Keratin 6A Is Expressed at the Invasive Front and Enhances the Progression of Colorectal Cancer.

Keratins (KRTs) are intermediate filament proteins in epithelial cells, and they are important for cytoskeletal organization. KRT6A, classified as a type II KRT, is normally expressed in stratified squamous epithelium and squamous cell carcinomas. Little is known about the expression and role of KRT6A in adenocarcinomas. We investigated the clinicopathologic and molecular biological significance of KRT6A in colorectal adenocarcinoma. Immunostaining of colorectal adenocarcinoma cases treated at our institution demonstrated that KRT6A showed significantly stronger expression at the invasive front than that at the tumor center (P < .0001). The high KRT6A-expression cases (n = 47) tended to have a high budding grade associated with significantly worse prognoses. A multivariate analysis revealed that the KRT6A expression status was an independent prognostic factor for overall survival (P = .0004), disease-specific survival (P = .0097), and progression-free survival (P = .0033). The correlation between KRT6A and patient prognoses was also validated in an external cohort from a published data set. To determine the function of KRT6A in vitro, KRT6A was overexpressed in 3 colon cancer cell lines: DLD-1, SW620, and HCT 116. KRT6A overexpression increased migration and invasion in DLD-1 but did not in SW620 and HCT116. In 3-dimensional sphere-forming culture, KRT6A expression enhanced the irregular protrusion around the spheroid in DLD-1. Our findings in this study indicated that KRT6A expression is a valuable prognostic marker of colorectal cancer and KRT6A may be involved the molecular mechanism in the progression of invasive areas of colorectal cancer.

ECM1 and KRT6A are involved in tumor progression and chemoresistance in the effect of dexamethasone on pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) has a very poor prognosis. Neoadjuvant chemotherapy is an effective PDAC treatment option, but chemotherapy causes unfavorable side effects. Glucocorticoids (e.g., dexamethasone [DEX]) are administered to reduce side effects of chemotherapy for solid tumors, including pancreatic cancer. Glucocorticoids have both beneficial and detrimental effects, however. We investigated the functional changes and gene-expression profile alterations induced by DEX in PDAC cells. PDAC cells were treated with DEX, and the cell proliferation, migration, invasion, and chemosensitivity to gemcitabine (GEM) were evaluated. The results demonstrated decreased cell proliferative capacity, increased cell migration and invasion, and decreased sensitivity to GEM. A comprehensive genetic analysis revealed marked increases in ECM1 and KRT6A in DEX-treated PDAC cells. We evaluated the effects of ECM1 and KRT6A expression by using PDAC cells transfected with those genes. Neither ECM1 nor KRT6A changed the cells' proliferation, but each enhanced cell migration and invasion. ECM1 decreased sensitivity to GEM. We also assessed the clinicopathological significance of the expressions of ECM1 and KRT6A in 130 cases of PDAC. An immunohistochemical analysis showed that KRT6A expression dominated the poorly differentiated areas. High expressions of these two proteins in PDAC were associated with a poorer prognosis. Our results thus demonstrated that DEX treatment changed PDAC cells' functions, resulting in decreased cell proliferation, increased cell migration and invasion, and decreased sensitivity to GEM. The molecular mechanisms of these changes involve ECM1 and KRT6A, whose expressions are induced by DEX.

SMARCB1-deficient malignant neoplasm of the pancreas with heterogeneous morphologies that cannot be classified into existing histologic types.

A 50-year-old male with a pancreatic tail tumor underwent distal pancreatectomy. At 14 and 27 months after the primary surgery, metachronous liver metastases were identified and partial hepatectomies were performed for each. Pathologic findings of the primary pancreatic tumor were heterogeneous, but they essentially categorized into two components based on their cytologic features: (i) clear cell component and (ii) epithelioid cell component. The metastatic hepatic tumor was entirely composed of the epithelioid cell component. SMARCB1 expression was lost by immunohistochemistry and heterozygous deletion of SMARCB1 was identified by fluorescence in situ hybridization for both the primary and metastatic tumors. Targeted DNA sequencing of a metastatic hepatic tumor sample was performed and SMARCB1 loss was identified. Based on the morphologic, immunohistochemical, and molecular analyzes, the present case was difficult to classify into any of the existing entities. SMARCB1 deficiency might play a key role in the tumorigenesis.

Complex glandular pattern is an aggressive morphology that predicts poor prognosis of pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant neoplasm with various morphologies. Recognition of histological patterns that can predict prognosis is important in pathological examination. Recently, the complex glandular pattern was defined as a morphology associating the poor prognosis in lung adenocarcinoma. We investigated the significance of the complex glandular pattern in PDAC by performing a retrospective analysis. Among 240 consecutive cases of conventional PDACs, 21 cases in which complex glandular pattern constituted >50 % of the total tumor volume (CG-PDACs) were identified. The prevalence of CG-PDAC was 8.8 % among all preoperative therapy-naïve and surgically resected conventional PDACs. Compared to the control PDACs (n = 95), the CG-PDACs were characterized by significantly higher prevalence of small- to medium-sized artery invasion (71.4 % vs. 14.7 %, p < 0.0001), intratumoral necrosis (59.1 % vs. 16.8 %, p < 0.0001), tumor budding (mean: 15.5 vs. 12.5 per 0.785 mm2, p = 0.04), significantly higher Ki67 proliferative index (mean: 75.0 % vs. 54.7 %, p < 0.0001), and the HNF1α-/KRT81+ (quasi-mesenchymal) immunophenotype (42.9 % vs. 19.0 %, p = 0.004). In Kaplan-Meier analyses, the CG-PDAC patients achieved significantly worse disease-free survival (DFS) and overall survival (OS) compared to the control PDAC patients; the respective median DFS and OS were 6.3 and 17.7 months for CG-PDACs, and 22.6 and 52.8 months for control PDACs. A multivariate Cox regression analysis showed that predominance of complex glandular pattern was an independent prognostic factor (hazard ratio: 2.95; 95 % confidence interval: 1.46-5.98; p = 0.003). Our results provide new insights into the complex glandular pattern in conventional PDACs as a novel and potentially useful prognostic factor.

Imprint Cytology of Tall Cell Carcinoma with Reversed Polarity of the Breast: A Case Report.

INTRODUCTION: Tall cell carcinoma with reversed polarity (TCCRP) is a rare histologic subtype of breast cancer that was newly categorized in 2020. TCCRP is a relatively novel tumor, and there are no detailed reports about its cellular morphology. We were able to obtain imprint cytological specimens from fresh TCCRP tissue, and we provide our detailed observations. CASE PRESENTATION: The patient was a 73-year-old Japanese female with a 15-mm mass in her right breast. After invasive breast carcinoma was diagnosed based on a core needle biopsy, a lumpectomy was performed. The pathological examination revealed TCCRP, and Sanger sequencing detected IDH2 p.R172M hotspot mutation, which is characteristic of TCCRP. Soon after the surgery, the lumpectomy specimen was sliced before fixation for use in a clinical trial, and imprint cytological materials were obtained from the tumor's cut surface. Cytologically, the tumor showed papillary-like cell clusters and isolated cells with moderate cellularity. Neoplastic cell aggregates and clusters with thick vascular cores as the axis or with delicate fibrovascular stroma were observed. Most of the neoplastic cells were cuboidal-to-columnar in shape, with mildly to moderately irregularly shaped blunt nuclei. Some intranuclear cytoplasmic inclusions and nuclear grooves were present, resembling the nuclear findings of papillary thyroid carcinoma. The most characteristic finding was the columnar cell clusters with apically located nuclei, giving the impression of reversed polarity. CONCLUSION: We described cytological findings in TCCRP, a newly classified rare mammary tumor. Most of the characteristic histologic findings were also observed in imprint cytological specimens. Further studies on practical specimens such as fine-needle aspiration are needed for clinical application.

Neuropathological features of levodopa-responsive parkinsonism in multiple system atrophy: an autopsy case report and comparative neuropathological study.

Background: In typical patients with multiple system atrophy with predominant parkinsonism (MSA-P) levodopa is ineffective. However, there are some of these patients who respond well to levodopa treatment. Levodopa efficacy in MSA-P patients is thought to be related to the degree of putaminal damage, but the pathological causation between the putaminal involvement and levodopa efficacy has not been established in detail. Objective: This study aimed to evaluate the neuropathological features of the nigrostriatal dopaminergic system in a "levodopa-responsive" MSA-P patient in comparison with "levodopa-unresponsive" conventional MSA-P patients. Materials and methods: Clinicopathological findings were assessed in a 53-year-old Japanese man with MSA who presented with asymmetric parkinsonism, levodopa response, and later wearing-off phenomenon. During autopsy, the nigrostriatal pathology of presynaptic and postsynaptic dopaminergic receptor density and α-synuclein status were investigated. The other two patients with MSA-P were examined using the same pathological protocol. Results: Four years after the onset, the patient died of sudden cardiopulmonary arrest. On autopsy, numerous α-synuclein-positive glial cytoplasmic inclusions in the basal ganglia, pons, and cerebellum were identified. The number of neurons in the putamen and immunoreactivity for dopamine receptors were well-preserved. In contrast, significant neuronal loss and decreased dopamine receptor immunoreactivity in the putamen were observed in the "levodopa-unresponsive" MSA-P control patients. These putaminal pathology results were consistent with the findings of premortem magnetic resonance imaging (MRI). All three patients similarly exhibited severe neuronal loss in the substantia nigra and decreased immunoreactivity for dopamine transporter. Conclusion: Levodopa responsiveness in patients with MSA-P may be corroborated by the normal putamen on MRI and the preserved postsynaptic nigrostriatal dopaminergic system on pathological examination. The results presented in this study may provide a rationale for continuation of levodopa treatment in patients diagnosed with MSA-P.

Gastric tumor mimicking bronchial tissue associated with a laryngotracheoesophageal cleft: a case report.

BACKGROUND: Laryngotracheoesophageal cleft (LTEC) is a rare disease in which the larynx and trachea communicate posteriorly to the esophagus. It is often associated with other congenital malformations, particularly gastrointestinal anomalies. Herein, we report a case of LTEC associated with a gastric polypoid lesion in bronchial tissue. CASE PRESENTATION: A gastric mass was detected in a male fetus since week 21 of gestation using fetal ultrasonography. Esophagogastroduodenoscopy performed after birth revealed a pedunculated polypoid lesion of the gastric fornix. The patient experienced frequent vomiting and aspiration pneumonia, which persisted after nasoduodenal tube feeding. Communication between the airway and esophagus was suspected. Laryngoscopy performed 30 days later revealed an LTEC (type III). Partial gastrectomy was performed when the patient was 93 days of age. Histopathological examination revealed tumor consisting of cartilage tissue covered with a layer of respiratory epithelium. CONCLUSION: The gastric tumor associated with LTEC exhibited structures mimicking bronchial tissue. LTEC occurs because of foregut maldevelopment, and the tumorous respiratory tissue in the stomach may have been formed from the same abnormal foregut development event as LTEC.