Clinicopathological and molecular features of metaplastic thymoma / 中华病理学杂志

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.

Papillary renal neoplasm with reverse polarity: a clinicopathological analysis / 中华病理学杂志

Objective: To study the clinical pathological characteristics, immunophenotype, molecular changes and prognosis of the papillary renal neoplasm with reverse polarity (PRNRP). Methods: Nine cases of PRNRP, diagnosed from 2013 to 2019, were retrieved from the Department of Pathology of Nanjing Jinling Hospital, Nanjing University School of Medicine. Histomorphology, immunophenotype and molecular genetics were analyzed with review of the literatures. Results: There were five male and four female patients, aged from 49 to 70 years, with an average age of 60.1 years. During a mean follow-up of 29 months, one patient died for other cause, and the others survived without disease. Microscopically, the tumor cells arranged in papillary structure with a fibrovascular core, the surface of which was covered with a single layer of cuboidal or columnar cells. The most prominent feature was that the tumor nuclei located at the top of the cytoplasm far from the basement membrane, and they were monotonous in size and arranged neatly with no or few nucleoli. Immunohistochemically, all nine cases of PRNRP showed diffuse positive expression of CK7 and E-cadherin, various degrees of P504s expression, and no expression of CD10 and CD117, with a Ki-67 index of 1%-3%. Unlike other papillary renal cell carcinoma, the nine cases of PRNRP all showed characteristic positive expression of GATA3. The fluorescence in situ hybridization assay showed that the majority of PRNRPs (8/9) did not have triploids on chromosomes 7 and 17. The sequencing of the KRAS gene confirmed the presence of a nonsense KRAS mutation in 8 of the 9 cases. Conclusions: PRNRP is a subtype of papillary renal cell carcinoma with characteristic morphological, immunophenotypic and molecular features, and indolent behaviors. More data are needed to define PRNRP as "carcinoma", and a definitive diagnosis of PRNRP is of great significance for proper treatment choice and accurate prognostication.

DNA re-use after immunohistochemical staining of FFPE sections of non-small cell lung cancer / 医学研究生学报

Objective　The purpose of this study was to evaluate the quality of DNA from the formalin-fixed paraffin-embedded (FFPE) specimens of non-small cell lung cancer (NSCLC) after immunohistochemical staining and investigate DNA extraction by immunohistochemical staining of the specimens in small in number or difficult to obtain and the feasibility of related molecular tests.　Methods　We randomly collected 50 FFPE biopsy specimens of NSCLC in our Department of Pathology from June 2017 to December 2017 and sliced each into 12 sections, of which, 6 were directly subjected to DNA extraction (the control group) and the other 6 to immunohistochemical Envision two-step staining for DNA extraction (the experimental group). Then, we detected the mutations of the epidermal growth factor receptor (EGFR), kirsten rat sarcoma viral oncogene (KRAS) and V-raf murine sarcoma viral oncogene homolog B (BRAF) in all the DNAs extracted.　Results　No statistically significant differences were observed between the experimental and control groups in the DNA concentration and purity in the 50 FFPE biopsy specimens of NSCLC (P>0.05). Of the 50 NSCLC FFPE specimens of the experimental group, 20 (40%) showed the mutation of EGFR, 8 (16%) exhibited that of KRAS, and 5 (10%) manifested that of BRAF. In the other 50 specimens of the control group, 33 showed the mutations of EGFR, KRAS and BRAF. A 100% consistency was found in the results of detection between the experimental and control groups (P=0.000, Kappa=1.000).　Conclusion　 High-quality DNA can be extracted after immunohistochemical staining from NSCLC FFPE specimens, especially those small in number or difficult to obtain, and can be used for downstream molecular analysis of target genes, which is a good method for specimen recycling and provides a solution for subsequent molecular test of scarce or difficult-to-obtain clinical samples.

Primary testicular diffuse large B-cell lymphoma: A clinicopathological analysis / 中华男科学杂志

Objective@#To investigate the clinicopathological features, immunophenotype and treatment of primary testicular diffuse large B-cell lymphoma (DLBCL).@*METHODS@#We retrospectively analyzed the pathomorphological characteristics and immunohistochemical markers of 23 cases of primary testicular DLBCL as well as their clinicopathological features with a review of the relevant literature. The patients were aged 48－76 (mean 61.4) years, 82.6% over 50 years, and all clinically presented with painless progressive unilateral testicular swelling, 9 cases in the left and the other 14 in the right testis.@*RESULTS@#Histologically, the lymphomas were composed of large atypical cells with prominent karyokinesis and diffusely infiltrated the testicular parenchyma. The neoplastic cells were positive for B-cell markers. Five of the patients were followed up for 2 to 32 months, of whom 4 survived and 1 died at 9 months.@*CONCLUSIONS@#Primary testicular DLBCL is a rare tumor with an invasive biological behavior, mostly found in elderly males and easily misdiagnosed or missed in diagnosis. Histopathology plays a key role and immunohistochemical markers are of high value in the definite diagnosis and differential diagnosis of the tumor.