Primary central nervous system(CNS)tumors mainly include gliomas,meningiomas,etc,which have a relatively high incidence and mortality rate.In the 2021 WHO classification of CNS tumors,CDKN2A was included in the grading diagnostic criteria.p16/CDKN2A plays an important role in the diagnosis and treatment of CNS tumors.This article reviews the structural characteristics and mechanism of action of p16/CDKN2A,as well as the research progress in meningiomas and gliomas.

Primary central nervous system(CNS)tumors mainly include gliomas,meningiomas,etc,which have a relatively high incidence and mortality rate.In the 2021 WHO classification of CNS tumors,CDKN2A was included in the grading diagnostic criteria.p16/CDKN2A plays an important role in the diagnosis and treatment of CNS tumors.This article reviews the structural characteristics and mechanism of action of p16/CDKN2A,as well as the research progress in meningiomas and gliomas.

Objective:To investigate the expression pattern of pan-TRK protein in colorectal cancers with NTRK gene fusion and mismatch repair deficient (dMMR) and to analyze its molecular pathological characteristics.Methods:A total of 117 dMMR colorectal cancers diagnosed in the Department of Pathology of Henan Provincial People′s Hospital, Zhengzhou, China from 2020 to 2023 were collected. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and DNA/RNA-based next-generation sequencing (NGS) were used to detect pan-TRK protein expression and fusion partner genes in tumors, and to further explore the correlation between pan-TRK staining patterns and partner genes.Results:IHC and FISH were performed successfully in formalin-fixed paraffin-embedded tissues from 117 dMMR colorectal cancer patients. There were 15 (15/117, 12.8%) cases with positive pan-TRK, including 6 cases with strong staining in tumor cell membrane and cytoplasm, 2 cases with weakly granular staining in tumor cytoplasm, 2 cases with moderate dot-like staining in near 5% tumor cell nuclei, 1 case with moderately to strongly granular staining in the cytoplasm and membrane of tumor cells, 1 case with moderately to weakly granular staining in about 60% of the tumor cells, 1 case with strongly staining in about 1% of the tumor cells, 1 case with moderately to strongly staining in about 3% of the tumor cells and 1 case with diffuse, moderate para-nuclear dot-like and weakly perinuclear granular staining. NTRK1 gene disruption was detected in 6 cases (6/117, 5.1%) and consistent with diffusely strong expression of pan-TRK. Based on DNA/RNA NGS, it was further confirmed that the 6 cases with NTRK1 gene disruption all carried TPM3-NTRK1 fusion gene, and all had high microsatellite instability and high tumor mutation burden. No KRAS, NRAS, BRAF V600E or TP53 gene mutations were detected. Four patients carried frame shift mutations in RNF43. Other molecular changes included 3 cases with ROS1 gene mutation, 2 cases with BRAC, ALK, and EGFR gene mutations, 2 cases with ATM gene mutation, and 2 cases with KIT gene mutation. These were missense/frame shift mutations that were associated with no clinical significance. The nine pan-TRK-positive cases without NTRK gene fusion detected with DNA-based NGS were further confirmed with RNA-based NGS, and no NTRK gene fusion was found. The sensitivity and specificity of NTRK gene fusion detected using IHC were 100.0% and 92.5%, respectively. The sensitivity and specificity of diffusely strong membranous/cytoplasmic staining were both 100.0%.Conclusions:Pan-TRK protein has various expression patterns in dMMR colorectal cancer. Its diffusely strong expression is highly suggestive of NTRK1 gene fusion. TPM3-NTRK1 gene fusion is a common form of NTRK gene fusion in dMMR colorectal cancer.

Objective:To investigate the expression pattern of pan-TRK protein in colorectal cancers with NTRK gene fusion and mismatch repair deficient (dMMR) and to analyze its molecular pathological characteristics.Methods:A total of 117 dMMR colorectal cancers diagnosed in the Department of Pathology of Henan Provincial People′s Hospital, Zhengzhou, China from 2020 to 2023 were collected. Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and DNA/RNA-based next-generation sequencing (NGS) were used to detect pan-TRK protein expression and fusion partner genes in tumors, and to further explore the correlation between pan-TRK staining patterns and partner genes.Results:IHC and FISH were performed successfully in formalin-fixed paraffin-embedded tissues from 117 dMMR colorectal cancer patients. There were 15 (15/117, 12.8%) cases with positive pan-TRK, including 6 cases with strong staining in tumor cell membrane and cytoplasm, 2 cases with weakly granular staining in tumor cytoplasm, 2 cases with moderate dot-like staining in near 5% tumor cell nuclei, 1 case with moderately to strongly granular staining in the cytoplasm and membrane of tumor cells, 1 case with moderately to weakly granular staining in about 60% of the tumor cells, 1 case with strongly staining in about 1% of the tumor cells, 1 case with moderately to strongly staining in about 3% of the tumor cells and 1 case with diffuse, moderate para-nuclear dot-like and weakly perinuclear granular staining. NTRK1 gene disruption was detected in 6 cases (6/117, 5.1%) and consistent with diffusely strong expression of pan-TRK. Based on DNA/RNA NGS, it was further confirmed that the 6 cases with NTRK1 gene disruption all carried TPM3-NTRK1 fusion gene, and all had high microsatellite instability and high tumor mutation burden. No KRAS, NRAS, BRAF V600E or TP53 gene mutations were detected. Four patients carried frame shift mutations in RNF43. Other molecular changes included 3 cases with ROS1 gene mutation, 2 cases with BRAC, ALK, and EGFR gene mutations, 2 cases with ATM gene mutation, and 2 cases with KIT gene mutation. These were missense/frame shift mutations that were associated with no clinical significance. The nine pan-TRK-positive cases without NTRK gene fusion detected with DNA-based NGS were further confirmed with RNA-based NGS, and no NTRK gene fusion was found. The sensitivity and specificity of NTRK gene fusion detected using IHC were 100.0% and 92.5%, respectively. The sensitivity and specificity of diffusely strong membranous/cytoplasmic staining were both 100.0%.Conclusions:Pan-TRK protein has various expression patterns in dMMR colorectal cancer. Its diffusely strong expression is highly suggestive of NTRK1 gene fusion. TPM3-NTRK1 gene fusion is a common form of NTRK gene fusion in dMMR colorectal cancer.

Objective:To investigate the clinicopathological and molecular genetic characteristics of well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) with myxoid-like morphology, and to distinguish them from myxofibrosarcoma (MFS) with similar morphology.Methods:Twenty-nine cases of myxoid-like liposarcoma and 5 cases of MFS were collected from Henan Provincial People′s Hospital, Zhengzhou, China and the First Medical Center of PLA General Hospital, Beijing, China from January 2015 to March 2023. Relevant markers were detected using immunohistochemistry and fluorescence in situ hybridization (FISH). The literature was also reviewed.Results:There were 24 males and 10 females, with ages ranging from 41 to 73 years. The tumor sites included retroperitoneum ( n=17), abdomen ( n=9), lower limbs ( n=5), scrotum ( n=1), upper limb ( n=1) and axilla ( n=1). WDLPS was commonly seen as lipomatoid type (12 cases), while the dedifferentiated components of DDLPS included low-grade (13 cases) and high-grade (2 cases) morphology, with low-high grade myxofibrosarcoma, dermatofibrosarcoma protuberans, and low-grade fibrosarcoma structures. Twenty-nine liposarcomas had various proportions of myxoid-like morphology, while 16 showed various degrees of tumor necrosis. The myxoid-like component showed myxoid pleomorphic liposarcoma (MLPS)-like morphology, lobulated growth, characteristic slender, ramified capillary network,"chicken claw-like"morphology, mucus-rich stroma and lung edema-like morphology. Tumor cells were spindle and oval, with many variable vacuolar lipoblasts. MDM2 gene amplification was detected using FISH and present in all tested cases (29/29). DDIT3 break-apart mutation was not detected, but its cluster amplification was present (24/29). Among the MFS cases, one showed cluster amplification (1/5), but no cases showed break-apart or amplification of MDM2 gene. Conclusions:WDLPS/DDLPS with myxoid-like morphology is most commonly seen in the retroperitoneum and abdominal cavity and mostly harbors DDIT3 break-apart probe amplification, while this amplification is not specific to liposarcoma. For core biopsy specimens or very rare tumors in the limbs, when histology has mucinous stroma and MLPS-like morphology, misdiagnosis of MLPS or other non-lipomatous neoplasms with myxoid morphology should be avoided.

The diagnosis of vascular diseases is not only about distinguishing neoplastic or non-neoplastic lesions, but also focusing more on emphasizing the essence of the disease, namely the presence or absence of endothelial cell proliferation, and further to distinguishing true hemangioma tumors or vascular malformation. This article is based on the International Society for the Study of Vascular Anomalies (ISSVA) classification, which is widely used in clinical practice, and discusses the related pathological diagnosis issues of vascular diseases.

Objective:To investigate the clinicopathological features, classification, and genetic characteristics of common lymphatic malformation (CLM) in superficial soft tissue.Methods:A retrospective study of 110 patients with the diagnosis of CLM at the Henan Province People′s Hospital, China from August 2019 to August 2022 was performed. The clinicopathological features, relevant immunohistochemical (IHC) staining results, and fluorescence quantitative PCR of PIK3CA mutation were analyzed, and patients were followed up.Results:Among the 110 CLM patients, there were 53 males and 57 females; 65 cases (65/110, 59.1%) were first detected when the patients were≤2 years old. The most common location was the head and neck in 41 cases (41/110, 37.3%). Clinically, 102 cases (102/110, 92.7%) were solitary, 83 cases (83/110, 75.5%) were skin-colored, 69 cases (69/110, 62.7%) had indistinct borders, and 10 cases (10/110, 9.1%) had diffuse and severe macroscopic manifestations. There were 52 macrocystic type (52/110, 47.3%), 23 microcystic type (23/110, 20.9%), and 35 combined type (35/110, 31.8%). The macrocystic CLM presented as soft, translucent masses with large cystic cavities on the cut surface, and histologically they were composed of large, irregularly dilated channels that were thicker with irregular smooth muscle and lymphocytic infiltration. Microcystic CLM showed wartlike projections or translucent blisters on the skin, with small honeycomb structures on the cut surface, and histologically consisted of round or angular dilated small lymphatic vessels with little or no smooth muscle. The combined CLM had both macrocystic and microcystic morphologies. IHC staining showed that the lymphatic endothelial cells were positive for LYVE-1, D2-40, PROX1, CD31, and VEGFR3 but negative for CD34; in the macrocystic and combined CLM vessel walls were positive for SMA. Eight of 13 CLM had PIK3CA mutation. All patients were followed up, and 24 (24/110, 21.8%) had relapses, which more frequently occurred in combined type, followed by microcystic type.Conclusions:CLM is a congenital vascular malformation composed of dilated, abnormal lymphatic channels, with PIK3CA mutation. There are significant differences in clinicopathological characteristics among the different types. Since microcystic and combined CLM are prone to recurrence, accurate pathological subtyping is necessary to guide treatment and to predict prognosis.

Objective:To investigate the clinicopathological features, molecular genetic features, and differential diagnosis of intraductal carcinomas (IDC) of the salivary glands.Methods:Twenty-five cases of salivary gland IDC diagnosed at the Department of Oral Pathology, Shanghai Ninth People′s Hospital and two cases from Department of Pathology, Henan Provincial People′s Hospital, Zhengzhou, China from January 2008 to July 2023 were collected. Their clinical and pathological features were analyzed retrospectively. Fluorescence in situ hybridization and Sanger sequencing were performed. The patients were followed up and related literatures were reviewed.Results:There were 27 patients with IDC, including 15 males and 12 females, ranging in age from 20.0 to 80.0 years (mean 55.9 years). Clinically, the tumor often presented as a painless mass with a tumor diameter of 1.0-3.0 cm (mean 2.0 cm). All patients received surgical treatment. Twenty patients were followed up. One of them (1/20) died of lung cancer, while the rest survived without tumor recurrence. Histologically, IDC were classified as: intercalated (63.0%, 17/27), apocrine (25.9%, 7/27), oncocytic (7.4%, 2/27) and mixed (3.7%, 1/27) types. Intercalated tumors showed positive S-100 and negative androgen receptor (AR) immunoreactivity. Ki-67 proliferation index was low (about 1%-5%). Nine cases had the RET gene disruption, and 2 cases showed the BRAF V600E mutation. Apocrine tumors showed strong AR immunoreactivity but no S-100 immunoreactivity. Ki-67 proliferation index was high (about 10%-60%), and the RET gene rupture was detected in 1 case. Oncocytic tumors were similar to that of intercalated type in 2 cases, and RET gene disruption was detected in the both cases. Mixed tumors showed histologic features of oncocytic and apocrine patterns and harbored the RET gene disruption.Conclusions:IDC is a rare low-grade malignant tumor of the salivary gland and easily confused with other salivary gland tumors with similar morphology. Molecular testing is helpful for its differential diagnosis.

Objective:To investigate the clinicopathological features and genevariation of sporadic arteriovenous malformation (AVM) in soft tissue.Methods:Eighty cases of soft tissue sporadic AVM diagnosed in Henan Provincial People′s Hospital from January 2017 to March 2022, were retrospectively collected. The relevant indicators were detected by immunohistochemistry and fluorescent quantitative PCR, and the relevant literature was reviewed.Results:There were 42 males and 38 females patients, aged from 4 to 71 years, with a mean age of 26 years.The sites of the disease included head and neck (34 cases), limbs (24 upper limbs, 17 lower limbs) and trunk (5 cases). The main clinical manifestations were characteristic pulsation, tremor, temperature rise, local pain, ulcer or repeated bleeding, and heart failure in severe cases due to long-term hemodynamic abnormalities.Color Doppler ultrasound (CDFI) can detect the high flow characteristics of AVM.Multiple cavitary vascular shadows were seen on MRI. Microscopically, the pathological tissue involved the skin appendages, deep fat and muscle tissue, in which abnormal vascular proliferation was seen, mostly scattered, the lumen was irregularly expanded, the wall thickness was different, but most of them were thick, the vascular wall was glassy and myxoid, inflammatory cell infiltration, bleeding, thrombosis and organization were visible, and calcification was rare.Clustered proliferative muscular small vessels were found around the abnormal blood vessels.No vascular endothelial cell proliferation was found in the blood vessels of the lesion. Immunohistochemistry showed that vascular endothelial cells expressed CD31, CD34 and ERG, and muscle fibers and smooth muscle tissues in the wall expressed SMA.Elastic fiber staining showed incomplete elastic layer in the wall of the malformed artery.PIK3CA gene was detected in 15 cases, and 1 case (1/15) had mutation (mutation rate 6.7%). All cases underwent surgical resection, 73 cases were followed up for 3 months to 5 years, and 15 cases recurred.Conclusions:Sporadic AVM in soft tissue is a typical lesion of vascular malformation with high flow velocity. There are abnormal arteries and clusters of proliferating small vessels.Because of the significant difference in clinical manifestation, treatment and prognosis, pathological diagnosis should be distinguished from congenital hemangioma, intramuscular hemangioma capillary type, PTEN soft tissue hamartoma and common venous malformation.Very few cases may involve PIK3CA gene mutation, suggesting that there may be abnormal PI3K signal pathway in AVM and may participate in the occurrence and development of the disease. AVM has a high recurrence rate and needs long-term follow-up.

Objective:To study the clinicopathological, immunophenotypic and molecular genetic characteristics of nodular fasciitis (NF) in unusual sites.Methods:A total of 50 cases of NF diagnosed between January 2015 and January 2021 were reviewed in the Department of Pathology, Henan Provincial People′s Hospital, and the clinical and pathologic data were analyzed. Among them, 14 cases from unusual sites were included in this study. Immunohistochemical (IHC) staining was used to detect the expression of related proteins, and fluorescence in situ hybridization (FISH) was used to detect the breakage of the USP6 gene.Results:There were seven males and seven females in the 14 NF respectively. The lesions were located in the extremities, perineum, breast, wrist joints, the gap between lumbar vertebra 4/5, and in eight cases there was involvement of unusual tissues (six cases in skeletal muscle, one case in nerve root, and one case was intravascular). The tumor boundary was unclear with infiltrating growth. Spindle-shaped myofibroblasts were arranged in bundles or chaotically, with mild pleomorphic, small nucleoli and various mitotic figures. The tumor stroma showed collagenization to myxoid degeneration with erythrocyte extravasation and infiltration of inflammatory cells. IHC staining showed that the spindle cells expressed SMA focally or partially, and p16 diffusely and strongly. FISH showed that 12 of 14 cases had USP6 gene breakage, and two of them occurred in the intrathoracic skeletal muscle with the red signal amplification of USP6 gene.Conclusions:NF in unusual sites shows similar clinicopathological and genetic characteristics to classic NF, but the tumor mostly has infiltrating borders, non-specific and strong expression of p16, and USP6 red signal amplification. The pathological diagnosis of NF in rare sites should be highly vigilant.