ABSTRACT
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.
Subject(s)
Male , Female , Humans , Adult , Middle Aged , Thymoma/genetics , In Situ Hybridization, Fluorescence , Transcription Factors/genetics , Mutation , Thymus Neoplasms/geneticsABSTRACT
Objective: From the economic point of view, this study was to systematically assess the status quo on lung cancer screening in the world and to provide reference for further research and implementation of the programs, in China. Methods: PubMed, EMbase, The Cochrane Library,CNKI and Wanfang Data were searched to gather papers on studies related to economic evaluation regarding lung cancer screening worldwide, from the inception of studies to June 30(th), 2018. Basic characteristics, methods and main results were extracted. Quality of studies was assessed. Cost were converted to Chinese Yuan under the exchange rates from the World Bank. The ratio of incremental cost-effectiveness ratio (ICER) to local GDP per capita were calculated. Results: A total of 23 studies (only 1 randomized controlled trial) were included and the overall quality was accepted. 22 studies were from the developed countries. Nearly half of the studies (11 studies) took 55 years old as the starting age of the screening program. Smoking history was widely applied for the selection of criteria on target populations (18). Low-dose computed tomography (LDCT) was involved in every study used to evaluate the economic effectiveness. Annual (17) and once-life time (7) screening were more common frequencies. 22 studies reported ICERs for LDCT screening, compared to no screening, of which 17 were less than 3 times local GDP per capita, and were considered as cost-effectiveness, according to the WHO's recommendation. 15 and 7 studies reported ICERs for annual and once-life time screening, of which 12 and 7 studies were in favor the results of their cost-effectiveness, respectively. Additionally, the cost-effectiveness of once-lifetime screening was likely to be superior to the annual screening. Differences of cost-effectiveness among the subgroups, by starting age or by the smoking history, might exist. Conclusions: Based on the studies, evidence from the developed countries demonstrated that LDCT screening programs on lung cancer, implemented among populations selected by age and smoking history, generally appeared more cost-effective. Combined with the local situation of health resource, the findings could provide direction for less developed regions/countries lacking of local evidence. Low frequency of LDCT screening for lung cancer could be adopted when budget was limited. Data on starting ages, smoking history and other important components related to the strategy of screening programs, needs to be precisely evaluated under the situation of local population.