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Recent studies have documented frequent evolution of clones carrying common cancer mutations in apparently normal tissues, which are implicated in cancer development1, 2, 3. However, our knowledge is still missing with regard to what additional driver events take place in what order, before one or more of these clones in normal tissues ultimately evolve to cancer. Here, using phylogenetic analyses of multiple microdissected samples from both cancer and non-cancer lesions, we show unique evolutionary histories of breast cancers harbouring der(1;16), a common driver alteration found in roughly 20% of breast cancers. The approximate timing of early evolutionary events was estimated from the mutation rate measured in normal epithelial cells. In der(1;16)(+) cancers, the derivative chromosome was acquired from early puberty to late adolescence, followed by the emergence of a common ancestor by the patient’s early 30s, from which both cancer and non-cancer clones evolved. Replacing the pre-existing mammary epithelium in the following years, these clones occupied a large area within the premenopausal breast tissues by the time of cancer diagnosis. Evolution of multiple independent cancer founders from the non-cancer ancestors was common, contributing to intratumour heterogeneity. The number of driver events did not correlate with histology, suggesting the role of local microenvironments and/or epigenetic driver events. A similar evolutionary pattern was also observed in another case evolving from an AKT1-mutated founder. Taken together, our findings provide new insight into how breast cancer evolves.

BACKGROUND: Breast cancer is highly heterogeneous, suggesting that small but relevant subsets have been under-recognized. Rare and mainly triple-negative breast cancers (TNBCs) were recently found to exhibit tuft cell-like expression profiles, including POU2F3, the tuft cell master regulator. In addition, immunohistochemistry (IHC) has identified POU2F3-positive cells in the normal human breast, suggesting the presence of tuft cells in this organ. METHODS: Here, we (i) reviewed previously identified POU2F3-positive invasive breast cancers (n = 4) for POU2F3 expression in intraductal cancer components, (ii) investigated a new cohort of invasive breast cancers (n = 1853) by POU2F3-IHC, (iii) explored POU2F3-expressing cells in non-neoplastic breast tissues obtained from women with or without BRCA1 mutations (n = 15), and (iv) reanalyzed publicly available single-cell RNA sequencing (scRNA-seq) data from normal breast cells. RESULTS: Two TNBCs of the four previously reported invasive POU2F3-positive breast cancers contained POU2F3-positive ductal carcinoma in situ (DCIS). In the new cohort of invasive breast cancers, IHC revealed four POU2F3-positive cases, two of which were triple-negative, one luminal-type, and one triple-positive. In addition, another new POU2F3-positive tumor with a triple-negative phenotype was found in daily practice. All non-neoplastic breast tissues contained POU2F3-positive cells, irrespective of BRCA1 status. The scRNA-seq reanalysis confirmed POU2F3-expressing epithelial cells (3.3% of all epithelial cells) and the 17% that co-expressed the other two tuft cell-related markers (SOX9/AVIL or SOX9/GFI1B), which suggested they were bona fide tuft cells. Of note, SOX9 is also known as the "master regulator" of TNBCs. CONCLUSIONS: POU2F3 expression defines small subsets in various breast cancer subtypes, which can be accompanied by DCIS. The mechanistic relationship between POU2F3 and SOX9 in the breast warrants further analysis to enhance our und

Vasculogenic mesenchymal tumor (VMT), a primitive mesenchymal neoplasm enriched by various-sized atypical vessels, is a new entity that develops in mediastinal germ cell tumors (GCTs) with yolk sac tumor (YST) components after chemotherapy. Notably, patients with VMT in the residual GCT have increased risk of developing sarcomas or hematopoietic malignancies. Here, we report a late-teenage male patient with residual teratoma and high-grade VMT after chemotherapy for a mediastinal mixed GCT, including YST. Whole-exome sequencing revealed biallelic inactivation of TP53 and extensive copy number alterations that suggested whole-genome doubling. The biopsy tissue of the mixed GCT before chemotherapy exhibited overlapping genetic alterations to those in the VMT. Immunohistochemical analyses of the VMT showed that the abnormal vessels were positive for cytokeratin, glypican 3, EZH2, and IMP3. The findings that VMT inherits the genetic alterations of pre-existing mixed GCT and exhibits a partly YST-like immunophenotype might contribute to its clinical aggressiveness.

[Background:] Patients with osteosarcoma who experience relapse or progression [R/P] have a poor prognosis. [Methods:] Data from 30 patients who experienced R/P among 59 with a diagnosis of high-grade osteosarcoma, who were younger than 40 years old between 2000 and 2019, were retrospectively analyzed to identify prognostic and therapeutic factors influencing their outcomes. [Results:] The 5-year overall survival [OS] rates after the last R/P of patients experiencing first [n=30], second [n=14], and third [n=9] R/P were 50.3%, 51.3%, and 46.7%, respectively. Multivariate analysis did not identify any independent risk factors affecting OS. The 5-year PFS rate of the 30 patients after first R/P was 22.4%, and multivariate analysis identified histologic subtype and curative local surgery as independent risk factors influencing PFS. Long [>6 mo] partial response was observed in three patients treated using temozolomide+etoposide, irinotecan+carboplatin, or regorafenib. [Conclusions:] OS rate in the patients with osteosarcoma experiencing R/P included in this study was markedly higher than that reported previously, mainly due to the surgical total removal of tumors, even after subsequent R/P. The recent establishment of salvage chemotherapy or molecular targeted therapy may also increase survival rates in a subgroup of patients.

BACKGROUND: Central neurocytomas usually have a favorable clinical course, and gross total resection (GTR) results in long-term survival. Recurrences of central neurocytomas are usually local, and dissemination is extremely rare. OBSERVATIONS: A 24-year-old man who presented with vomiting was found to have a mass in the right lateral ventricle. After GTR, he received whole-brain irradiation and chemotherapy and had remained disease-free on follow-up for years. The review of the initial tumor revealed central neurocytoma. Seventeen years later, he presented with deterioration of memory, and magnetic resonance imaging showed an enhanced lesion in the left hippocampus. The enhanced lesion was resected, and the histological examination revealed that the tumor was a disseminated atypical central neurocytoma with frequent mitoses. Although he was treated with chemotherapy, the disseminated tumor slowly grew and invaded the brain. Massive brain invasion occurred without enhanced lesions, and he died 27 months after the tumor recurrence. LESSONS: In this patient, a central neurocytoma disseminated after an extremely long period of time. Once neurocytomas disseminate and show aggressive behavior, patients usually follow a poor course. Patients with central neurocytomas should be followed up for a long time.

Donor–recipient human leukocyte antigen (HLA) compatibility has not been considered to significantly affect liver transplantation (LT) outcomes; however, its significance in living-donor LT (LDLT), which is mostly performed between blood relatives, remains unclear. This retrospective cohort study included 1954 LDLTs at our institution (1990–2020). The primary and secondary endpoints were recipient survival and the incidence of T cell–mediated rejection (TCMR) after LDLT, respectively, according to the number of HLA mismatches at all five loci: HLA-A, HLA-B, HLA-C, HLA-DR, and HLA-DQ. Subgroup analyses were also performed in between-siblings that characteristically have widely distributed 0–10 HLA mismatches. A total of 1304 cases of primary LDLTs were finally enrolled, including 631 adults (recipient age at LT ≥18 years) and 673 children (<18 years). In adult-to-adult LDLT, the more HLA mismatches at each locus, the significantly worse the recipient survival was (p = 0.03, 0.01, 0.03, 0.001, and <0.001 for HLA-A, HLA-B, HLA-C, HLA-DR, and HLA-DQ, respectively). This trend was more pronounced when multiple loci were combined (all p < 0.001 for A + B + DR, A + B + C, DR + DQ, and A + B + C + DR + DQ). Notably, a total of three or more HLA-B + DR mismatches was an independent risk factor for both TCMR (hazard ratio [HR] 2.66, 95% confidence interval [CI] 1.21–5.87; p = 0.02) and recipient survival (HR 2.44, 95% CI 1.11–5.35; p = 0.03) in between-siblings. By contrast, HLA mismatch did not affect pediatric LDLT outcomes at any locus or in any combinations; however, it should be noted that all donor–recipient relationships are parent-to-child that characteristically possesses one or less HLA mismatch at each locus and maximally five or less mismatches in total. In conclusion, HLA mismatch significantly affects not only TCMR development but also recipient survival in adult LDLT, but not in children.

Tuft cells are chemosensory epithelial cells in the respiratory tract and several other organs. Recent studies revealed tuft cell-like gene expression signatures in some pulmonary adenocarcinomas, squamous cell carcinomas (SQCC), small cell carcinomas (SCLC), and large cell neuroendocrine carcinomas (LCNEC). Identification of their similarities could inform shared druggable vulnerabilities. Clinicopathological features of tuft cell-like (tcl) subsets in various lung cancer histotypes were studied in two independent tumor cohorts using immunohistochemistry (n = 674 and 70). Findings were confirmed, and additional characteristics were explored using public datasets (RNA seq and immunohistochemical data) (n = 555). Drug susceptibilities of tuft cell-like SCLC cell lines were also investigated. By immunohistochemistry, 10–20% of SCLC and LCNEC, and approximately 2% of SQCC expressed POU2F3, the master regulator of tuft cells. These tuft cell-like tumors exhibited “lineage ambiguity” as they co-expressed NCAM1, a marker for neuroendocrine differentiation, and KRT5, a marker for squamous differentiation. In addition, tuft cell-like tumors co-expressed BCL2 and KIT, and tuft cell-like SCLC and LCNEC, but not SQCC, also highly expressed MYC. Data from public datasets confirmed these features and revealed that tuft cell-like SCLC and LCNEC co-clustered on hierarchical clustering. Furthermore, only tuft cell-like subsets among pulmonary cancers significantly expressed FOXI1, the master regulator of ionocytes, suggesting their bidirectional but immature differentiation status. Clinically, tuft cell-like SCLC and LCNEC had a similar prognosis. Experimentally, tuft cell-like SCLC cell lines were susceptible to PARP and BCL2 co-inhibition, indicating synergistic effects. Taken together, pulmonary tuft cell-like cancers maintain histotype-related clinicopathologic characteristics despite overlapping unique molecular features. From a therapeutic perspective, identification of tuft

The clinical significance of intraductal carcinoma of the prostate (IDC-P) in men with nonmetastatic prostate cancer (PCa) treated with high-dose external-beam radiation therapy remains unclear. The aim of this study was to evaluate the impact of IDC-P in men who received intensity-modulated radiation therapy (IMRT) for nonmetastatic PCa. All patients with high-risk (H-R) and very high–risk (VH-R) PCa who received IMRT between September 2000 and December 2013 at our institution were analyzed retrospectively. We re-reviewed biopsy cores for the presence of IDC-P. Treatment consisted of IMRT (median: 78 Gy at 2 Gy per fraction) plus 6-month neoadjuvant hormonal therapy (HT). In total, 154 consecutive patients with H-R and VH-R PCa were analyzed. Intraductal carcinoma of the prostate was present in 27.9% (n = 43). The median follow-up period was 8.4 years. The 10-year PCa-specific survival, biochemical failure (BF), clinical failure, and castration-resistant PCa rates were 90.0%, 47.8%, 27.5%, and 24.5% in patients with IDC-P, and 96.6%, 32.6%, 10.8%, and 7.0% in those without IDC-P, respectively (p = 0.12, 0.04, 0.0031, and 0.012, respectively). In multivariable analysis, IDC-P was not identified as an independent predictive factor for BF (p = 0.26). The presence of IDC-P was correlated with a significantly higher incidence of disease progression in men with H-R and VH-R PCa who received IMRT, although it was not identified as an independent predictive factor for BF. Further investigations are needed to determine the significance of IDC-P as an independent predictive factor for survival outcomes.

Myxofibrosarcoma (MFS) is a rare subtype of sarcoma, whose genetic basis is poorly understood. We analyzed 69 MFS cases using whole-genome (WGS), whole-exome (WES) and/or targeted-sequencing (TS). Newly sequenced genomic data were combined with additional deposited 116 MFS samples. WGS identified a high number of structural variations (SVs) per tumor most frequently affecting the TP53 and RB1 loci, 40% of tumors showed a BRCAness-associated mutation signature, and evidence of chromothripsis was found in all cases. Most frequently mutated/copy number altered genes affected known disease drivers such as TP53 (56.2%), CDKN2A/B (29.7%), RB1 (27.0%), ATRX (19.5%) and HDLBP (18.9%). Several previously unappreciated genetic aberrations including MUC17, FLG and ZNF780A were identified in more than 20% of patients. Longitudinal analysis of paired diagnosis and relapse time points revealed a 1.2-fold mutation number increase accompanied with substantial changes in clonal composition over time. Our study highlights the genetic complexity underlying sarcomagenesis of MFS.

[Background] Intra-cranial schwannomas account for less than 8% of brain tumors, among which more than 80% arise from the vestibular nerve. Intra-cerebellar schwannomas are extremely rare. Several cases have been previously reported but without remarkable degenerative changes on histology. [Case presentation] A 61-year-old man presented with worsening disorientation, and an imaging study revealed a cystic lesion (6.5 cm in the largest diameter) in the left hemisphere of the cerebellum accompanied by a mural nodule (2.5 cm) located just inside the skull with enhancement and focal calcification, in addition to hydrocephalus. The lesion was more than 5 mm from the left acoustic nerve. The patient underwent gross total resection. Pathological examination revealed remarkable degenerative changes with various morphological features. Tumor cells were pleomorphic with rich cytoplasm containing numerous eosinophilic granules. Blood vessels and extracellular matrix showed remarkable hyalinization. Immunohistochemical staining revealed that the tumor cells were positive for S-100 protein and negative for Olig2. The tumor was diagnosed as a schwannoma with marked degenerative changes. [Conclusions] The present case is discussed with reference to a systematic review of previous reports of intra-cerebellar schwannoma. Intra-cerebellar schwannoma should be included in the differential diagnosis of cystic lesions with heterogeneous histopathological morphology in the cerebellum.

[Background] Tuft cells are chemosensory epithelial cells playing a role in innate immunity. Recent studies revealed cancers with a tuft cell-like gene expression signature in the thorax. We wondered whether this signature might also occur in extrathoracic cancers. [Methods] We examined mRNA expression of tuft cell markers (POU2F3, GFI1B, TRPM5, SOX9, CHAT, and AVIL) in 19 different types of cancers in multiple extrathoracic organs with The Cancer Genome Atlas (TCGA) (N = 6322). Four different extrathoracic cancers in our local archives (N = 909) were analysed by immunohistochemistry. [Results] Twenty-two (0.35%) extrathoracic tumours with co-expression of POU2F3 and other tuft cell markers were identified in various TCGA datasets. Twelve of the 22 “tuft cell-like tumours” shared poor differentiation and a gene expression pattern, including KIT, anti-apoptotic BCL2, and ionocyte-associated genes. In our archival cases, eleven (1.21%) tumours co-expressing POU2F3, KIT, and BCL2 on immunohistochemistry, i.e., were presumable tuft cell-like cancers. In three among five TCGA cohorts, the tuft cell-like cancer subsets expressed SLFN11, a promising biomarker of PARP inhibitor susceptibility. [Conclusions] Tuft cell-like carcinomas form distinct subsets in cancers of many organs. It appears warranted to investigate their shared gene expression signature as a predictive biomarker for novel therapeutic strategies.

The thymic medulla comprises various cell types, including tuft cells that are involved in innate immunity. We recently reported that in Western cohorts of patients, most thymic squamous cell carcinomas (TSQCCs), in contrast to thymomas, exhibit strong and extensive expression of tuft cell markers, including the tuft cell master regulator, POU2F3. On closer inspection of 94 thymomas that cover the full spectrum of thymoma histotypes, we now find by immunohistochemistry that approximately half of types A, AB, and B1 thymomas contain small numbers (< 10%) of cells expressing POU2F3, while most types B2 and B3 thymomas do not (p < 0.05). Further, in rarer types A and AB thymomas with adenoid growth pattern, POU2F3( +) cells formed aggregates and co-expressed KIT, as did the tumor cells in 100% (9/9) of TSQCCs expressing POU2F3. However, the expression of another tuft cell marker, L1CAM, still distinguished TSQCC from the spectrum of thymomas that were all L1CAM-negative. This study is the first to demonstrate the high frequency of POU2F3 expression in an Asian cohort of TSQCCs. The common occurrence of scattered POU2F3( +) cells in types A and AB thymomas hints at their variable degree of medullary differentiation and supports the historical hypothesis of the medullary nature of type A thymomas. Immunohistochemistry of L1CAM may be a valuable tool to differentiate TSQCCs from thymomas.

Background: Cribriform-predominant adenocarcinoma of the lung (Cribri-ADC) is a recently described tumor growth pattern. However, its prognostic impact has not been clearly determined. We analyzed the data of a series of 1, 057 Japanese patients with resected lung adenocarcinoma to identify the clinical significance of Cribri-ADC. Methods: Cribriform pattern (Cribri-p) is defined as invasive back-to-back fused tumor glands with poorly formed glandular spaces or invasive tumor nests comprising tumors cells that produced glandular lumina. We investigated the correlations of Cribri-p and Cribri-ADC with clinicopathological factors as well as disease-free survival (DFS) and overall survival (OS). Results: Cribri-p was present in 217 patients (20.5%) and Cribri-ADC was determined in 25 patients (2.4%). Cribri-p was associated with larger tumor size, pleural invasion, vascular invasion, lymphatic invasion, and spreading through air spaces (STAS) (all, P<0.0001). Cribri-ADC was associated with younger age (P=0.019), vascular invasion (P=0.0025), STAS (P<0.0001), and ALK rearrangement (P=0.012). The DFS curve of patients with Cribri-ADC was identical to that of patients with solid adenocarcinoma; however, the OS curve was located between that of patients with papillary and acinar adenocarcinoma. Of the 10 patients who had tumor recurrences, eight had EGFR mutations or ALK rearrangement, six of whom achieved relatively long survival (median, 64.6, range, 37.4–113 months) following treatment with tyrosine kinase inhibitors (TKIs). In multivariate analysis, Cribri-ADC was not an independent prognostic factor of either recurrence or death. Conclusions: Cribri-ADC is associated with a higher risk of recurrence; however, most patients can be successfully treated with TKIs.

BACKGROUND: Tumors in the pineal region consist of various histological types, and correct diagnosis from biopsy specimens is sometimes difficult. The authors report the case of a patient with a mixed germ cell tumor infiltrating into the pineal gland despite showing no elevation of tumor markers. OBSERVATIONS: An 18-year-old man complained of headache and nausea and showed disturbance of consciousness. Magnetic resonance imaging showed hydrocephalus associated with a cystic pineal tumor. The patient underwent tumor biopsy followed by endoscopic third ventriculostomy for hydrocephalus in a local hospital. A pineocytoma was diagnosed, and the patient was referred to the authors' hospital for treatment. Concentrations of placental alkaline phosphatase, alpha-fetoprotein (AFP), and beta-human chorionic gonadotropin in cerebrospinal fluid were not elevated. However, the authors' review of the tumor specimen revealed some immature cells infiltrating the pineal gland. These cells were positive for AFP, Sal-like protein 4, and octamer-binding transcription factor 3/4; and the diagnosis was changed to mixed germ cell tumor. Chemoradiotherapy was initiated, followed by surgical removal of the residual tumor. LESSONS: Careful examination of all tumor specimens and immunohistochemical analyses are important for accurate diagnosis of pineal tumors.

[Introduction] A histologic grading system for invasive lung adenocarcinoma (ADC) has been proposed by the International Association for the Study of Lung Cancer (IASLC) Pathology Committee in June 2020. This study evaluated the prognostic value of the IASLC histologic grading system (the IASLC system) in a large Japanese cohort. [Methods] We performed comprehensive histologic subtyping using the semiquantitative estimation of five major patterns and complex glandular patterns in patients with a completely resected lung ADC and determined the histologic grade using the IASLC system. Concordance index and receiver-operating characteristic curves were used to evaluate the clinical utility of the IASLC system for recurrence and death; the comparison was performed with the architectural-pattern system (the Arch system) and the grading system on the basis of the two most predominant patterns (the Sica’s system). [Results] Of 1002 patients with invasive ADC, 235 had recurrent disease and 166 died of lung cancer. The concordance index and area under the curve of the IASLC system were 0.777 and 0.807 for recurrence and 0.767 and 0.776 for death, respectively. These were similar to those of the Arch system (0.763 and 0.796 for recurrence, 0.743 and 0.755 for death) and the Sica’s system (0.786 and 0.814 for recurrence, 0.762 and 0.773 for death). [Conclusions] We reported that the IASLC system for invasive lung ADC has prognostic significance by evaluating a large Japanese cohort. We believe that the IASLC grading system will provide physicians with better information for postsurgery treatment.

Angiomatous polyp is a benign, nonneoplastic nasal polyp that accounts for 4-5% of all inflammatory nasal polyps but is rarely reported in the literature. It can grow rapidly and exhibit an aggressive clinical behavior that can simulate malignant sinonasal tumor. We herein report a case of a 13-year-old boy with a rapidly growing angiomatous polyp in the nasal cavity. We had followed up the patient without significant changes for two years, but the tumor had rapidly grown in the last six months. At first, the rapid growth of the tumor and the bone erosion of the maxilla were suggestive of a malignant tumor. However, with preoperative magnetic resonance imaging (MRI) and [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography imaging findings, we established the corrective diagnosis of an angiomatous polyp. After the diagnostic imaging, we performed an endoscopic endonasal surgery and totally resected the tumor without unnecessary excessive surgery. Recognition of this disease that can mimic malignancy is important to avoid excessive surgery such as en bloc resection by craniofacial approach, and we believe that MRI findings can be helpful for the imaging diagnosis.

[Introduction] Evaluating histopathology via machine learning has gained research and clinical interest, and the performance of supervised learning tasks has been described in various areas of medicine. Unsupervised learning of histological images has the advantage of reproducibility for labeling; however, the relationship between unsupervised evaluation and clinical information remains unclear in nephrology. [Methods] We propose an unsupervised approach combining convolutional neural networks (CNNs) and a visualization algorithm to cluster the histological images and calculate the score for patients. We applied the approach to the entire images or patched images of the glomerulus of kidney biopsy samples stained with hematoxylin and eosin obtained from 68 patients with immunoglobulin A nephropathy. We assessed the relationship between the obtained scores and clinical variables of urinary occult blood, urinary protein, serum creatinine (SCr), systolic blood pressure, and age. [Results] The glomeruli of the patients were classified into 12 distinct classes and 10 patches. The output of the fine-tuned CNN, which we defined as the histological scores, had significant relationships with assessed clinical variables. In addition, the clustering and visualization results suggested that the defined clusters captured important findings when evaluating renal histopathology. For the score of the patch-based cluster containing crescentic glomeruli, SCr (coefficient = 0.09, P = 0.019) had a significant relationship. [Conclusion] The proposed approach could successfully extract features that were related to the clinical variables from the kidney biopsy images along with the visualization for interpretability. The approach could aid in the quantified evaluation of renal histopathology.

BACKGROUND: Papillary glioneuronal tumors (PGNTs) are classified as a type of World Health Organization grade I mixed neuronal-glial tumor. Most PGNTs involve cystic formations with mural nodules and solid components in the cerebral hemispheres, and PGNTs occur mainly in young adults. The long-term prognosis of PGNTs remains unclear. OBSERVATIONS: A 38-year-old male had been diagnosed with an arachnoid cyst associated with epilepsy in a local hospital. The initial magnetic resonance imaging (MRI) study showed the tumor as a heterogeneously enhanced nodule in the left postcentral gyrus. Subsequent MRI studies showed slow growth of the tumor for 26 years. He underwent gross total resection to control his epilepsy. The histopathological findings revealed pseudopapillary structures involving hyalinized blood vessels with a single or pseudostratified layer of cuboidal glial cells with round nuclei and scant cytoplasm. At the periphery of the lesion, Rosenthal fibers and acidophilic granule bodies were observed in the gliotic brain tissue. Immunohistochemically, some interpapillary cells were positive for NeuN. On the basis of these findings, the tumor was diagnosed as a PGNT. LESSONS: This PGNT showed slow growth for 26 years. When recognizing a slowly growing tumor in the cerebral hemispheres of relatively young people that is associated with epileptic seizures, PGNT should be considered as a differential diagnosis.

Post-transplant lymphoproliferative disorders (PTLDs) are life-threatening neoplasms after organ transplantation. Because of their rarity and multiple grades of malignancy, the incidence, outcomes, and clinicopathological features affecting patient survival after liver transplantation (LT) remain unclear. We reviewed 1954 LTs in 1849 recipients (1990-2020), including 886 pediatric (<18 years of age) and 963 adult recipients. The following clinicopathological factors were studied: age, sex, liver etiologies, malignancy grades, Epstein-Barr virus status, performance status (PS), Ann Arbor stage, international prognostic index, and histopathological diagnosis. Of 1849 recipients, 79 PTLD lesions (4.3%) were identified in 70 patients (3.8%). After excluding 3 autopsy cases incidentally found, 67 (45 pediatric [5.1%] and 22 adult [2.3%]) patients were finally enrolled. Comorbid PTLDs significantly worsened recipient survival compared with non-complicated cases (P < 0.001). The 3-year, 5-year, and 10-year overall survival rates after PTLD diagnosis were 74%, 66%, and 58%, respectively. The incidence of PTLDs after LT (LT-PTLDs) was significantly higher (P < 0.001) with earlier onset (P = 0.002) in children, whereas patient survival was significantly worse in adults (P = 0.002). Univariate and multivariate analyses identified the following 3 prognostic factors: age at PTLD diagnosis ≥18 years (hazard ratio [HR], 11.2; 95% confidence interval [CI], 2.63-47.4; P = 0.001), PS ≥2 at diagnosis (HR, 6.77; 95% CI, 1.56-29.3; P = 0.01), and monomorphic type (HR, 6.78; 95% CI, 1.40-32.9; P = 0.02). A prognostic index, the “LT-PTLD score, ” that consists of these 3 factors effectively stratified patient survival and progression-free survival (P = 0.003 and <0.001, respectively). In conclusion, comorbid PTLDs significantly worsened patient survival after LT. Age ≥18 years and PS ≥2 at PTLD diagnosis, and monomorphic type are independent prognostic factors, and the LT-PTLD score that

Multilocular thymic cyst (MTC) and germ cell tumors are common diseases that impact the mediastinum. Correctly diagnosing these diseases can be difficult because several other conditions can mimic them. We report a male patient with MTC associated with mediastinal seminoma. A needle biopsy of the mediastinal tumor revealed numerous epithelioid cell granulomas that mimicked sarcoidosis or mycobacterial infection. However, large atypical cells positive for Oct3/4 and KIT were noted between the granulomas; thus, we diagnosed the patient with mediastinal seminoma. The resected tumor, after chemotherapy, consisted of multiple cystic lesions, and a residual germ cell tumor was first considered. However, thymic medulla-specific elements, namely, POU2F3-positive thymic tuft cells and rhabdomyomatous myoid cells accompanying the epithelium, led to the correct diagnosis of MTC. Our case underscores the importance of recognizing the histological features associated with mediastinal seminoma and provides novel findings for MTC pathogenesis, namely, the presence of thymic tuft cells.

The neonatal Fc receptor (FcRn) plays a role in trafficking IgG and albumin and is thought to mediate intravenous immunoglobulin (IVIG) therapy for certain diseases. IVIG can be used for the treatment of human Langerhans cell histiocytosis (LCH); however, the mechanism remains unclear. The expression and function of FcRn protein have not been studied in LCH, though the expression of FcRn messenger RNA (mRNA) have been reported. In this report, we confirmed the expression of FcRn in 26 of 30 pathological cases (86.7%) diagnosed immunohistochemically as LCH. The expression was independent of age, gender, location, multi- or single-system, and the status of BRAFV600E immunostaining. We also confirmed the expression of FcRn mRNA and protein in the human LCH-like cell line, ELD-1. FcRn suppressed albumin consumption and growth of IVIG preparation-treated ELD-1 cells, but not of IVIG preparation-untreated or FcRn-knockdown ELD-1 cells. In addition, FITC-conjugated albumin was taken into Rab11-positive recycle vesicles in mock ELD-1 cells but not in FcRn-knockdown ELD-1 cells. IVIG preparation prolonged this status in mock ELD-1 cells. Therefore, ELD-1 recycled albumin via FcRn and albumin was not used for metabolism. Our results increase our understanding of the molecular mechanism of IVIG treatment of LCH.

Even though it is a rare subtype, identifying the genetic features of thymic adenocarcinoma is valuable for a multifaceted understanding of thymic epithelial tumors. We experienced a female patient with thymic adenocarcinoma associated with thymic cysts. The tumor consisted of a solid whitish lesion (lesion-1) and a large cystic lesion with small papillary nodules (lesion-2). Microscopically, lesion-1 exhibited poorly differentiated adenocarcinoma accompanying numerous inflammatory cell infiltrates, and lesion-2 (the nodules within the cystic lesion) exhibited enteric-type adenocarcinoma. Consistent with the histological difference, whole-exome sequencing revealed that these two components exhibited distinct genetic features, except for only a few shared mutations, including CDKN2A truncation. Lesion-1 exhibited microsatellite instability-high signature with high mutation burden, for which immune checkpoint inhibitors might apply; and lesion-2 exhibited whole-genome doubling with KRAS hotspot mutation. Our case presents novel genetic features of thymic adenocarcinoma and demonstrates that distinct mutational processes can be operative within a single tumor.

Desmoid-type fibromatosis (DF) is a locally aggressive but non-metastatic (myo)fibroblastic neoplasm. A hallmark of the tumor is nuclear positivity for beta-catenin in immunohistochemistry due mostly to CTNNB1 mutations. However, a recent study has reported that even beta-catenin ‘nuclear-negative’ DFs can harbor CTNNB1 mutations and that the positive ratio of nuclear beta-catenin in DF is different among antibodies. Here, we reviewed soft tissue lesions for which the possibility of DF was considered and compared the sensitivity and specificity of nuclear beta-catenin for the diagnosis of DF among commonly used anti-beta-catenin antibodies, i.e., clone beta-catenin 1, 17C2 and 14. We analyzed 26 cases of DF, 28 cases of benign fibroblastic lesions, and 27 cases of other soft tissue tumors. The sensitivity and specificity of nuclear beta-catenin for the diagnosis of DF were different among antibodies; 54% and 98% in clone beta-catenin 1, 85% and 84% in 17C2, and 96% and 62% in 14. IHC of LEF1 showed comparable results with IHC of beta-catenin, with a sensitivity of 88% and specificity of 76%. Additionally, when beta-catenin 1 was used, DFs showed characteristic dotted cytoplasmic staining, often appearing as rings. Our results might be helpful for making a correct diagnosis of DF.

The squamous-columnar junction (SCJ) is a boundary consisting of precisely positioned transitional epithelium between the squamous and columnar epithelium. Transitional epithelium is a hotspot for precancerous lesions, and is therefore clinically important; however, the origins and physiological properties of transitional epithelium have not been fully elucidated. Here, by using mouse genetics, lineage tracing, and organoid culture, we examine the development of the SCJ in the mouse stomach, and thus define the unique features of transitional epithelium. We find that two transcription factors, encoded by Sox2 and Gata4, specify primitive transitional epithelium into squamous and columnar epithelium. The proximal-distal segregation of Sox2 and Gata4 expression establishes the boundary of the unspecified transitional epithelium between committed squamous and columnar epithelium. Mechanistically, Gata4-mediated expression of the morphogen Fgf10 in the distal stomach and Sox2-mediated Fgfr2 expression in the proximal stomach induce the intermediate regional activation of MAPK/ERK, which prevents the differentiation of transitional epithelial cells within the SCJ boundary. Our results have implications for tissue regeneration and tumorigenesis, which are related to the SCJ.

The most recurrent fusion of central nervous system high-grade neuroepithelial tumor with MN1 alteration (HGNET-MN1) is MN1 rearrangement. Here, we report the case of a 36-year-old man with spinal cord astroblastoma showing Ewing Sarcoma breakpoint region 1/EWS RNA-binding protein 1 (EWSR1)-BEN domain-containing 2 (BEND2) fusion. The patient presented with back pain, gait disturbance and dysesthesia in the lower extremities and trunk. Magnetic resonance imaging showed an intramedullary tumor at the T3-5 level, displaying homogeneous gadolinium enhancement. Partial tumor removal was performed with laminectomy. Histological examinations demonstrated solid growth of epithelioid tumor cells showing high cellularity, a pseudopapillary structure, intervening hyalinized fibrous stroma, and some mitoses. Astroblastoma was diagnosed, classified as HGNET-MN1 by the German Cancer Research Center methylation classifier. MN1 alteration was not detected by fluorescence in situ hybridization (FISH), but EWSR1-BEND2 fusion was detected by FISH and RNA sequencing. Previously, a child with EWSR1-BEND2 fusion-positive spinal astroblastoma classified as HGNET-MN1 was reported. In conjunction with that, the present case provides evidence that EWSR1-BEND2 fusion is identified in the entity of HGNET-MN1. Taken together, the BEND2 alteration rather than MN1 may determine the biology of a subset of the central nervous system HGNET-MN1 subclass.

Langerhans cell sarcoma (LCS) is a high‐grade neoplasm with overtly malignant cytological features and a Langerhans cell phenotype. The underlying genetic features are poorly understood, and only a few alterations, such as those of the MARK pathway‐related genes, CDKN2A and TP53 have been reported. Here we present a 70‐year‐old male with LCS on the scalp and pulmonary metastasis. The multinodular tumor, 3.0 cm in diameter, consisted of diffusely proliferated pleomorphic cells with numerous mitoses (53/10 HPFs). Immunohistochemically, the tumor cells were positive for CD1a, Langerin and PD‐L1, and the Ki‐67 labeling index was 50%. These pathological features were consistent with LCS, and were also observed in the metastatic tumor. Whole‐exome sequencing revealed that both the primary and metastatic tumors harbored a large number of mutations (>20 mutations/megabase), with deletion of CDKN2A and TP53 mutation, and highlighted that the mutational signature was predominantly characteristic of ultraviolet (UV) exposure (W = 0.828). Our results suggest, for the first time, that DNA damage by UV could accumulate in Langerhans cells and play a role in the pathogenesis of LCS. The high mutational burden and PD‐L1 expression in the tumor would provide a rationale for the use of immune checkpoint inhibitors for treatment of unresectable LCS.

Signaling lymphocytic activation molecule family member 8 (SLAMF8), B-lymphocyte activator macrophage expressed/CD353 is a member of the CD2 family. SLAMF8 suppresses macrophage function but enhances the growth of neoplastic mast cells via SHP-2. In this study, we found that some anaplastic large cell lymphoma (ALCL) samples were immunohistochemically positive for SLAMF8. However, we found no significant differences between SLAMF8-positive and SLAMF8-negative ALCL samples with respect to age, gender, site, or prognosis. We also identified SLAMF8 expression in ALCL cell lines, Karpas299, and SU-DHL-1. SLAMF8 knockdown decreased the activation of SHP-2 and the growth of these cell lines, and increased the apoptosis of these cell lines. In addition, we observed the interaction between SLAMF8 and SHP-2 in these cell lines using the DuoLink in situ kit. Taken together, these results suggest that SLAMF8 may enhance the growth of ALCL via SHP-2 interaction.

Immunohistochemically p16 (CDKN2A)‐negative uterine cervical squamous cell carcinoma (SCC) is uncommon, and there are few reports about its pathological features. This study explored the causes of p16 negativity in such cases. We analyzed diagnostic tissue samples of five cases of p16‐negative cervical SCC among 107 patients who underwent hysterectomy at Kyoto University Hospital between January 2010 and December 2015. The samples were subjected to immunohistochemical staining, in situ hybridization and a genetic analysis. Two of five cases were positive for human papilloma virus (HPV) by genotyping. One was positive for HPV56 with promoter hypermethylation of CDKN2A and co‐existing Epstein–Barr virus infection. Another was positive for HPV6 categorized as low‐risk HPV with condylomatous morphology. Among the remaining three cases, one had amplification of the L1 gene of HPV with promoter hypermethylation of CDKN2A and TP53 mutation, and one of the other two HPV‐negative cases had a homozygous CDKN2A deletion, while the other was positive for p53 and CK7. p16‐negativity of cervical SCC is often associated with an unusual virus infection status and CDKN2A gene abnormality.

Tertiary lymphoid tissues (TLTs) are inducible ectopic lymphoid tissues in chronic inflammatory states and function as sites of priming local immune responses. We previously demonstrated that aged but not young mice exhibited multiple TLTs after acute kidney injury and that TLTs were also detected in human aged and diseased kidneys. However, the forms of progression and the implication for kidney injury remain unclear. To clarify this we analyzed surgically resected kidneys from aged patients with or without chronic kidney disease as well as kidneys resected for pyelonephritis, and classified TLTs into three distinct developmental stages based on the presence of follicular dendritic cells and germinal centers. In injury-induced murine TLT models, the stages advanced with the extent of kidney injury, and decreased with dexamethasone accompanied with improvement of renal function, fibrosis and inflammation. Kidneys from aged patients with chronic kidney disease consistently exhibited more frequent and advanced stages of TLTs than those without chronic kidney disease. Kidneys of patients with pyelonephritis exhibited more frequent TLTs with more advanced stages than aged kidneys. Additionally, TLTs in both cohorts shared similar locations and components, suggesting that TLT formation may not be a disease-specific phenomenon but rather a common pathological process. Thus, our findings provide the insights into biological features of TLT in the kidney and implicate TLT stage as a potential marker reflecting local injury and inflammation.

Killer immunoglobulin-like receptor (KIR) 2DL4 (CD158d) was previously thought to be a human NK cell-specific protein. Mast cells are involved in allergic reactions via their KIT-mediated and FcɛRI-mediated responses. We recently detected the expression of KIR2DL4 in human cultured mast cells established from peripheral blood of healthy volunteers (PB-mast), in the human mast cell line LAD2, and in human tissue mast cells. Agonistic antibodies against KIR2DL4 negatively regulate the KIT-mediated and FcɛRI-mediated responses of PB-mast and LAD2 cells. In addition, agonistic antibodies and human leukocyte antigen (HLA)-G, a natural ligand for KIR2DL4, induce the secretion of leukemia inhibitory factor and serine proteases from human mast cells, which have been implicated in pregnancy establishment and cancer metastasis. Therefore, KIR2DL4 stimulation with agonistic antibodies and recombinant HLA-G protein may enhance both processes, in addition to suppressing mast-cell-mediated allergic reactions.

Chronic inflammation is accompanied by recurring cycles of tissue destruction and repair and is associated with an increased risk of cancer1, 2, 3. However, how such cycles affect the clonal composition of tissues, particularly in terms of cancer development, remains unknown. Here we show that in patients with ulcerative colitis, the inflamed intestine undergoes widespread remodelling by pervasive clones, many of which are positively selected by acquiring mutations that commonly involve the NFKBIZ, TRAF3IP2, ZC3H12A, PIGR and HNRNPF genes and are implicated in the downregulation of IL-17 and other pro-inflammatory signals. Mutational profiles vary substantially between colitis-associated cancer and non-dysplastic tissues in ulcerative colitis, which indicates that there are distinct mechanisms of positive selection in both tissues. In particular, mutations in NFKBIZ are highly prevalent in the epithelium of patients with ulcerative colitis but rarely found in both sporadic and colitis-associated cancer, indicating that NFKBIZ-mutant cells are selected against during colorectal carcinogenesis. In further support of this negative selection, we found that tumour formation was significantly attenuated in Nfkbiz-mutant mice and cell competition was compromised by disruption of NFKBIZ in human colorectal cancer cells. Our results highlight common and discrete mechanisms of clonal selection in inflammatory tissues, which reveal unexpected cancer vulnerabilities that could potentially be exploited for therapeutics in colorectal cancer.

Background: Small cell lung cancer (SCLC) is normally diagnosed with hematoxylin and eosin stains, although some cases require immunohistochemistry (IHC). P40 is highly sensitive and specific for squamous cell carcinoma and is thus considered the best marker for this cancer. However, the status of p40 expression in SCLC is not well known. The aim of this study was to analyze p40 expression in resected SCLC using IHC. Methods: Forty‐four surgically resected SCLC cases were enrolled. Clinical data were obtained from the patients’ medical records. Pathologists blinded to the patients’ clinical data reviewed the SCLC slides. IHC was performed on a representative slide of each case. Results: Although p40 was not diffusely expressed in any of the SCLC cases, p40‐positive cells were observed in the tumors in 15 cases (34.1%). Ten of these exhibited p40 in < 1% of tumor cells. In the remaining five cases, 1–5% of tumor cells expressed p40, and in three of these, the cells expressing p40 also expressed TTF‐1 and neuroendocrine markers. There was no statistically significant relationship between p40 positivity and any other clinicopathological characteristics. Conclusions: Some resected SCLCs express p40 focally. This result suggests that the presence of positive p40 cells does not exclude a diagnosis of SCLC. Thus, small biopsy or cytology specimens with p40‐positive cells must be diagnosed carefully.

This study aimed to identify the characteristics of the vascular network in the superficial subcutaneous layer of the breast and to analyze differences between breasts with cancer and contralateral unaffected breasts using vessel branching points (VBPs) detected by three-dimensional photoacoustic imaging with a hemispherical detector array. In 22 patients with unilateral breast cancer, the average VBP counts to a depth of 7 mm below the skin surface were significantly greater in breasts with cancer than in the contralateral unaffected breasts (p < 0.01). The ratio of the VBP count in the breasts with cancer to that in the contralateral breasts was significantly increased in patients with a high histologic grade (p = 0.03), those with estrogen receptor-negative disease (p < 0.01), and those with highly proliferative disease (p < 0.01). These preliminary findings indicate that a higher number of VBPs in the superficial subcutaneous layer of the breast might be a biomarker for primary breast cancer.

The faithful shutdown of the somatic program occurs in the early stage of reprogramming. Here, we examined the effect of in vivo reprogramming on Kras-induced cancer development. We show that the transient expression of reprogramming factors (1–3 days) in pancreatic acinar cells results in the transient repression of acinar cell enhancers, which are similarly observed in pancreatitis. We next demonstrate that Kras and p53 mutations are insufficient to induce ERK signaling in the pancreas. Notably, the transient expression of reprogramming factors in Kras mutant mice is sufficient to induce the robust and persistent activation of ERK signaling in acinar cells and rapid formation of pancreatic ductal adenocarcinoma. In contrast, the forced expression of acinar cell-related transcription factors inhibits the pancreatitis-induced activation of ERK signaling and development of precancerous lesions in Kras-mutated acinar cells. These results underscore a crucial role of dedifferentiation-associated epigenetic regulations in the initiation of pancreatic cancers.

Advances in next-generation sequencing (NGS) technologies have enabled physicians to test for genomic alterations in multiple cancer-related genes at once in daily clinical practice. In April 2015, we introduced clinical sequencing using an NGS-based multiplex gene assay (OncoPrime) certified by the Clinical Laboratory Improvement Amendment. This assay covers the entire coding regions of 215 genes and the rearrangement of 17 frequently rearranged genes with clinical relevance in human cancers. The principal indications for the assay were cancers of unknown primary site, rare tumors, and any solid tumors that were refractory to standard chemotherapy. A total of 85 patients underwent testing with multiplex gene assay between April 2015 and July 2016. The most common solid tumor types tested were pancreatic (n = 19; 22.4%), followed by biliary tract (n = 14; 16.5%), and tumors of unknown primary site (n = 13; 15.3%). Samples from 80 patients (94.1%) were successfully sequenced. The median turnaround time was 40 days (range, 18–70 days). Potentially actionable mutations were identified in 69 of 80 patients (86.3%) and were most commonly found in TP53 (46.3%), KRAS (23.8%), APC (18.8%), STK11 (7.5%), and ATR (7.5%). Nine patients (13.0%) received a subsequent therapy based on the NGS assay results. Implementation of clinical sequencing using an NGS-based multiplex gene assay was feasible in the clinical setting and identified potentially actionable mutations in more than 80% of patients. Current challenges are to incorporate this genomic information into better therapeutic decision making.

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is expressed in a number of tumor cell types. The immunoreceptor tyrosine-based inhibitory motif (ITIM)-containing isoforms of this molecule which possess a long cytoplasmic tail (CEACAM1-L) generally play inhibitory roles in cell function by interacting with Src homology 2 domain-containing tyrosine phosphatase (SHP)-1 and/or SHP-2. Src family kinases (SFKs) are also known to bind to and phosphorylate CEACAM1-L isoforms. Here, we report that CEACAM1 was uniquely expressed at high levels in both human neoplastic mast cells (mastocytosis) and medullary thyroid carcinoma cell (MTC) lines, when compared with their expression in nonneoplastic mast cells or nonneoplastic C cells. This expression was mainly derived from CEACAM1-L isoforms based upon assessment of CEACAM1 mRNA expression. CEACAM1 knockdown upregulated cell growth of HMC1.2 cells harboring KIT mutations detected in clinical mastocytosis, whereas downregulated the growth of TT cells harboring RET mutations detected in clinical MTCs. Immunoblotting, ELISA and immunoprecipitaion analysis showed that activated SHP-1 is preferentially associated with CEACAM1 in HMC1.2 cells harboring KIT mutations, whereas Src family kinases (SFKs) are preferentially associated with CEACAM1 in TT cells harboring RET mutations. These studies suggest that the dominantly interacting proteins SHP1 or SFK determine whether CEACAM1-L displays a positive or negative role in tumor cells.

Primary central nervous system lymphoma (PCNSL) is a distinct subtype of extranodal lymphoma with aggressive clinical course and poor outcome. As increased IL-10/IL-6 ratio is recognized in the cerebrospinal fluid (CSF) of PCNSL patients, we hypothesized that PCNSL might originate from a population of B cells with high IL-10-producing capacity, an equivalent of "regulatory B cells" in mice. We intended in this study to clarify whether Tim-1, a molecule known as a marker for regulatory B cells in mice, is expressed in PCNSL. By immunohistochemical analysis, Tim-1 was shown to be positive in as high as 54.2% of PCNSL (26 of 58 samples), while it was positive in 19.1% of systemic diffuse large B-cell lymphoma (DLBCL) samples (17 of 89 samples; P < 0.001). Tim-1 expression positively correlated with IL-10 expression in PCNSL (Cramer's V = 0.55, P < 0.001), and forced expression of Tim-1 in a PCNSL cell line resulted in increased IL-10 secretion, suggesting that Tim-1 is functionally linked with IL-10 production in PCNSL. Moreover, soluble Tim-1 was detectable in the CSF of PCNSL patients, and was suggested to parallel disease activity. In summary, PCNSL is characterized by frequent Tim-1 expression, and its soluble form in CSF may become a useful biomarker for PCNSL.

Acute kidney injury (AKI) is a common clinical condition defined as a rapid decline in kidney function. AKI is a global health burden, estimated to cause 2 million deaths annually worldwide. Unlike AKI in the young, which is reversible, AKI in the elderly often leads to end-stage renal disease, and the mechanism that prevents kidney repair in the elderly is unclear. Here we demonstrate that aged but not young mice developed multiple tertiary lymphoid tissues (TLTs) in the kidney after AKI. TLT size was associated with impaired renal function and increased expression of proinflammatory cytokines and homeostatic chemokines, indicating a possible contribution of TLTs to sustained inflammation after injury. Notably, resident fibroblasts from a single lineage diversified into p75 neurotrophin receptor[+] (p75NTR[+]) fibroblasts and homeostatic chemokine–producing fibroblasts inside TLTs, and retinoic acid–producing fibroblasts around TLTs. Deletion of CD4[+] cells as well as late administration of dexamethasone abolished TLTs and improved renal outcomes. Importantly, aged but not young human kidneys also formed TLTs that had cellular and molecular components similar to those of mouse TLTs. Therefore, the inhibition of TLT formation may offer a novel therapeutic strategy for AKI in the elderly.

The hepatocyte paraffin 1 (Hep Par 1) antibody is widely used as a hepatocyte marker, recognizing carbamoyl phosphate synthetase 1 (CPS1), an essential component of the urea cycle. Various missense, nonsense, and frameshift mutations occur in the CPS1 gene. In neonatal patients with homozygous CPS1 deficiency (CPS1D), urea cycle defects with resulting severe hyperammonemia can be fatal, though liver transplantation provides a complete cure for CPS1D. We performed Hep Par 1 immunostaining in the explanted livers of 10 liver transplant patients with CPS1D. Seven were negative for Hep Par 1 in the hepatocytes and the other three showed normal diffuse granular cytoplasmic staining. As expected, all three Hep Par 1-positive patients had at least one missense mutation, and all four patients who had only nonsense or frameshift mutations were Hep Par 1-negative. The other three patients were unexpectedly negative for Hep Par 1, even though each had one missense mutation. These results suggest that CPS1D can be related to the loss of Hep Par 1 reactivity due to the loss of protein production, a one amino acid substitution resulting in an abortive protein product, or both. Hep Par 1 immunohistochemistry can be used as a simple method to confirm CPS1D.

The epithelial-mesenchymal transition (EMT) and cancer stemness (CS) are reported to be pivotal phenomena involved in metastasis, recurrence, and drug-resistance in lung cancer; however, their effects on tumor malignancy in clinical settings are not completely understood. The mutual association between these factors also remains elusive and are worthy of investigation. The purpose of this study was to elucidate the association between EMT and CS, and their effect on the prognosis of patients with lung adenocarcinoma. A total of 239 lung adenocarcinoma specimens were collected from patients who had undergone surgery at Kyoto University Hospital from January 2001 to December 2007. Both EMT (E-cadherin, vimentin) and CS (CD133, CD44, aldehyde dehydrogenase) markers were analyzed through immunostaining of tumor specimens. The association between EMT and CS as well as the patients' clinical information was integrated and statistically analyzed. The molecular expression of E-cadherin, vimentin, and CD133 were significantly correlated with prognosis (P = 0.003, P = 0.005, and P < 0.001). A negative correlation was found between E-cadherin and vimentin expression (P < 0.001), whereas, a positive correlation was found between vimentin and CD133 expression (P = 0.020). CD133 was a stronger prognostic factor than an EMT marker. Elevated CD133 expression is the signature marker of EMT and CS association in lung adenocarcinoma. EMT and CS are associated in lung adenocarcinoma. Importantly, CD133 is suggested to be the key factor that links EMT and CS, thereby exacerbating tumor progression.

Introduction: Pulmonary spindle cell carcinoma (SpCC) is a rare subtype of non-small-cell lung cancer (NSCLC) and, in general, is chemoresistance. Case: A sixty-five year-old male patient with metastatic pulmonary SpCC was initially treated with cisplatin and docetaxel, but his disease progressed. Then, he received a combination chemotherapy with carboplatin and nab-PTX followed by maintenanced chemotherapy with nab-PTX. Fluorodeoxyglucose (FDG) positron-emission CT revealed a substantial decrease of FDG accumulation in the primary tumor, and the response continued for more than 7 months. Discussion: Preclinical models suggested that nab-PTX may reach the tumor microenvironment more efficiently than solvent-based paclitaxel (sb-PTX) and be preferentially taken up by cancer cells. Considering that there is no effective treatment for patients with pulmonary SpCC, nab-PTX may merit further investigation in patients with pulmonary SpCC.

Background: Trogocytosis is defined as the transfer of cell-surface membrane proteins and membrane patches from one cell to another through contact. It is reported that human epidermal growth factor receptor 2 (HER2) could be transferred from cancer cells to monocytes via trogocytosis; however, the clinical significance of this is unknown. The aim of this study is to demonstrate the presence and evaluate the clinical significance of HER2+ tumor-infiltrated immune cells (arising through HER2 trogocytosis) in HER2-overexpressing (HER2+) breast cancer patients receiving trastuzumab-based primary systemic therapy (PST). Methods: To assess the trogocytosis of HER2 from cancer cells to immune cells, and to evaluate the up- and down-regulation of HER2 on immune and cancer cells, peripheral blood mononuclear cells from healthy volunteers and breast cancer patients were co-cultured with HER2+ and HER2-negative breast cancer cell lines with and without trastuzumab, respectively. The correlation between HER2 expression on tumor-infiltrated immune cells and a pathological complete response (pCR) in HER2+ breast cancer patients treated with trastuzumab-based PST was analyzed. Results: HER2 was transferred from HER2+ breast cancer cells to monocytes and natural killer cells by trogocytosis. Trastuzumab-mediated trogocytosed-HER2+ effector cells exhibited greater CD107a expression than non-HER2-trogocytosed effector cells. In breast cancer patients, HER2 expression on tumor-infiltrated immune cells in treatment naïve HER2+ tumors was associated with a pCR to trastuzumab-based PST. Conclusions: HER2-trogocytosis is visible evidence of tumor microenvironment interaction between cancer cells and immune cells. Given that effective contact between these cells is critical for immune destruction of target cancer cells, this interaction is of great significance. It is possible that HER2 trogocytosis could be used as a predictive biomarker for trastuzumab-based PST efficacy in HER2+ breast

Photoacoustic tomography is a recently developed imaging modality that can provide high spatial-resolution images of hemoglobin distribution in tissues such as the breast. Because breast cancer is an angiogenesis-dependent type of malignancy, we evaluated the clinical acceptability of breast tissue images produced using our first prototype photoacoustic mammography (PAM) system in patients with known cancer. Post-excisionally, histological sections of the tumors were stained immunohistochemically (IHC) for CD31 (an endothelial marker) and carbonic anhydrase IX (CAIX) (a marker of hypoxia). Whole-slide scanning and image analyses were used to evaluate the tumor microvessel distribution pattern and to calculate the total vascular perimeter (TVP)/area for each lesion. In this clinical study, 42 lesions were primarily scanned using PAM preoperatively, three of which were reported to be benign and were excluded from statistical analysis. Images were produced for 29 out of 39 cancers (visibility rate = 74.4%) at the median depth of 26.5 (3.25-51.2) mm. Age, menopausal status, body mass index, history of neoadjuvant treatment, clinical stage and histological tumor angiogenesis markers did not seem to affect the visibility. The oxygen saturation level in all of the measured lesions was lower than in the subcutaneous counterpart vessels (Wilcoxon test, p value<0.001), as well as in the counterpart contralateral normal breast region of interest (ROI) (Wilcoxon test, p value = 0.001). Although the oxygen saturation level was not statistically significant between CAIX-positive vs. -negative cases, lesional TVP/area showed a positive correlation with the oxygen saturation level only in the group that had received therapy before PAM. In conclusion, the vascular and oxygenation data obtained by PAM have great potential for identifying functional features of breast tumors.

The biological significance of STK17A, a serine/threonine kinase, in the liver is not known. We analyzed STK17A expression in HepG2 cells and human liver tissue. Accordingly, we investigated whether STK17A could help in identifying earlier changes during the evolution of chronic rejection (CR) after liver transplantation. RT-PCR and immunofluorescence were used to analyze STK17A expression in HepG2 cells. Antibody microarray was performed using human liver samples from CR and healthy donors. Immunohistochemistry was used to verify the clinical utility of STK17A on sequential biopsies for the subsequent development of CR. A novel short isoform of STK17A was found in HepG2 cells. STK17A was localized in the nuclei and bile canaliculi in HepG2 cells and human livers. Microarray of STK17A revealed its decrease in failed liver allografts by CR. During the evolution of CR, the staining pattern of bile canalicular STK17A gradually changed from diffuse linear to focal intermittent. The focal intermittent staining pattern was observed before the definite diagnosis of CR. In conclusion, the present study was the first to find localization of STK17A in normal bile canaliculi. Abnormal expression and localization of STK17A were associated with CR of liver allografts since the early stage of the rejection process.