Prognostic Effect of Tertiary Lymphoid Structures in Epstein-Barr Virus-Associated Gastric Carcinomas Measured by Digital Image Analysis.

Epstein-Barr virus-associated gastric carcinoma (EBVaGC) is characterized by prominent tumor-infiltrating lymphocytes (TILs) and has a favorable prognosis. Tertiary lymphoid structures (TLS), characterized by ectopic aggregated lymphocytes with high-endothelial venules (HEV), are associated with favorable outcomes in various solid tumors. We hypothesized that EBVaGC, characterized by intense TILs, may be closely associated with TLS or HEV. To test this hypothesis, we digitally analyzed the TLS, HEV, and TILs in 73 surgically resected advanced EBVaGCs. For HEV, dual MECA-79 and CD31 dual immunohistochemistry were performed, and the ectopic expression of MECA-79 in tumor cells was measured. In 73 patients with EBVaGC, a high-TLS ratio was found in 29 (39.7%) cases, high-tumor-associated HEV density in 44 (60.3%) cases, and high-CD8+ TIL density in 38 (52.1%) cases. Ectopic tumor expression of MECA-79 was observed in 36 patients (49.3%) cases. A low-TLS ratio and tumor-associated HEV density were significantly associated with lymph node metastasis (P = .005 and .042, respectively). Ectopic MECA-79 expression was significantly associated with lymph node metastasis (P = .003). Patients with a low-TLS ratio (P = .038), low-HEV density (P = .042), and ectopic tumor MECA-79 expression (P = .032) had significantly worse prognoses. In conclusion, TLS ratio and HEV density affect the survival of patients with EBVaGC and may be related to the immune response that interrupts lymph node metastasis.

Cerebellar dysfunction and schizophrenia-like behavior in Ebp1-deficient mice.

Cerebellar deficits with Purkinje cell (PCs) loss are observed in several neurologic disorders. However, the underlying mechanisms as to how the cerebellum is affected during development remain unclear. Here we demonstrated that specific inactivation of murine Ebp1 in the central nervous system causes a profound neuropathology characterized by reduced cerebellar volume and PCs loss with abnormal dendritic development, leading to phenotypes including motor defects and schizophrenia (SZ)-like behaviors. Loss of Ebp1 leads to untimely gene expression of Fbxw7, an E3 ubiquitin ligase, resulting in aberrant protein degradation of PTF1A, thereby eliciting cerebellar defects. Reinstatement of Ebp1, but not the Ebp1-E183Ter mutant found in SZ patients, reconstituted cerebellar architecture with increased PCs numbers and improved behavioral phenotypes. Thus, our findings indicate a crucial role for EBP1 in cerebellar development, and define a molecular basis for the cerebellar contribution to neurologic disorders such as SZ.

Roles of ErbB3-binding protein 1 (EBP1) in embryonic development and gene-silencing control.

ErbB3-binding protein 1 (EBP1) is implicated in diverse cellular functions, including apoptosis, cell proliferation, and differentiation. Here, by generating genetic inactivation of Ebp1 mice, we identified the physiological roles of EBP1 in vivo. Loss of Ebp1 in mice caused aberrant organogenesis, including brain malformation, and death between E13.5 and 15.5 owing to severe hemorrhages, with massive apoptosis and cessation of cell proliferation. Specific ablation of Ebp1 in neurons caused structural abnormalities of brain with neuron loss in [Nestin-Cre; Ebp1flox/flox ] mice. Notably, global methylation increased with high levels of the gene-silencing unit Suv39H1/DNMT1 in Ebp1-deficient mice. EBP1 repressed the transcription of Dnmt1 by binding to its promoter region and interrupted DNMT1-mediated methylation at its target gene, Survivin promoter region. Reinstatement of EBP1 into embryo brain relived gene repression and rescued neuron death. Our findings uncover an essential role for EBP1 in embryonic development and implicate its function in transcriptional regulation.

Dysregulation of Epigenetic Control Contributes to Schizophrenia-Like Behavior in Ebp1+/- Mice.

Dysregulation of epigenetic machinery can cause a variety of neurological disorders associated with cognitive abnormalities. In the hippocampus of postmortem Schizophrenia (SZ) patients, the most notable finding is the deregulation of GAD67 along with differential regulation of epigenetic factors associated with glutamate decarboxylase 67 (GAD67) expression. As we previously reported, ErbB3-binding protein 1 (EBP1) is a potent epigenetic regulator. EBP1 can induce repression of Dnmt1, a well-studied transcriptional repressor of GAD67. In this study, we investigated whether EBP1 contributes to the regulation of GAD67 expression in the hippocampus, controlling epigenetic machinery. In accordance with SZ-like behaviors in Ebp1(+/-) mice, heterozygous deletion of EBP1 led to a dramatic reduction of GAD67 expression, reflecting an abnormally high level of Dnmt1. Moreover, we found that EBP1 binds to the promoter region of HDAC1, which leads to histone deacetylation of GAD67, and suppresses histone deacetylase 1 (HDAC1) expression, inversely mirroring an unusually high level of HDAC1 in Ebp1(+/-) mice. However, EBP1 mutant (p.Glu 183 Ter) found in SZ patients did not elevate the expression of GAD67, failing to suppress Dnmt1 and/or HDAC1 expression. Therefore, this data supports the hypothesis that a reduced amount of EBP1 may contribute to an etiology of SZ due to a loss of transcriptional inhibition of epigenetic repressors, leading to a decreased expression of GAD67.

Chaperone-E3 Ligase Complex HSP70-CHIP Mediates Ubiquitination of Ribosomal Protein S3.

In addition to its role in ribosome biogenesis, ribosomal protein S3 (RPS3), a component of the 40S ribosomal subunit, has been suggested to possess several extraribosomal functions, including an apoptotic function. In this study, we demonstrated that in the mouse brain, the protein levels of RPS3 were altered by the degree of nutritional starvation and correlated with neuronal apoptosis. After endurable short-term starvation, the apoptotic function of RPS3 was suppressed by Akt activation and Akt-mediated T70 phosphorylation, whereas after prolonged starvation, the protein levels of RPS3 notably increased, and abundant neuronal death occurred. These events coincided with ubiquitination and subsequent degradation of RPS3, controlled by HSP70 and the cochaperone E3 ligase: carboxy terminus of heat shock protein 70-interacting protein (CHIP). Thus, our study points to an extraribosomal role of RPS3 in balancing neuronal survival or death depending on the degree of starvation through CHIP-mediated polyubiquitination and degradation.

PA2G4/EBP1 ubiquitination by PRKN/PARKIN promotes mitophagy protecting neuron death in cerebral ischemia.

Cerebral ischemia induces massive mitochondrial damage, leading to neuronal death. The elimination of damaged mitochondria via mitophagy is critical for neuroprotection. Here we show that the level of PA2G4/EBP1 (proliferation-associated 2G4) was notably increased early during transient middle cerebral artery occlusion and prevented neuronal death by eliciting cerebral ischemia-reperfusion (IR)-induced mitophagy. Neuron-specific knockout of Pa2g4 increased infarct volume and aggravated neuron loss with impaired mitophagy and was rescued by introduction of adeno-associated virus serotype 2 expressing PA2G4/EBP1. We determined that PA2G4/EBP1 is ubiquitinated on lysine 376 by PRKN/PARKIN on the damaged mitochondria and interacts with receptor protein SQSTM1/p62 for mitophagy induction. Thus, our study suggests that PA2G4/EBP1 ubiquitination following cerebral IR-injury promotes mitophagy induction, which may be implicated in neuroprotection.Abbreviations: AAV: adeno-associated virus; ACTB: actin beta; BNIP3L/NIX: BCL2 interacting protein 3 like; CA1: Cornu Ammonis 1; CASP3: caspase 3; CCCP: carbonyl cyanide m-chlorophenyl hydrazone; DMSO: dimethyl sulfoxide; PA2G4/EBP1: proliferation-associated 2G4; FUNDC1: FUN14 domain containing 1; IB: immunoblotting; ICC: immunocytochemistry; IHC: immunohistochemistry; IP: immunoprecipitation; MCAO: middle cerebral artery occlusion; MEF: mouse embryonic fibroblast; OGD: oxygen-glucose deprivation; PRKN/PARKIN: parkin RBR E3 ubiquitin protein ligase; PINK1: PTEN induced kinase 1; RBFOX3/NeuN: RNA binding fox-1 homolog 3; SQSTM1/p62: sequestosome 1; TIMM23: translocase of inner mitochondrial membrane 23; TOMM20: translocase of outer mitochondrial membrane 20; TUBB: tubulin beta class I; WT: wild-type.

Comparative analysis of ARID1A mutations with mRNA levels and protein expression in gastric carcinoma.

The ARID1A gene is pivotal in chromatin remodeling and genomic integrity and is frequently mutated in various cancer types. ARID1A mutation is the second most frequently mutated tumor suppressor gene and has been suggested as a predictor of immunotherapeutic responsiveness in gastric carcinoma (GC). Despite its significance, the relationship among ARID1A somatic mutations, RNA expression levels, and protein expression remains unclear, particularly in GC. For this purpose, we performed comparative study in two cohorts. Cohort 1 used next-generation sequencing (NGS) to identify 112 GC cases with ARID1A mutations. These cases were compared with ARID1A immunohistochemistry (IHC) results. Cohort 2 employed microarray gene expression data to assess ARID1A RNA levels and compare them with ARID1A IHC results. In Cohort 1, 38.4% of ARID1A-mutated GC exhibited a complete loss of ARID1A protein when assessed by IHC, whereas the remaining 61.6% displayed intact ARID1A. Discordance between NGS and IHC results was not associated with specific mutation sites, variant classifications, or variant allele frequencies. In Cohort 2, 24.1% of the patients demonstrated a loss of ARID1A protein, and there was no significant difference in mRNA levels between the ARID1A protein-intact and -loss groups. Our study revealed a substantial discrepancy between ARID1A mutations detected using NGS and protein expression assessed using IHC in GC. Moreover, ARID1A mRNA expression levels did not correlate well with protein expression. These findings highlighted the complexity of ARID1A expression in GC.

Association of ATM and ARID1A in gastric carcinoma.

BACKGROUND: The ataxia telangiectasia mutated (ATM) gene is involved in the repair of double-stranded DNA breaks and a component of the DNA damage repair pathway. Tumors with mutations or low expression of both ARID1A and ATM exhibit increased numbers of tumor-infiltrating lymphocytes and a favorable prognosis. However, the relationship between ATM and ARID1A in gastric carcinoma (GC) is unclear. METHODS: We used the mRNA expression data from the Asian Cancer Research Group to construct tissue microarrays (N = 249). Next-generation sequencing (NGS) databases of Samsung Medical Center (SMC) (N = 813) were used to compare genetic alterations. Tissue microarrays were used for ATM and ARID1A immunohistochemistry, and expressions were categorized as "low" and "high." NGS data from TCGA-STAD (N = 431) were used as independent cohorts for genetic alterations validation. RESULTS: In GCs, 32.1 % (80/249) of the cases showed low ATM protein expression (ATMlow) and 20.9 % (52/249) showed low ARID1A expression (ARID1Alow). ATMlow was significantly associated with older age (P <.01), gross type of tumor (P =.02), histology (P <. 01), lower incidence of perineural invasion (P =.04), lower disease stage (P <.01), microsatellite instability-high (P <.01), and ARID1Alow (P <.01). Furthermore, GCs in the SMC NGS database showed that ATM mutations were significantly correlated with ARID1A mutations (P <.01), and this finding remained significant in TCGA-STAD validation cohort (P <.01). CONCLUSION: ATMlow in GCs shows a characteristic clinicopathological feature that correlates strongly with ARID1Alow. ATM mutation was also associated with ARID1A mutations, highlighting the interactions between ATM and ARID1A in GC and suggesting a potential therapeutic target.

Neoadjuvant Chemotherapy Response in Triple-Negative Apocrine Carcinoma: Comparing Apocrine Morphology, Androgen Receptor, and Immune Phenotypes.

CONTEXT.­: Apocrine differentiation and androgen receptor (AR) positivity represent a specific subset of triple-negative breast cancer (TNBC) and are often considered potential prognostic or predictive factors. OBJECTIVE.­: To evaluate the response of TNBC to neoadjuvant chemotherapy (NAC) and to assess the impact of apocrine morphology, AR status, Ki-67 labeling index (Ki-67LI), and tumor-infiltrating lymphocytes (TILs). DESIGN.­: A total of 232 TNBC patients who underwent NAC followed by surgical resection in a single institute were analyzed. The study evaluated apocrine morphology and AR and Ki-67LI expression via immunohistochemistry from pre-NAC biopsy samples. Additionally, pre-NAC intratumoral TILs and stromal TILs (sTILs) were quantified from biopsies using a deep learning model. The response to NAC after surgery was assessed based on residual cancer burden. RESULTS.­: Both apocrine morphology and high AR expression correlated with lower Ki-67LI (P < .001 for both). Apocrine morphology was associated with lower postoperative pathologic complete response (pCR) rates after NAC (P = .02), but the difference in TILs between TNBC cases with and without apocrine morphology was not statistically significant (P = .09 for sTILs). In contrast, AR expression did not significantly affect pCR (P = .13). Pre-NAC TILs strongly correlated with postoperative pCR in TNBCs without apocrine morphology (P < .001 for sTILs), whereas TNBC with apocrine morphology demonstrated an indeterminate trend (P = .82 for sTILs). CONCLUSIONS.­: Although TIL counts did not vary significantly based on apocrine morphology, apocrine morphology itself was a more reliable predictor of NAC response than AR expression. Consequently, although apocrine morphology is a rare subtype of TNBC, its identification is clinically important.

The growth of screening-detected pure ground-glass nodules after 10 years of stability.

BACKGROUND: It remains uncertain how long pure ground-glass nodules (pGGNs) detected on low dose computed tomography (LDCT) should be followed. Further studies with longer follow-up periods are needed to determine the optimal follow-up duration for pGGNs. RESEARCH QUESTION: What is the percentage of enlarging nodules among pGGNs that have remained stable for 10 years? STUDY DESIGN AND METHODS: This was a retrospective cohort study originating from subjects with pGGNs detected on LDCT scans between 1997 and 2006, whose natural courses were reported in 2013. We re-analyzed all the follow-up data until July 2022. The study subjects were followed by our institutional guidelines until they were no longer a candidate for definitive treatment. The growth of the pGGNs was defined as an increase in the diameter of the entire nodule by 2 mm or more or the appearance of new solid portions within the nodules. RESULTS: A total of 89 patients with 135 pGGNs were followed for a median of 193 months. Of 135 pGGNs, 23 (17.0%) increased in size, and the median time to the first detection of a size change was 71 months. Of the 23 growing pGGNs, 122 were detected on the first LDCT, and 13 were newly detected on the follow-up CT scan. An increase in size was observed within 5 years in 8 nodules (34.8%), between 5 and 10 years in 12 nodules (52.2%) and after 10 years in 3 nodules (13.0%). Fifteen nodules were histologically confirmed as adenocarcinoma by surgery. Among the 76 pGGNs stable for 10 years, 3 (3.9%) increased in size. INTERPRETATION: Among pGGNs that remained stable for 10 years, 3.9% eventually grew, indicating that some pGGNs can grow even after a long period of stability. We suggest that pGGNs may need to be followed for more than 10 years to confirm growth.

Exploration of drug resistance mechanisms in triple negative breast cancer cells using a microfluidic device and patient tissues.

Chemoresistance is a major cause of treatment failure in many cancers. However, the life cycle of cancer cells as they respond to and survive environmental and therapeutic stress is understudied. In this study, we utilized a microfluidic device to induce the development of doxorubicin-resistant (DOXR) cells from triple negative breast cancer (TNBC) cells within 11 days by generating gradients of DOX and medium. In vivo chemoresistant xenograft models, an unbiased genome-wide transcriptome analysis, and a patient data/tissue analysis all showed that chemoresistance arose from failed epigenetic control of the nuclear protein-1 (NUPR1)/histone deacetylase 11 (HDAC11) axis, and high NUPR1 expression correlated with poor clinical outcomes. These results suggest that the chip can rapidly induce resistant cells that increase tumor heterogeneity and chemoresistance, highlighting the need for further studies on the epigenetic control of the NUPR1/HDAC11 axis in TNBC.

ErbB3 binding protein 1 contributes to adult hippocampal neurogenesis by modulating Bmp4 and Ascl1 signaling.

Neural stem cells (NSCs) in the adult hippocampus divide infrequently; the endogenous molecules modulating adult hippocampal neurogenesis (AHN) remain largely unknown. Here, we show that ErbB3 binding protein 1 (Ebp1), which plays important roles in embryonic neurodevelopment, acts as an essential modulator of adult neurogenic factors. In vivo analysis of Ebp1 neuron depletion mice showed impaired AHN with a low number of hippocampal NSCs and neuroblasts. Ebp1 leads to transcriptional repression of Bmp4 and suppression of Ascl1 promoter methylation in the dentate gyrus of the adult hippocampus reflecting an unusually high level of Bmp4 and low Ascl1 level in neurons of Ebp1-deficient mice. Therefore, our findings suggests that Ebp1 could act as an endogenous modulator of the interplay between Bmp4 and Ascl1/Notch signaling, contributing to AHN.

Comparative Longitudinal Analysis of Malignant Transformation in Pleomorphic Adenoma and Recurrent Pleomorphic Adenoma.

Background: Recurrence in pleomorphic adenoma (PA) has been debated as a risk factor for malignant transformation (MT). In this study, we investigated whether recurrence is a risk factor for MT, by longitudinally analyzing cases with recurrent PA (RPA), and carcinomas from PA (CXPA) or RPA (CXRPA). Methods: The study population included 24 CXPA, 24 RPA, 6 CXRPA, and 386 PA cases (study period 2010−2018). Time and event data were collected from the medical documents to identify the time−event sequences. Results: The time interval to MT in CXRPA was significant longer than that of benign recurrence (median 342.0 vs. 109.5 months). In CXRPA, the recurrence intervals were not shorter than those in RPA according to recurrence frequency. Crudely, the MT rate was 5.9% among primary cases and 20.0% among recurrent cases. However, the time-adjusted MT rates increased up to 11.4% (incubation time > 60 months) and 20.0% (>120 months) in primary cases, which were not different from recurrent cases. Conclusion: In these longitudinal analyses, we did not find any clinical evidence that recurrence facilitates MT in the background of PA. Instead, a long incubation time seems to be a key factor for MT of underlying RPA.

Selection Strategies and Practical Application of BRAF V600E-Mutated Non-Small Cell Lung Carcinoma.

PURPOSE: The incidence of BRAF V600E mutation in non-small cell lung carcinoma (NSCLC) is lower than 2%, which poses difficulties in finding legitimate patients for targeted therapy. We investigated the predictive factors pertaining to BRAF V600E and the effectiveness of the VE1 antibody as a screening method for patient selection. MATERIALS AND METHODS: The study was designed into two steps. In a first group, BRAF-mutated NSCLCs were identified from sequencing data to determine the features of BRAF V600E mutation. The results of the first group helped the collection of adenocarcinomas with a papillary or micropapillary pattern but without EGFR or ALK alterations as a second group so that the frequency of BRAF V600E mutation could be calculated. The sensitivity and specificity of the VE1 were compared with BRAF V600E status. RESULTS: Among 39 BRAF-mutated NSCLCs in the first group, 20 (51%) were V600E. BRAF V600E mutation was more common in female patients and showed no significant correlation with smoking status. Nineteen cases were adenocarcinomas without EGFR and ALK alterations. The most common patterns of invasion were papillary and micropapillary along with central fibrosis. The sensitivity and specificity of the VE1 were 90.0% and 92.3%, respectively. In the second group, 6.7% of cases were VE1-positive, indicating that the prevalence was significantly higher than that reported in previous studies (0.3-1.8%). CONCLUSION: BRAF V600E-mutated NSCLCs could be enriched with the application of clinicopathologic parameters, which are not perfect. Therefore, additional VE1 immunohistochemistry may be useful as a screening method.

EBP1 regulates Suv39H1 stability via the ubiquitin-proteasome system in neural development.

ErbB3-binding protein 1 (EBP1) is a multifunctional protein associated with neural development. Loss of Ebp1 leads to upregulation of the gene silencing unit suppressor of variegation 3-9 homolog 1 (Suv39H1)/DNA (cytosine 5)-methyltransferase (DNMT1). EBP1 directly binds to the promoter region of DNMT1, repressing DNA methylation, and hence, promoting neural development. In the current study, we showed that EBP1 suppresses histone methyltransferase activity of Suv39H1 by promoting ubiquitin-proteasome system (UPS)-dependent degradation of Suv39H1. In addition, we showed that EBP1 directly interacts with Suv39H1, and this interaction is required for recruiting the E3 ligase MDM2 for Suv39H1 degradation. Thus, our findings suggest that EBP1 regulates UPS-dependent degradation of Suv39H1 to govern proper heterochromatin assembly during neural development. [BMB Reports 2021; 54(8): 413-418].

Metastatic leiomyosarcoma of the thyroid gland: cytologic findings and differential diagnosis.

Metastatic leiomyosarcoma to the thyroid is an extremely rare occurrence, and only 18 cases have been reported. Here, we report a case of a 37-year-old woman who presented with multiple masses on the scalp. Excisional biopsy was done and the mass revealed fascicles of smooth muscle fibers which showed positive staining for smooth muscle actin, thus confirming the diagnosis of leiomyosarcoma. The patient was also found to have a 0.9 cm mass within the left thyroid. Fine-needle aspiration was done and the cytological smear showed hypercellular spindle cell clusters with hyperchromatic and large nuclei. Normal thyroid follicular cells were found within or around tumor cells. In this report, we present the cytologic findings of metastatic leiomyosarcoma to the thyroid and offer differential diagnoses of the aspirated spindle cells.

Loss of zinc-finger protein 212 leads to Purkinje cell death and locomotive abnormalities with phospholipase D3 downregulation.

Although Krüppel-associated box domain-containing zinc-finger proteins (K-ZNFs) may be associated with sophisticated gene regulation in higher organisms, the physiological functions of most K-ZNFs remain unknown. The Zfp212 protein was highly conserved in mammals and abundant in the brain; it was mainly expressed in the cerebellum (Cb). Zfp212 (mouse homolog of human ZNF212) knockout (Zfp212-KO) mice showed a reduction in survival rate compared to wild-type mice after 20 months of age. GABAergic Purkinje cell degeneration in the Cb and aberrant locomotion were observed in adult Zfp212-KO mice. To identify genes related to the ataxia-like phenotype of Zfp212-KO mice, 39 ataxia-associated genes in the Cb were monitored. Substantial alterations in the expression of ataxin 10, protein phosphatase 2 regulatory subunit beta, protein kinase C gamma, and phospholipase D3 (Pld3) were observed. Among them, Pld3 alone was tightly regulated by Flag-tagged ZNF212 overexpression or Zfp212 knockdown in the HT22 cell line. The Cyclic Amplification and Selection of Targets assay identified the TATTTC sequence as a recognition motif of ZNF212, and these motifs occurred in both human and mouse PLD3 gene promoters. Adeno-associated virus-mediated introduction of human ZNF212 into the Cb of 3-week-old Zfp212-KO mice prevented Purkinje cell death and motor behavioral deficits. We confirmed the reduction of Zfp212 and Pld3 in the Cb of an alcohol-induced cerebellar degeneration mouse model, suggesting that the ZNF212-PLD3 relationship is important for Purkinje cell survival.

The roles of multifunctional protein ErbB3 binding protein 1 (EBP1) isoforms from development to disease.

The roles of the two isoforms of ErbB3-binding protein 1 (Ebp1) in cellular function and its regulation in disease and development is a stimulating area in current fields of biology, such as neuroscience, cancer biology, and structural biology. Over the last two decades, a growing body of studies suggests have suggested different functions for the EBP1 isoforms in various cancers, along with their specific binding partners in the ubiquitin-proteasome system. Owing to the specific cellular context or spatial/temporal expression of the EBP1 isoforms, either transcriptional repression or the activation function of EBP1 has been proposed, and epigenetic regulation by p48 EBP1 has also been observed during in the embryo development, including in brain development and neurologic disorders, such as schizophrenia, in using an Ebp1 knockout mouse model. Here, we review recent findings that have shaped our current understanding of the emerging function of EBP1 isoforms in cellular events and gene expression, from development to disease.

Superficially Spreading Endocervical Adenocarcinoma in situ with Multifocal Microscopic Involvement of the Endometrial Surface: A Case Report with Emphasis on the Potential for Misdiagnosis Based on Endometrial Curettage Specimens.

Misdiagnosis of endocervical adenocarcinoma (EAC) as endometrial endometrioid carcinoma (EEC) is one of the major concerns when evaluating endometrial curettage specimens. It is difficult to differentiate EAC involving the endometrium from EEC, particularly when the specimens have only a few small tumor fragments. We report a case of endocervical adenocarcinoma in situ (AIS) with multifocal microscopic involvement of the endometrium. The endometrial curettage specimen obtained from an 82-year-old woman consisted of a large volume of blood and fibrin, with small endometrial tissue fragments showing microscopic foci of atypical glandular proliferation. Based on the presence of complex glands with stratified mucin-poor columnar epithelium and intermediate-grade nuclear atypia, a preoperative diagnosis of grade 1 EEC was made. However, the hysterectomy specimen revealed an endocervical AIS involving the endocervix and low uterine segment. Frequent mitotic figures and apoptotic bodies, characteristic of AIS, were present. The endometrium showed a few microscopic foci of atypical glandular proliferation involving the surface only. Their histological features were similar to those of the endocervical AIS. Immunohistochemically, the atypical glands exhibited block p16 positivity. The final diagnosis was a superficially spreading endocervical AIS with multifocal microscopic involvement of the endometrial surface epithelium. In summary, small tumor tissues in an endometrial curettage may lead to misdiagnosis of AIS or EAC as EEC, especially when the pathologists are unaware of the possibility of microscopic endometrial involvement of AIS or EAC. The origin of the tumor can be correctly determined based on a combination of histological features and immunostaining. Endocervical AIS involving the endometrium should be included in the differential diagnosis of neoplastic glandular lesions in endometrial curettage specimens. An accurate diagnosis in these cases is important because of its significant implications for clinical management.

Clinicopathological characteristics of primary lung nuclear protein in testis carcinoma: A single-institute experience of 10 cases.

BACKGROUND: Nuclear protein in testis (NUT) carcinoma is a rare tumor associated with NUT rearrangement that can present as poorly differentiated to undifferentiated carcinoma, with or without abrupt squamous differentiation. It is often misdiagnosed as poorly differentiated carcinoma or undifferentiated carcinoma if NUT is not suspected. In this study, we retrospectively analyzed pulmonary NUT carcinoma cases diagnosed with NUT immunohistochemical staining and discuss the differential diagnosis to provide information for this rare and aggressive entity. METHODS: Cases, diagnosed as "NUT carcinoma" in lung pleura and "metastatic NUT carcinoma from the lung" in lymph nodes were diagnosed between 2017 and 2019 at the Samsung Medical Center (SMC). Clinical features such as age, sex, treatment and follow-up period, and pathological reports were obtained by reviewing patients' electronic medical records. RESULTS: A total of 10 NUT carcinoma cases were found in the SMC pathology database. Seven patients were men and six were non-smokers. Tumor cells showed various cellular features such as round, squamoid, and spindle. Some cases had initially been misdiagnosed as spindle cell neoplasm, round cell sarcoma, squamous cell carcinoma and small cell carcinoma. All cases showed diffuse strong nuclear expression of NUT immunohistochemical staining, and some were positive for p63 staining and negative for CD56 staining. CONCLUSIONS: NUT carcinoma is often misdiagnosed because of its various morphologies. It is important to consider NUT as one of the differential diagnoses when encountering lung biopsy with undifferentiated morphology. KEY POINTS: Due to various morphological features, NUT carcinoma can be misdiagnosed It is important to consider NUT carcinoma when diagnosing a poorly differentiated or undifferentiated tumor.