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Accurate diagnosis of the localization of prostate cancer (PCa) on magnetic resonance imaging (MRI) remains a challenge. We aimed to assess discrepancy between the location of PCa pathologically diagnosed using surgical specimens and lesions indicated as possible PCa by the Prostate Imaging Reporting and Data System on MRI. The primary endpoint was the concordance rate between the site of probable clinically significant PCa (csPCa) identified using biparametric MRI (bpMRI) and location of PCa in the surgical specimen obtained using robot-assisted total prostatectomy. Among 85 lesions identified in 30 patients; 42 (49.4%) were identified as possible PCa on MRI. The 85 PCa lesions were divided into positive and negative groups based on the bpMRI results. None of the patients had missed csPCa. Although the diagnostic accuracy of bpMRI was relatively high for PCas located in the middle of the prostate (p = 0.029), it was relatively low for PCa located at the base of the prostate, all of which were csPCas. Although current modalities can accurately diagnose PCa, the possibility that PCa is present with multiple lesions in the prostate should be considered, even if MRI does not detect PCa.

Abstract Background Triple‐negative breast cancer (TNBC) is characterized by the loss of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2. The aggressive clinicopathological features and resistance to currently available therapeutics of the disease warrant an urgent need for the development of novel alternate therapeutic options. We have previously reported adiponectin‐expressing regulatory T cells (A‐Tregs), which can induce apoptosis in TNBC through the cell‐in‐cell phenomenon. In this study, we aimed to elucidate the molecule that allows TNBC cells to engulf A‐Tregs. Methods A monoclonal antibody, which repressed the engulfment of A‐Tregs by TNBC cells, was developed. Immunoprecipitation followed by mass spectrometry and small interfering RNAs‐mediated gene silencing was performed to characterize the antigen. Results We successfully generated a monoclonal antibody, designated G1D7, which abrogated the engulfment of A‐Tregs by TNBC and subsequent A‐Treg‐mediated apoptosis. G1D7 detected the immunoglobulin‐like type I membrane protein IZUMO2, a molecule related to IZUMO1 that is essential for cell–cell membrane binding and fusion of sperm to oocyte. Conclusion The findings highlight the importance of IZUMO2 on TNBC cells in facilitating the cell‐in‐cell phenomenon by A‐Tregs.

Abstract Background In our previous study, we identified a population of adiponectin expressing regulatory T cells (Tregs) residing within thymic nurse cell complexes, which were capable of inhibiting the development of breast cancer in vitro. Triple‐negative breast cancer (TNBC) with no proper treatment at present is characterized by the absence of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor‐2. In this study, we aimed to investigate the potential of a cultured T cell fraction comprising adiponectin‐expressing Tregs, referred to as A‐TregTF (adiponectin‐expressing Treg‐containing T cell fraction), in inhibiting the progression of TNBC in vivo. Methods The efficacy of a spontaneously expanding T cell fraction comprising adiponectin‐expressing Treg in inhibiting tumor growth was analyzed in a murine orthotopic 4 T1‐Luc TNBC model. Results The treatment with T cell fraction containing adiponectin‐expressing Tregs significantly inhibited the growth and metastasis of orthotopically transplanted 4 T1‐Luc tumor cells. Histopathological examination further revealed that the adiponectin‐expressing Tregs infiltrated the tumor tissue via a cell‐in‐cell mechanism and were found to be specifically localized around the necrotic areas. Conclusions Based on our findings, the T cell fraction comprising adiponectin‐expressing Tregs, represents a potential candidate for adoptive cell therapy against TNBC.

Abstract Background A population of regulatory T cells (Treg), which reside within thymic nurse cell complexes, express adiponectin and abrogate breast cancer development in transgenic mice. In this study, we examined whether adiponectin‐expressing Treg could impair triple‐negative breast cancer, which is defined by a lack of estrogen receptors, progesterone receptors, and human epidermal growth factor receptor‐2. Methods CD4‐ and CD25‐positive cells were sorted from cultured T lymphocytes of a previously characterized experimental thymic tumor model composed of thymic nurse cells and abundant lymphoid stroma. These sorted cells were examined for FOXP3 and adiponectin immunoreactivity and subsequently exposed to triple‐negative breast cancer MDA‐MB‐157 and ‐231 cells. Results Adiponectin‐expressing Treg were obtained by CD4‐ and CD25‐positive sorting and cell death was induced in triple‐negative breast cancer cells through the cell‐in‐cell phenomenon. Conclusions Adiponectin‐expressing Treg may be candidates for adoptive cell therapy against triple‐negative breast cancer.

Abstract Background Late recurrence of gastric cancer at 10 years post-gastrectomy is extremely rare, and the underlying mechanism remains unclear. We report a para-aortic lymph node metastasis case that recurred 12 years postoperatively. Case presentation A 44-year-old woman pathologically diagnosed with moderately to poorly differentiated adenocarcinoma with pT2(SS)pN2cM0pStageIIIA according to the Japanese Classification of Gastric Carcinoma (the 13th Edition) underwent laparoscopic distal gastrectomy with D1 + lymph node dissection. She received adjuvant chemotherapy with tegafur-uracil (400 mg/day) for 2 years. At postoperative year (POY) 5, a swollen lymph node was detected in the No.16b1lat lymph node station. However, positron emission tomography (PET) revealed normal uptake, and the levels of tumor markers were within normal limits; hence, the possibility of metastasis was considered low, and the patient was placed under observation. At POY 12, computed tomography revealed an enlargement of the No.16b1lat lymph node station, and PET showed abnormal uptake. Endoscopic ultrasound-guided fine-needle aspiration revealed a moderately differentiated adenocarcinoma. Hence, a diagnosis of recurrence of gastric cancer was made. The patient underwent para-aortic nodal dissection (PAND) of No.16b1lat & int stations. Immunochemical staining results also suggested the recurrence of gastric cancer. However, the expression of CD44 variant 9 (CD44v9), a cancer stem cell marker for gastric adenocarcinoma, was attenuated in the recurrent lesions compared with that in the primary lesions. Postoperatively, she received chemotherapy with tegafur–gimeracil–oteracil (80 mg/day) for 1 year. Bone metastasis was observed at POY 4 after PAND, and the IHC analysis showed a HER2 score of 3 + in a needle biopsy specimen of bone metastasis. The expression of CD44v9 was slightly positive. The patient is being treated with chemotherapy with FOLFOX + trastuzumab. Conclusions A defense mechanism against reactive oxygen species has been reported as a mechanism causing recurrence of CD44v9-positive gastric cancer. Consequently, CD44v9-positive gastric cancer grows in metastatic organs, repeatedly self-renews, and proliferates to form recurrent lesions. In the present case, the degree of CD44v9 staining in recurrent lesions was suggested to be related to the recurrence time.

Abstract Background Micronodular thymic neoplasm with lymphoid stroma (MNT), a subtype of thymic tumor, is histopathologically characterized by micronodular thymic epithelial cell nests with lymphoid stroma. Despite the distinct histopathology of MNT, its pathogenesis remains unclear. Methods In this study, we aimed to examine a thymic tumor harboring thymic epithelial and lymphoid cells in a nonobese diabetic/severe combined immunodeficiency mouse. Results The excised tumor cells were cultured in vitro and comprised epithelial tumor cells and lymphoid cells. During a three‐dimensional cell culture, the epithelial tumor cells formed micronodular cell nests surrounded by lymphoid stroma. Notably, the lymphoid cells underwent apoptosis when they were separated from the epithelial tumor cells. Cutaneous transplantation of the cultured epithelial cells with splenocytes from BALB/c mice led to tumor formation, and these cells demonstrated a histopathology similar to that of human MNT in a nonobese diabetic/severe combined immunodeficiency mouse. Conclusion Given its overlapping features with human MNT, the transplanted tumor could serve as an experimental model of this disease.

Malignant pleural mesothelioma (MPM) develops primarily from asbestos exposures and has a poor prognosis. In this study, The Cancer Genome Atlas was used to perform a comprehensive survival analysis, which identified the CHST4 gene as a potential predictor of favorable overall survival for patients with MPM. An enrichment analysis of favorable prognostic genes, including CHST4, showed immune-related ontological terms, whereas an analysis of unfavorable prognostic genes indicated cell-cycle-related terms. CHST4 mRNA expression in MPM was significantly correlated with Bindea immune-gene signatures. To validate the relationship between CHST4 expression and prognosis, we performed an immunohistochemical analysis of CHST4 protein expression in 23 surgical specimens from surgically treated patients with MPM who achieved macroscopic complete resection. The score calculated from the proportion and intensity staining was used to compare the intensity of CHST4 gene expression, which showed that CHST4 expression was stronger in patients with a better postoperative prognosis. The median overall postoperative survival was 107.8 months in the high-expression-score group and 38.0 months in the low-score group (p = 0.044, log-rank test). Survival after recurrence was also significantly improved by CHST4 expression. These results suggest that CHST4 is useful as a prognostic biomarker in MPM.

Abstract Background As mesothelioma generally has an unfavorable prognosis, further advances are needed to improve the outcomes in patients with mesothelioma. In the present study, we generated and characterized a monoclonal antibody that could inhibit mesothelioma cell proliferation in a xenotransplantation mouse model. Methods We generated monoclonal antibodies by immunizing mice with cultured mesothelioma cells. These antibodies were then characterized by immunofluorescence staining, immunohistochemical staining, secondary antibody‐drug conjugate assay, antibody inoculation in a xenotransplantation mesothelioma mouse model, and mass spectrometry followed by small interfering RNA (siRNA) analysis. 5' rapid amplification of complementary DNA ends followed by sequencing was performed to deduce the amino acid sequences of the variable regions of the light and heavy chains of AX10. Results An IgG2b κ‐type AX10 antibody against the cell surface membrane of sarcomatoid mesothelioma cells was generated. AX10 immunoreactivity was detected in 12 out of 22 different mesothelioma tissue specimens, but there was little AX10 immunoreactivity in a normal human tissue array. AX10 decreased Matrigel invasion by MPM‐1 cells but did not affect cell proliferation. Notably, AX10 significantly inhibited the proliferation of MPM‐1 cells xenotransplanted into Severe combined immunodeficiency‐Nonobese diabetic mice. Matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry followed by siRNA silencing indicated that AX10 reacted to a unique alternatively spliced isoform of sarcolemma‐associated protein. AX10 is composed of as yet unregistered amino acid sequences in its variable region. Conclusions AX10 could have therapeutic potential for patients with sarcomatoid mesothelioma.

Abstract Background Gastric carcinosarcoma is most frequently diagnosed at an advanced stage when the tumor is generally large with invasion into other organs, lymph node metastasis, and distant metastasis. Standard chemotherapy has not been established, and surgery is the only curative treatment. Here, we present a case of postoperative recurrence of gastric carcinosarcoma under long-term tumor control with pazopanib. Case presentation A 77-year-old man was referred to our hospital because of nausea and vomiting. Computed tomography and upper gastrointestinal endoscopy revealed a type 1 tumor arising from the gastric antrum and extending into the duodenal bulb. He underwent distal gastrectomy (D2) with Roux-en-Y reconstruction. Histopathologically, the tumor had mixed adenocarcinoma and sarcoma components. According to the tumor–node–metastasis classification, the diagnosis was primary gastric carcinosarcoma pT1bN1M0 stage IB. Liver metastasis was detected 2 months after surgery; multiple lung metastases were detected 17 month after surgery. A genomic profiling test was performed using liver specimens as the patient became refractory to chemotherapy commonly used for gastric cancer, and the test revealed FGFR2 amplification along with TP53 R209*, AKT3 N127D, NOTCH1 A2036T, and POLD1 M161I. The patient was treated with pazopanib (800 mg/daily), and the tumor growth was controlled for 11 months. Conclusions We report a case of postoperative recurrence of gastric carcinosarcoma under long-term tumor control with pazopanib. This case suggested that pazopanib may be effective in treating gastric carcinosarcoma.

Three cases of primary thymic neuroendocrine tumors resembling a vascular neoplasm were reported as “Angiomatoid neuroendocrine carcinoma of the thymus.” Recently, we encountered another case of a thymic neuroendocrine cell tumor that grossly mimicked a vascular neoplasm. A man in his early 60 s, who presented with right thoracic pain, was admitted to our hospital. He had a 45 × 35 mm vascular-rich tumor in the thymus and underwent total thymectomy. Histopathological examination revealed that the tumor was composed of many blood‑filled caverns lined with stratified conventional neuroendocrine tumor cells expressing insulinoma-associated protein 1 and synaptophysin immunoreactivity. Notably, the blood-filled caverns were not lined with CD31-positive endothelial cells, as previously reported. By contrast, the caverns were focally lined with cells expressing SRY-Box Transcription Factor 17, which is well characterized to drive the conversion of fibroblast progenitor cells to endothelial cells by its transcriptional property. However, SRY-Box Transcription Factor 17 immunoreactivity was not restricted to the nucleus in blood-filled caverns and was also detected in the nucleus of endothelial cells in tumor vessels in the canonical carcinoid area. Dismaturation of endothelial cells might participate in the angiomatoid features of thymic neuroendocrine cell tumors.

Esophageal cancer rarely grows as an intramural tumor with an intact surface epithelium. A previous report described submucosal tumor-like esophageal cancer that had an overlapping morphological phenotype similar to that of a cutaneous sweat gland tumor. Here, we encountered another case of submucosal esophageal cancer mimicking skin adnexal carcinoma. A man in his early 60s who presented with difficulty in swallowing was admitted to our hospital. He had a 30 × 30 mm submucosal tumor in the abdominal esophagus and underwent partial esophagogastrectomy. Histopathological examination revealed that the tumor was composed of cord-like squamoid cell nests that was partially accompanied by gland structure in the inner layer, as found in cutaneous squamoid ductal eccrine carcinoma. The tumor exhibited CK7 immunoreactivity as did the neighboring dilated ducts of the esophageal gland. We describe a unique submucosal tumor-like esophageal cancer that had overlapping morphological features with squamoid ductal eccrine carcinoma and putatively originated in the esophageal submucosal gland ducts.

Background: Decision-making and selection of treatment modalities for newly diagnosed prostate cancer (PCa) are often determined by risk stratification using grade group (GG), prostate-specific antigen (PSA), and clinical stage. The discrepancies between needle biopsy (NB) and radical prostatectomy (RP) specimens often occur because of the sampling errors in NB or multifocal features of PCa. Thus, we aimed to estimate the preoperative clinical factors for predicting GG upgrading after robot-assisted RP (RARP). Methods: In this retrospective study, we reviewed the clinical and pathological records of patients who underwent RARP at Gifu University Hospital. We focused on patients with organ-confined PCa who had not received neoadjuvant therapy prior to RARP. The primary endpoint was identified as the predictive factor of GG upgrading for RARP specimens compared to those of NB specimens. Results: Eighty-one patients were included in this study. The enrolled patients were divided into two groups: those who had GG upgrading for RARP specimens (the NB upgrade group) or those who did not have GG upgrading (the no upgrade group). The median age of all patients was 70 years, and the median body mass index (BMI) was 22.9 kg/m2. The median neutrophil count was 3720/μL, lymphocyte count was 1543/μL, and neutrophil-to-lymphocyte ratio (NLR) was 2.24. In univariate analysis, BMI, PSA, neutrophil count, and NLR were significantly associated with GG upgrading in RARP specimens compared to NB specimens. BMI and NLR were identified as strong predictive factors for GG upgrading in RARP specimens in the multivariate analysis. Conclusions: Although this study’s small number of enrolled patients was a vital weakness, BMI and NLR might have been significantly correlated with GG upgrading for RP specimens compared with NB specimens. Therefore, BMI and NLR may have potential benefits for newly diagnosed patients with PCa in terms of decision-making and the selection of treatment modalities.

Approximately 24 cases of cytokeratin-positive interstitial reticulum cell tumors have been reported in English literature. In this paper, we report a case of cytokeratin-positive interstitial reticulum cell tumor that was localized in the parafollicular region of the axillary lymph node and was an incidental finding in a patient with breast cancer. A 50 year-old woman underwent a mastectomy and lymph node dissection following a preoperative diagnosis of bilateral breast cancer. Histopathological examination revealed that the patient had non-invasive and invasive ductal carcinoma in the right and left mammary glands. Although we could not detect breast cancer metastasis in the lymph nodes, one of eight right axillary lymph nodes harbored an 11 × 8 mm discohesive sheet of large polygonal epithelioid tumor cells in the parafollicular area. Tumor cells were immunoreactive for AE1/AE3, CAM5.2, CK18 and l-caldesmon and negative for CD1a, CD21, CD23, CD31, CD68, and S‑100 protein markers. Based on these findings, the lesion was diagnosed as a cytokeratin-positive interstitial reticulum cell tumor of the lymph node. Notably, this early-stage cytokeratin-positive interstitial reticulum cell tumor demonstrated focal nuclear YAP/TAZ proto-oncogene products, which were recently identified as critical for differentiation, maturation, and function of fibroblastic reticular cells. To the best of our knowledge, this is the first report to describe nuclear YAP/TAZ immunoreactivity in cytokeratin-positive interstitial reticulum cell tumors.

Ovarian tumors include neoplasms derived from somatic cells and germ cells, including teratoma. Sometimes, tumors of the somatic cell type may develop from teratoma, causing diagnostic perturbation. We experienced a case of a tumor composed of several types of tissue in the ovary with a teratoma. When findings of teratoma and somatic tumor coexist in an ovary, it is difficult to differentiate whether a somatic tumor was mixed with a teratoma or a teratoma unitarily caused transformation to a somatic cell tumor. A 72-year-old Japanese woman (gravida, 3; para, 1) presented to our hospital with severe constipation and frequent urination, and a large intrapelvic tumor was detected by computed tomography (CT). Soon after admission, ultrasonography (US) and magnetic resonance imaging (MRI) revealed a large multilocular cystic tumor on her left ovary. Based on the clinical diagnosis of ovarian cancer, she underwent a left ovariectomy, appendectomy, and partial omentectomy. We observed an ovarian tumor consisting of teratoma, primitive neuroectodermal tumor (PNET), adenocarcinoma, various types of sarcomas, and clear cell carcinoma on the H and E-stained sections. The component of clear cell carcinoma showed a nuclear positive reaction against PAX8 and napsin A, as well as a loss of ARID1A, suggesting typical endometriosis-derived clear cell carcinoma. On the other hand, the expression of ARID1A was maintained in teratoma, PNET, non-specific adenocarcinoma, and various types of sarcomas, suggesting that these tumors had an origin different from that of clear cell carcinoma. These findings indicated that the ovarian tumor of this patient contained a clear cell carcinoma derived from a somatic cell and a teratoma that transformed to a wide variety of somatic cell types of tumors, which coexisted on one ovary. The appropriate use of immunohistochemistry was diagnostically effective in this case.