 60%. CKpan, CK7, ER, PR, and PAX8 were negative.Conclusions:SMARCA4-deficient uterine sarcoma is rare, highly aggressive, and has a poor prognosis. The tumor exhibits a broad morphological spectrum, with rhabdoid cells and adenosarcoma-like structures serving as important diagnostic clues. The absence of BRG1 expression lends support to a definitive diagnosis.

Medullary thyroid carcinoma (MTC) is the most common neuroendocrine carcinoma within the thyroid gland, characterized by strong invasiveness, high metastasis and recurrence rates. It is relatively rare among thyroid malignancies. The cytological and histological features of MTC are diverse and disperse, presenting as papillary, follicular, solid, trabecular, and spindle cell patterns. Immunohistochemical staining shows variable expression of calcitonin, carcinoembryonic antigen, and neuroendocrine markers. MTC can be classified into hereditary and sporadic types, with most cases caused by germline or somatic mutations in the RET gene located on chromosome 10. The 5th edition World Health Organization classification of endocrine and neuroendocrine tumors categorizes MTC into low-grade and high-grade based on tumor necrosis, mitotic figures, and Ki-67 proliferation index, highlighting that histological grading and RET gene mutations are independent prognostic predictors. This paper summarizes the recent advances in the pathological diagnosis of MTC, focusing on the key roles of the MTC grading system, molecular characteristics, and genetic screening and counseling in risk stratification for recurrence and targeted therapy.

With the development of precision medicine and molecular pathology, fluorescence in situ hybridization (FISH) technology has been widely promoted and applied in department of pathology. In FISH detection, the most commonly used probes are HER2 amplification probes and a variety of separation probes. When detecting pathological specimens using separation probes, some specimens may show atypical signals other than the typical red-green separation signals. The observation, understanding and interpretation of atypical signals may affect the results of FISH, which are related to molecular subtyping and drug treatment of the patient. Eight types of atypical signals of separation probes in FISH detection based on reading experience were summarized and analyzed. At the same time, this article provides evidence and analysis on whether the gene has been rearrangedthrough verification experiments, image analysis and experimental analysis in literature, aiming to enhance the understanding of readers to atypical signals of FISH separation probes.