Heart Neoplasms/genetics* ; Hemangiosarcoma/genetics* ; Humans ; Mediastinal Neoplasms ; Thymus Neoplasms

BACKGROUND: Thymic carcinomas (TCs) and thymic neuroendocrine neoplasms (TNENs) are two aggressive subtypes of thymic malignancy. Traditional therapy for advanced TCs and TNENs has limited outcome. New genomic profiling of TCs and TNENs might provide insights that contribute to the development of new treatment approaches. METHODS: We used gene panel sequencing technologies to investigate the genetic aberrations of 32 TC patients and 15 TNEN patients who underwent surgery at Shanghai Chest Hospital between 2015 and 2017. Patient samples were sequenced using a 324-gene platform with licensed technologies. In this study, we focused on clinically relevant genomic alterations (CRGAs), which are previously proven to be pathogenic alterations, to identify the pathology-specific mutational patterns, prognostic signatures of TCs and TNENs. RESULTS: The mutational profiles between TCs and TNENs were diverse. The genetic alterations that ranked highest in TCs were in CDKN2A, TP53, ASXL1, CDKN2B, PIK3C2G, PTCH1, and ROS1 , while those in TNENs were in MEN1, MLL2, APC, RB1 , and TSC2 . Prognostic analysis showed that mutations of ROS1, CDKN2A, CDKN2B, BRAF, and BAP1 were significantly associated with worse outcomes in TC patients, and that mutation of ERBB2 indicated shortened disease-free survival (DFS) and overall survival (OS) in TNEN patients. Further investigation found that the prognosis-related genes were focused on signal pathways of cell cycle control, chromatin remodeling/DNA methylation, phosphoinositide 3-kinases (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR), and receptor tyrosine kinase (RTK)/RAS/mitogen-activated protein kinase (MAPK) signaling. CONCLUSION We profiled the mutational features of 47 Chinese patients with thymic malignancy of diverse pathologic phenotypes to uncover the integrated genomic landscape of these rare tumors, and identified the pathology-specific mutational patterns, prognostic signatures, and potential therapeutic targets for TCs and TNENs.
Humans ; Thymoma ; Protein-Tyrosine Kinases/genetics* ; Proto-Oncogene Proteins/genetics* ; China ; Thymus Neoplasms/pathology* ; Prognosis ; Neuroendocrine Tumors/pathology* ; Mutation/genetics*

Objective: To investigate the clinicopathological features, and molecular genetic alterations of metaplastic thymoma (MT). Methods: A total of ten MT cases, diagnosed from 2011 to 2021, were selected from the Department of Pathology of Jinling Hospital, Nanjing University Medical School, Nanjing, China for clinicopathological and immunohistochemical (IHC) examination and clinical follow-up. Fluorescence in situ hybridization (FISH), next-generation sequencing (NGS), and YAP1 C-terminus (YAP1-CT) IHC were performed to detect YAP1::MAML2 fusions. Results: There were four males and six females, ranging in age from 29 to 60 years (mean 50 years, median 54 years). Microscopically, all tumors showed a typical biphasic morphology consisting of epithelial components and gradually or abruptly transitioning spindle cell components. The two components were present in varying proportions in different cases. Immunophenotypically, the epithelial cells were diffusely positive for CKpan, CK5/6 and p63. The spindle cells were diffusely positive for vimentin and focally positive for EMA. TdT was negative in the background lymphocytes. Ki-67 proliferation index was less than 5%. YAP1 and MAML2 break-apart FISH analyses showed that all ten cases had narrow split signals with a distance of nearly 2 signal diameters and may be considered false-negative. Using YAP1::MAML2 fusion FISH assays, abnormal fusion signals were observed in all the ten cases. NGS demonstrated YAP1::MAML2 fusions in all eight cases with adequate nucleic acids; in two cases the fusions were detected by DNA sequencing and in eight cases by RNA sequencing. All ten cases of MT demonstrated loss of YAP1 C-terminal expression in epithelioid cells. Conclusions: MT is a rare and low-grade thymic tumor characterized by a biphasic pattern and YAP1::MAML2 fusions. Break-apart FISH assays may sometimes show false-negative results due to the proximity of YAP1 and MAML2, while YAP1 C-terminal IHC is a highly sensitive and specific marker for MT. Loss of YAP1 C-terminal expression can also be used to screen YAP1::MAML2 fusions for possible MT cases.
Male ; Female ; Humans ; Adult ; Middle Aged ; Thymoma/genetics* ; In Situ Hybridization, Fluorescence ; Transcription Factors/genetics* ; Mutation ; Thymus Neoplasms/genetics*

Myasthenia gravis is an autoimmune disease that results from an antibody-mediated reaction and occurs with thymoma in 15+ACU- of patients. It is very rarely associated with autoimmune hepatitis. Four cases of myasthenia gravis with autoimmune hepatitis have been reported in the world. We recently experienced a case of 30-year-old man with myasthenia gravis associated with thymoma and autoimmune hepatitis. This condition is the first case that has not been reported previously in Korea. We report this rare condition along with a brief review of the literature.
Adult ; Case Report ; HLA-DR Antigens/genetics ; Hepatitis, Autoimmune/etiology+ACo- ; Human ; Male ; Myasthenia Gravis/complications+ACo- ; Thymoma/etiology+ACo- ; Thymus Neoplasms/etiology+ACo-

ACTH Syndrome, Ectopic ; etiology ; Adult ; Carcinoid Tumor ; pathology ; secretion ; Cushing Syndrome ; etiology ; Humans ; Male ; Pro-Opiomelanocortin ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Thymus Neoplasms ; pathology ; secretion

Germ-line mutations in BRCA2 predispose to early-onset cancer. Homozygous mutant mouse, which has Brca2 truncated in exon 11 exhibit paradoxic occurrence of growth retardation and development of thymic lymphomas. However, due to its large embryonic lethality, cohort studies on the thymic lymphomas were not feasible. With the aid of Cre-loxP system, we demonstrate here that thymus-specific disruption of Brca2 allele without crossing it to p53-mutant background leads to the development of thymic lymphomas. Varying from 16 weeks to 66 weeks after birth, 25% of mice disrupted of Brca2 in the thymus died of thymic lymphomas, whereas previous report did not observe lymphomagenesis using similar Cre-loxP system. Future analysis of thymic lymphomas from these mice presented here will provide information on the cooperative mutations that are required for the BRCA2-associated pathogenesis of cancer.
Animals ; BRCA2 Protein/deficiency/*genetics ; CD4-CD8 Ratio ; Cell Separation ; Flow Cytometry ; Integrases/*genetics/immunology ; Lymphoma/*genetics/immunology/metabolism/pathology ; Mice ; Mice, Knockout ; Organ Specificity ; *Sequence Deletion ; T-Lymphocytes/enzymology/*immunology ; Thymus Gland/immunology/metabolism/pathology ; Thymus Neoplasms/*genetics/immunology/metabolism/pathology ; Tumor Suppressor Protein p53/deficiency/genetics/immunology

OBJECTIVETo study the correlation between amplification of chromosome 1 and histological typing and clinical staging of thymic epithelial tumors according to the WHO classification.

METHODSAmplification of chromosome 1 was detected by interphase fluorescence in-situ hybridization (FISH) in 60 cases of thymic epithelial tumors, including type A thymoma (2 cases), type AB (19 cases), B1 (4 cases), B2 (14 cases), B3 (11 cases), metaplastic thymoma (2 cases), and thymic carcinoma (8 cases) and 11 samples of normal thymus.

RESULTSGain on chromosome 1 was found in 19 cases (31.7%) of thymic epithelial tumors, and none was detected in normal thymic tissues (P < 0.05). The positive rates of gain on chromosome 1 were statistically different among various histological subtypes of thymic epithelial tumors (P < 0.05), in which the highest rate of detection was in thymic carcinoma (6/8), the second, type B3 (6/11), followed by type A (1/2), type AB (4/19), type B2 (2/14) and type B1 (0). The positive rate of gain on chromosome 1 in type B3 had no statistical difference from thymic carcinoma (P > 0.05), but significantly higher than that in other types of thymoma (P < 0.05). In addition, the polysomy rate of chromosome 1 was significantly different among the thymic epithelial tumors at different clinical stages (P = 0.023), and that at stages III and IV was statistically higher than that in stages I and II (P = 0.003) but there was no significant difference between stage I and stage II tumors (P = 0.750).

CONCLUSIONSGain on chromosome 1 is more common in thymic carcinoma and type B3 thymoma than that in other subtypes of thymic epithelial tumors. Thymoma of type B3 may have different genetic features from other subtypes. Detection of gain on chromosome 1 by FISH is helpful in the differential diagnosis and prediction of prognosis in patients with thymic epithelium tumors.

Adult ; Aged ; Carcinoma, Squamous Cell ; genetics ; pathology ; Chromosomes, Human, Pair 1 ; genetics ; Female ; Follow-Up Studies ; Gene Amplification ; Humans ; Male ; Middle Aged ; Neoplasm Staging ; Polyploidy ; Prognosis ; Thymoma ; classification ; genetics ; pathology ; Thymus Neoplasms ; classification ; genetics ; pathology

OBJECTIVETo study the relationship between activation of pro-MMP-2 and expression of matrix metalloproteinases (MMP)-2, MT1-MMP and tissue inhibitor of metalloproteinases (TIMP)-2 mRNA in thymoma and thymic carcinoma; and to study the molecular mechanism of invasion and metastasis of thymic epithelial tumors.

METHODSFresh tissue specimens of thymoma, thymic carcinoma and normal thymus were included. The mRNA expression of MMP-2, MT1-MMP and TIMP-2 were analyzed by real-time reverse transcription polymerase chain reaction. The pro-MMP-2 activation ratio and its localization were determined by gelatin zymography and film in-situ gelatin-Zymography, respectively. Correlation of mRNA expression of MMP-2, MT1-MMP and TIMP-2 was investigated in tumors with different histological subtypes and clinical stages.

RESULTSThere were no significant differences in the expressions of MMP-2, MT1-MMP and TIMP-2 mRNA between I and II stage or III and IV stage thymomas (P > 0.05). However, significant differences of the expressions were observed between three tumor groups: I-II stage, III-IV stage and thymic carcinomas (P < 0.005), and between three histological subtypes: AB-B1 (lymphocyte-rich and mixed types), B2-B3 (cortical and predominantly polygonal cells types) and thymic carcinomas (P < 0.05). Expression levels of MT1-MMP and TIMP-2 mRNA were correlated with pro-MMP-2 activation ratio (Spearman rank correlation: r = 0.7235, r = 0.7647, P < 0.005). The expression of MMP-9 did not show significant differences between thymomas and thymic carcinomas.

CONCLUSIONSMMP-2, MT1-MMP and TIMP-2 mRNA expression levels are correlated with the histologic subtypes and clinical stages of thymoma. The mRNA expressions of MT1-MMP and TIMP-2 are correlated with the activation ratio of pro-MMP-2. It is speculated that upregulation of MT1-MMP gene expression may induce an activation of pro-MMP-2 through TIMP-2.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; enzymology ; metabolism ; pathology ; Enzyme Activation ; Female ; Humans ; Male ; Matrix Metalloproteinase 2 ; biosynthesis ; genetics ; Matrix Metalloproteinases ; biosynthesis ; genetics ; Matrix Metalloproteinases, Membrane-Associated ; Middle Aged ; Neoplasm Staging ; RNA, Messenger ; biosynthesis ; genetics ; Thymoma ; classification ; enzymology ; metabolism ; pathology ; Thymus Gland ; enzymology ; metabolism ; Thymus Neoplasms ; classification ; enzymology ; metabolism ; pathology ; Tissue Inhibitor of Metalloproteinase-2 ; biosynthesis ; genetics

Breast cancer susceptibility gene, BRCA2, is a tumor suppressor and individuals who inherit one defected copy of BRCA2 allele experience early onset breast cancer or ovarian cancer accompanied by the loss of the wild type allele. Mouse model for Brca2 mutation shows growth retardation and paradoxical occurrence of thymic lymphomas. Thymic lymphomas from Brca2-mutant mice harbor mutations in p53, Bub1, and BubR1, which function as mitotic checkpoint proteins. Therefore, interplay between Brca2 and mitotic checkpoint has been suggested in the maintenance of genetic fidelity, although it has not been assessed whether the unique mutations in Bub1 and BubR1 found in Brca2-mutant mice are responsible for the abolishment of mitotic checkpoint function. This report demonstrates that Bub1 and BubR1 mutant proteins from Brca2(-/-)thymic lymphomas have defects in the phosphorylation and kinetochore localization after spindle damage. Thus, the mutations of Bub1 and BubR1 found in Brca2- mutant mice indeed are responsible for the chromosome instability in Brca2-mutated tumors.
Animals ; BRCA2 Protein/*genetics/*metabolism ; Cell Cycle Proteins ; Cell Transformation, Neoplastic/metabolism ; Mice ; *Mitosis ; Mutation/*genetics ; Phosphorylation ; Protein Kinases/*metabolism ; Protein Transport ; Support, Non-U.S. Gov't ; T-Lymphocytes/metabolism ; Thymus Neoplasms/genetics/*pathology

OBJECTIVETo explore the role of TNFα induced protein 3 interacting protein 1 (TNIP1) in the pathogenesis of myasthenia gravis (MG) among patients with thymoma.

METHODSFrom December 2014 to March 2015, 11 patients with MG associated thymoma (MGT) and 11 non-MG thymoma (NMGT) patients receiving thymectomy were selected. Thymus specimens were obtained during surgery, and peripheral venous blood samples were obtained before the surgery. For the MGT cohorts, peripheral venous blood samples were also collected at 3-6 months after the surgery. TNIP1 mRNA was determined with quantitative real-time PCR (qPCR), and its protein expression was evaluated by Western blotting.

RESULTSFor both thymus specimen and peripheral blood samples, the levels of TNIP1 mRNA and protein in the MGT group were both significantly lower than those of the NMGT patients (P<0.05). For the MGT group, the levels of TNIP1 mRNA and protein of the peripheral blood samples have increased following thymus resection compared with before the surgery.

CONCLUSIONReduced TNIP1 expression may have a role in the pathogenesis of MG for patients with thymoma. Thymectomy may help to recover the expression of TNIP1 among such patients.

Blotting, Western ; DNA-Binding Proteins ; genetics ; metabolism ; Female ; Gene Expression ; Genetic Predisposition to Disease ; genetics ; Humans ; Male ; Myasthenia Gravis ; complications ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Thymectomy ; Thymoma ; complications ; surgery ; Thymus Neoplasms ; complications ; surgery