Progressive changes in the protein expression profile of alveolar septa in early-stage lung adenocarcinoma.

BACKGROUND: Adenocarcinomas show a stepwise progression from atypical adenomatous hyperplasia (AAH) through adenocarcinoma in situ (AIS) to invasive adenocarcinoma (IA). Immunoglobulin superfamily containing leucine-rich repeat (ISLR) is a marker of tumor-restraining cancer-associated fibroblasts (CAFs), which are distinct from conventional, strongly α-smooth muscle actin (αSMA)-positive CAFs. Fibroblast activation protein (FAP) has been focused on as a potential therapeutic and diagnostic target of CAFs. METHODS: We investigated the changes in protein expression during adenocarcinoma progression in the pre-existing alveolar septa by assessing ISLR, αSMA, and FAP expression in normal lung, AAH, AIS, and IA. Fourteen AAH, seventeen AIS, and twenty IA lesions were identified and randomly sampled. Immunohistochemical analysis was performed to evaluate cancer-associated changes and FAP expression in the pre-existing alveolar structures. RESULTS: Normal alveolar septa expressed ISLR. The ISLR level in the alveolar septa decreased in AAH and AIS tissues when compared with that in normal lung tissue. The αSMA-positive area gradually increased from the adjacent lung tissue (13.3% ± 15%) to AIS (87.7% ± 14%), through AAH (70.2% ± 21%). Moreover, the FAP-positive area gradually increased from AAH (1.69% ± 1.4%) to IA (11.8% ± 7.1%), through AIS (6.11% ± 5.3%). Protein expression changes are a feature of CAFs in the pre-existing alveolar septa that begin in AAH. These changes gradually progressed from AAH to IA through AIS. CONCLUSIONS: FAP-positive fibroblasts may contribute to tumor stroma formation in early-stage lung adenocarcinoma, and this could influence the development of therapeutic strategies targeting FAP-positive CAFs for disrupting extracellular matrix formation.

KDM2B-Rearranged Soft Tissue Sarcomas Expand the Concept of BCOR-Associated Sarcoma.

Sarcomas with BCOR genetic alterations (BCOR-associated sarcomas) represent a recently recognized family of soft tissue and bone tumors characterized by BCOR fusion, BCOR internal tandem duplication, or YWHAE::NUTM2B fusion. Histologically, the tumors demonstrate oval to spindle cell proliferation in a variably vascular stroma and overexpression of BCOR and SATB2. Herein, we describe 3 soft tissue sarcomas with KDM2B fusions that phenotypically and epigenetically match BCOR-associated sarcomas. The cases included 1 infant, 1 adolescent, and 1 older patient. All tumors showed histologic findings indistinguishable from those of BCOR-associated sarcomas and were originally diagnosed as such based on the phenotype. However, none of the tumors had BCOR or YWHAE genetic alterations. Instead, targeted RNA sequencing identified in-frame KDM2B::NUTM2B, KDM2B::CREBBP, and KDM2B::DUX4 fusions. KDM2B fusions were validated using reverse-transcription PCR, Sanger sequencing, and in situ hybridization assays. Genome-wide DNA methylation analysis matched all 3 tumors with BCOR-associated sarcomas using the Deutsches Krebsforschungszentrum (DKFZ) classifier and t-distributed stochastic neighbor embedding analysis. One localized tumor showed a flat genome-wide copy number profile, and the patient remained disease-free after treatment. The other tumors showed multiple copy number alterations, including MDM2/CDK4 amplification and/or CDKN2A/B loss, and both tumors metastasized, leading to the patient's death in one of the cases. When tested using KDM2B immunohistochemistry, all 3 KDM2B-rearranged sarcomas showed diffuse strong staining, and all 13 sarcomas with BCOR genetic alterations also demonstrated diffuse, strong, or weak staining. By contrast, among 72 mimicking tumors, only a subset of synovial sarcomas showed focal or diffuse weak KDM2B expression. In conclusion, our study suggests that KDM2B-rearranged soft tissue sarcomas belong to the BCOR-associated sarcoma family and expand its molecular spectrum. This may be related to the known molecular relationship between KDM2B and BCOR in the polycomb repressive complex 1.1. Immunohistochemical analysis of KDM2B is a potentially valuable diagnostic tool for BCOR-associated sarcomas, including those with KDM2B rearrangement.

Cutaneous syncytial myoepithelioma with folliculocentric growth and EWSR1 gene rearrangement: A case report.

Cutaneous syncytial myoepithelioma is a tumor type that was initially reported in 2013 as a syncytial variant of cutaneous myoepithelioma characterized by intradermal nodular proliferation of oval to spindle-shaped tumor cells in solid and syncytial patterns. Fusion of genes Ewing sarcoma breakpoint region 1 / EWS RNA binding protein 1 (EWSR1) and pre-B cell leukemia homeobox 3 (PBX3) is found in approximately 90% of the cases. We report a case of cutaneous syncytial myoepithelioma with diagnostic difficulty due to folliculocentric morphology and atypical immunohistochemical results, including diffuse positivity of α-smooth muscle actin and claudin 4 and negative immunoreactions for epithelial membrane antigen and S100 protein. In the present case, fluorescence in situ hybridization study demonstrated EWSR1 rearrangement. We further provide a discussion of differential diagnoses with a review of relevant literature.

Nuclear grade and comedo necrosis of ductal carcinoma in situ as histopathological eligible criteria for the Japan Clinical Oncology Group 1505 trial: an interobserver agreement study.

OBJECTIVE: The Japan Clinical Oncology Group 1505 trial is a single-arm multicentre prospective study that examined the possibility of non-surgical follow-up with endocrine therapy for patients with low-grade ductal carcinoma in situ. In that study, the eligible criteria included histopathological findings comprising low to intermediate nuclear grade and absence of comedo necrosis, and cases were entered according to the local histopathological diagnosis. Nuclear grade is largely based on the Consensus Conference criteria (1997), whereas comedo necrosis is judged according to the Rosen's criteria (2017). The purpose of this study was to standardize and examine the interobserver agreement levels of these histopathological criteria amongst the participating pathologists. METHODS: We held slide conferences, where photomicrographs of haematoxylin-eosin-stained slides from 68 patients with ductal carcinoma in situ were presented using PowerPoint. The nuclear grade and comedo necrosis statuses individually judged by the pathologists were analysed using κ statistics. RESULTS: In the first and second sessions, where 22 cases each were presented, the interobserver agreement levels of nuclear grade whether low/intermediate grade or high grade were moderate amongst 29 and 24 participating pathologists, respectively (κ = 0.595 and 0.519, respectively). In the third session where 24 cases were presented, interobserver agreement levels of comedo necrosis or non-comedo necrosis were substantial amongst 25 participating pathologists (κ = 0.753). CONCLUSION: Although the concordance rates in nuclear grade or comedo necrosis were not high in a few of the cases, we believe that these results could provide a rationale for employing the present criteria of nuclear grade and comedo necrosis in the clinical study of ductal carcinoma in situ.

Improvement strategies for successful next-generation sequencing analysis of lung cancer.

Aim: We aimed to improve the success rate of NGS (next-generation sequencing) analysis through improved strategies of lung cancer sampling. Materials & methods: The improvement strategies are as follows. Surgically resected specimens were preferentially submitted in cooperation with pathologists and surgeons. In bronchoscopic samples, the size of the sample collection device and the number of samples collected was increased. Results: The strategies increased the success rate of NGS analysis of DNA from 69.3 to 91.1%, and that of RNA from 64.6 to 90.0%. Discussion: The introduction of strategies aimed at improving the success of NGS analysis resulted in an improvement in the success rate and brought us closer to the delivery of effective precision medicine in cancer therapy.

Pulmonary carcinosarcoma characterized by small round cells with neuroendocrine, myogenic, and chondrogenic differentiation: An extremely rare case.

Carcinosarcoma is a clonal tumor developed through sarcomatoid changes in a carcinoma via the epithelial-mesenchymal transition (EMT). Here, we present an extremely rare case of pulmonary carcinosarcoma characterized by components suggesting pluripotency, namely neuroendocrine, myogenic, and chondrogenic differentiation, based on immunohistochemical analysis. A 42-year-old Japanese man was admitted to our hospital. Analysis of tumor tissue after right upper lobe lobectomy revealed a transition between carcinomatous and sarcomatous components. Immunohistochemical analysis suggested immortality owing to complete loss of p53 and diffuse expression of p16 in both the carcinomatous and sarcomatous components. There were also scattered cell groups expressing aldehyde dehydrogenase 1 family member A1, SOX2, CD133, and c-kit, suggesting the possible presence of cancer stem cells. Our findings in this case suggested that the EMT may play a key role in mediating the immortality of tumor cells in carcinosarcoma and facilitating the pluripotency of cancer stem cells.

Proliferative CD8(+) PD-1(+) T-cell infiltration in a pembrolizumab-induced cutaneous adverse reaction.

Pembrolizumab, a humanized monoclonal immunoglobulin (Ig) G4 antibody that is directed against the human cell surface receptor PD-1, is a PD-1 pathway inhibitor that has been approved to treat various malignant diseases, including advanced non-small cell lung cancer (NSCLC). PD-1 is the major inhibitory receptor regulating T-cell exhaustion, and T-cells with high PD-1 expression lose their ability to eliminate cancer. PD-1 pathway blockade by pembrolizumab reinvigorates exhausted T-cells and restores their antitumor immune responses. However, reinvigorated T-cells also evoke immune-related adverse effects (irAEs), which stem from the restored activity. Currently, the pathogenic mechanisms of irAEs have not been sufficiently determined. We experienced a patient with NSCLC with high PD-L1 expression and cervical lymph node metastases, who demonstrated a good clinical response to first line pembrolizumab but suffered from a severe cutaneous adverse event. Both of his skin lesions and cervical metastases showed extensive CD8(+) PD-1(+) T-cell infiltration in immunofluorescence analysis. This finding suggests a possible contribution of reinvigorated CD8(+) PD-1(+) T-cells in anti-PD-1 therapy-induced skin rash. Intriguingly, CD8(+) T-cells in the skin rash showed higher Ki-67 expression, a proliferation marker, than those in the cervical lymph node lesion. This is the first report of an association between proliferative CD8(+) PD-1(+) T-cells and irAEs.

Pseudomyxoma peritonei of a mature ovarian teratoma caused by mismatch repair deficiency in a patient with Lynch syndrome: a case report.

BACKGROUND: Pseudomyxoma peritonei (PMP) is a rare disease with an estimated incidence of 1-2 cases per million individuals per year. PMP is characterized by the accumulation of abundant mucinous or gelatinous fluid derived from disseminated tumorous cells. Most of the tumorous cells are originated from rupture of appendiceal neoplasms, but some are from the metastasis of cancer of the colon, ovary, fallopian tube, urachus, colorectum, gallbladder, stomach, pancreas, lung and breast. Although frequent mutations in KRAS and/or GNAS genes have been reported, precise molecular mechanism underlying PMP remains to be elucidated. It is of note that mucinous tumour is one of the frequent histological features of colorectal cancer (CRC) in Lynch syndrome (LS), an autosomal dominantly inherited disease caused by a germline mutation of the DNA mismatch repair (MMR) genes including human mutL homolog 1 (MLH1), human mutS homolog 2 (MSH2), human mutS homolog 6 (MSH6), and postmeiotic segregation increased 2 (PMS2). Therefore, typical LS-associated tumours show mismatch repair instability. Although LS patients are most strongly predisposed to CRC, PMPs from mucinous CRC have not been reported in LS patients. CASE PRESENTATION: In this report, we report a case of PMP originating from an ovarian teratoma in a LS patient. The patient had surgical treatment of PMP arising from an ovarian teratoma at the age of 38 years, and later developed a transverse colon cancer at the age of 40. The patient's family history fulfilled the Amsterdam criteria, and genetic analysis of the peripheral leukocytes identified a germ line mutation in the MLH1 gene (MLH1 c.1546dupC p.Q516PfsX3). Interestingly, immunohistochemical staining showed that the expression of MLH1 was lost in the colon cancer as well as the ovarian teratoma. Consistent with the loss of MLH1 expression, both tumours showed high microsatellite instability (MSI-H). CONCLUSION: This case suggested that LS patients may develop various types of tumours including ovarian PMP, and that mismatch repair deficiency may play a role in the development of PMP derived from, at least, a part of ovarian teratomas.

KMT2A-rearranged sarcoma with unusual fusion gene CBX6::KMT2A::PYGO1.

Recently, rare sarcomas harboring KMT2A rearrangements have been reported. They occur in relatively young individuals, exhibit a sclerosing epithelioid fibrosarcoma-like morphology, and often have an aggressive prognosis. YAP1::KMT2A::YAP1 is the most common fusion gene, followed by VIM::KMT2A. We report the case of a 47-year-old man with a spindle cell tumor arising from the subcutaneous tissue of the right anterior chest. The tumor harbored an unusual novel fusion gene, CBX6::KMT2A::PYGO1. Histologically, the tumor consisted of proliferating spindle-shaped cells with uniform nuclei, which varied in cell density and the amount of intervening collagen fibers. After 2 years and 8 months without postoperative treatment, the patient showed no recurrence or metastasis. Although highly likely irreproducible, tumors with the CBX6::KMT2A::PYGO1 fusion gene were morphologically somewhat different from those containing the YAP1::KMT2A::YAP1. This suggests that KMT2A rearrangements with fusion gene partners different from YAP1 result in purely spindle-shaped cell tumors that produce collagen fibers.

Genetic dissection of intratumor heterogeneity of PD-L1 expression in EGFR-mutated lung adenocarcinoma.

In this study, we investigated the association between PD-L1 expression in tumor cells and underlying genetic mutations, which was analyzed in detail using laser microdissection and next-generation sequencing analysis. To investigate whether driver mutations are involved in the background of PD-L1 expression, the EGFR major activating mutation was selected as the most frequent driver mutation. Surgical resection specimens were used to extract sufficient amounts of nucleic acids for analysis, and the high tumor proportion score (TPS:100%) and low (TPS: 0%) PD-L1-expressing parts of the tumor were each laser microdissected to examine the association between PD-L1 expression heterogeneity and genetic mutations within the same tumor. The association between PD-L1 heterogeneity and gene mutations within the same tumor was investigated. Analysis showed no association between PD-L1 expression heterogeneity and genetic variants, which were found to be almost identical. However, PD-L1 expression was found to be associated with the number of tumor infiltrating lymphocytes (TILs) present in the tumor, which may be related to whether or not lymphocytes can infiltrate into the tumor depending on the tumor histological type (solid pattern, lepidic pattern, etc.) and other factors.

Secondary leiomyosarcoma of the nasal cavity in a treated patient with possible hereditary retinoblastoma with germline reciprocal translocation of RB1 and DMXL1 and somatic TP53 mutation: A case report.

Retinoblastoma is a common primary intraocular malignant tumor that affects infants and young children. Radiation therapy for hereditary retinoblastoma increases the risk of secondary malignancy. The present report discusses the case of a retinoblastoma survivor who developed secondary leiomyosarcoma 42 years after receiving radiation therapy. The retinoblastoma of the patient was unilateral, and the patient had no family history of the disease. RNA and DNA panel sequencing of the leiomyosarcoma tissue was performed to elucidate the molecular mechanism of this secondary malignancy. The RNA panel sequencing detected a germline reciprocal translocation of RB1 and DMXL1, leading to a diagnosis of possible hereditary retinoblastoma. Furthermore, it detected a somatic fusion gene (RAD51-KNL1). The DNA panel sequencing identified various germline or somatic variants, including a somatic splice acceptor site mutation of TP53. We hypothesized that the molecular mechanism of the secondary malignancy of this patient was the combination of a germline reciprocal translocation of RB1 and DMXL1 and the accumulation of various somatic mutations containing the splice acceptor site mutation of TP53, which ultimately led to the development of a secondary leiomyosarcoma. Further prospective investigations are necessary to fully understand the role of reciprocal translocation of RB1 and DMXL1 or other mutations in the tumorigenesis of second malignancies in patients with hereditary retinoblastoma.

Analytical Performance of a Highly Sensitive System to Detect Gene Variants Using Next-Generation Sequencing for Lung Cancer Companion Diagnostics.

The recent increase in the number of molecular targeted agents for lung cancer has led to the demand for the simultaneous testing of multiple genes. Although gene panels using next-generation sequencing (NGS) are ideal, conventional panels require a high tumor content, and biopsy samples often do not meet this requirement. We developed a new NGS panel, called compact panel, characterized by high sensitivity, with detection limits for mutations of 0.14%, 0.20%, 0.48%, 0.24%, and 0.20% for EGFR exon 19 deletion, L858R, T790M, BRAF V600E, and KRAS G12C, respectively. Mutation detection also had a high quantitative ability, with correlation coefficients ranging from 0.966 to 0.992. The threshold for fusion detection was 1%. The panel exhibited good concordance with the approved tests. The identity rates were as follows: EGFR positive, 100% (95% confidence interval, 95.5-100); EGFR negative, 90.9 (82.2-96.3); BRAF positive, 100 (59.0-100); BRAF negative, 100 (94.9-100); KRAS G12C positive, 100 (92.7-100); KRAS G12C negative, 100 (93.0-100); ALK positive, 96.7 (83.8-99.9); ALK negative, 98.4 (97.2-99.2); ROS1 positive, 100 (66.4-100); ROS1 negative, 99.0 (94.6-100); MET positive, 98.0 (89.0-99.9); MET negative 100 (92.8-100); RET positive, 93.8 (69.8-100); RET negative, 100 (94.9-100). The analytical performance showed that the panel could handle various types of biopsy samples obtained by routine clinical practice without requiring strict pathological monitoring, as in the case of conventional NGS panels.

Primary Epithelioid Rhabdomyosarcoma of the Liver: Case Report of an Unusual Histological Variant.

Rhabdomyosarcoma (RMS) is a soft tissue tumor with striated muscle cell differentiation. It mostly occurs in children. While it can affect any part of the body, it commonly involves the urogenital organs, head and neck including the parameninges and orbit, and limbs. We describe an adult case of primary epithelioid RMS of the liver. A 71-year-old man presented with a 5.6 cm liver mass. Tumor histology revealed diffuse proliferation of small epithelioid cells and focal spindle cells. The tumor cells were immunohistochemically positive for myogenin (positive ratio 30%), desmin, Myo D1, and CD56. The tumor weakly expressed MDM2 and did not express CDK4. This suggested that dedifferentiated liposarcoma with a rhabdomyosarcomatous component was unlikely. There was no fusion gene of PAX3-FKHR or PAX7- FKHR to indicate alveolar RMS by RT-PCR. Subsequently, RNA Pan-Cancer Targeted sequencing was performed for 1385 genes revealed a single base substitution (c.742C>T) in TP53 that changes an amino acid (p.Arg248Trp). No fusion gene was found. No other primary RMS lesions were detected aside from the liver lesion. The tumor was diagnosed as a primary epithelioid RMS of the liver. His RMS already metastasized to the lymph nodes of the entire body. The patient declined further therapy and died one year later. This was the first case report of a primary epithelioid RMS of the liver.

A novel EWSR1-HOXB13 rearrangement in a fibroblastic tumor from the abdomen of a young woman.

We describe a novel EWSR1-HOXB13-fusion in a fibroblastic tumor from the abdominal wall of a 29-year-old woman. This tumor caused intermittent intense pain and had grown to approximately 5 cm in size over two years. The tumor was located beneath subfascial section of the abdominal wall and was invading the abdominal cavity and pressing on the liver. The tumor was well-circumscribed and consisted of intersected fascicles of monomorphic spindle-shaped cells with uniform ovoid nuclei lacking nuclear pleomorphism or mitotic activity. This tumor was immunohistochemically negative for pan-cytokeratin AE1/AE3, desmin, SMA, S100, myogenin, MyoD1, CD34, melanosome, SOX10, STAT6, SS18-SSX, and ERG. H3K27me3 was retained. RNA sequencing revealed a unique EWSR1-HOXB13-fusion, and strong, diffuse nuclear immunostaining for HOXB13 was observed. No local recurrence or evident distant metastasis were observed over eight months without chemotherapy, implying that the behavior of this tumor is not yet known.