How to assess the best immunohistochemical panel in the diagnosis of malignant pleural mesothelioma in a pathology lab.

BACKGROUND: malignant pleural mesothelioma (MPM) is a rare tumor with a challenging diagnosis. Even if, clinical data are mandatory to suspect the diagnosis, the positive diagnosis is based on microscopic features. Morphologic features are still the port of call of the diagnosis but their non specific character and the multiplicity of differential diagnoses made the immunohistochemical markers mandatory for the diagnosis. Many antibodies with a positive diagnostic value including claretinin, mesothelin, WT1 and antibodies with a negative diagnostic value including TTF1, EMA, CD15 are recommended by the scientific societies. This is due to the diagnostic limits of every antibody which necessitate the association of multiple antibodies. In the diagnostic demarch, pathologists deal with different antibodies and clones. Even if many recommendations are available, every pathology lab has to experiment its own antibodies in order to optimize the routine diagnostic demarch especially in low-income country. Our aim was to assess the diagnostic value of different antibodies available in our lab and to recommend a decisional flowchart. PATIENTS AND METHODS: we conducted a retrospective study about 30 MPM diagnosed over a 20-year-period. The different techniques were realized manually. The different antibodies used were anti-calretinin, anti-Epithelial Membrane Antigen (EMA), anti-mesothelin, anti-Thyroid Transcription Factor 1 (TTF1), anti-ACE, anti-cytokeratin, anti-vimentin, anti-CD15, anti-cytokeratin 5/6, anti-bcl2, and anti-CD99 and anti-CD34 antibodies. The sensitivity and specificity of these antibodies were assessed. RESULTS: the microscopic exam concluded to an epithelioid mesothelioma (EM) in 17 cases, sarcomatoid mesothelioma (SM) in four cases and biphasic mesothelioma (BM) in nine cases. The immunohistochemical study was performed in all cases. A mean of eight antibodies was used in every case, average 4 to 20 antibodies. The immunohistochemical study was repeated from 2 to 5 times in 15 cases and concerned a mean of 3 antibodies per case. In EM and BM, the antibodies with positive predictive value and highest sensitivity were calretinin, EMA, cytokeratin, and vimentin reaching respectively a sensitivity of 86.2%, 89.7%, 92.9% and 89.3%. The most valuable antibodies with negative predictive value were TTF1, CD15 and ACE that presented a specificity reaching respectively 100%. In sarcomatoid mesothelima, the most sensitive antibody was the cytokeratin antibody. CONCLUSION: these results yielded to a diagnostic flowchart that we can use in routine practice and that is in accordance with the literature findings. Many diagnostic and technical pitfalls have to be known by pathologists when dealing with MPM.

Evaluation of the microvessel density and the expression of metalloproteases 2 and 9 and ttf1 in the different subtypes of lung adenocarcinoma in Tunisia: a retrospective study of 46 cases.

Despite the new available histologic classification of lung cancers, it remains difficult to assess the real prognostic relevance of the different subtypes of lung adenocarcinomas. Facing the prognostic relevance of microvessel density (MVD) and the expression of metalloproteases and thyroid tyrosine factor 1 (TTF1) in different cancers, we tried to compare these parameters in the different subtypes of lung adenocarcinomas. We conducted a retrospective study of 46 adenocarcinomas surgically resected. An immunohistochemical study using the cluster of differentiation 34 (CD34), TTF1, metalloproteases 2 (MMP2), and metalloproteases 9 (MMP9) antibodies was performed on all samples while MVD was evaluated using CD34 antibody. The analyzed cases included 19 acinar, 7 papillary, 1 lepidic, and 19 solid predominant American Thoracic Classification of lung adenocarcinomas (ASK). The higher MVD levels were observed in papillary and acinar subtypes types and a statically significant difference in the MVD was observed in the different subtypes (p< 0,001). This study didn't show significant statistical results concerning MMP and TTF1 expression but it revealed a tendency to an equal expression of these antibodies in the different subtypes. The difference in the MVD between the different subtypes of adenocarcinoma puts emphasis on their prognostic relevance.

Cytological smears and cell blocks on endobronchial aspirates complement each other and allow a higher diagnostic yield.

The accurate diagnosis of lung carcinoma has become compulsory especially after the introduction of new target therapies. Most of the patients are non operable. This fact points out the diagnostic importance of the cytology specimen. Our target was to assess the diagnostic efficacy of bronchial smears and cell blocks by comparing their results with those of the final diagnoses made on biopsies. We conducted a prospective study of 55 bronchial aspirates. It showed a sensitivity of 100% and a specificity of 100% when coupling both techniques. These results put emphasis on the diagnostic efficacy of both bronchial smears and cell blocks in diagnosing bronchial carcinoma.

Prognostic impact of tumor-infiltrating lymphocytes in non-small cell lung carcinomas.

INTRODUCTION: Tumor-infiltrating lymphocytes represent a pivotal component of the host anti-tumor response. Thus, they considerably influence the evolution of cancers including non-small cell lung carcinomas. Even if, this important role is consensual, many discordant results are published in the literature about the prognostic role of the different populations of tumor-infiltrating lymphocytes. The aim of our work was to evaluate the prognostic impact of CD8+, CD4+, and forkhead box protein P3+ lymphocytes in the tumor microenvironment of non-small cell lung carcinomas. METHODS: We conducted a retrospective descriptive study, which included non-small cell lung carcinomas diagnosed in the department of pathology and followed in the medical oncology department of the same hospital between 2011 and 2015. Tumor-infiltrating lymphocytes were analyzed by the immunohistochemical method for forkhead box protein P3, CD4, and CD8. Intratumoral and stromal-labeled lymphocytes were quantified by manual counting at high magnification (×400). Forkhead box protein P3+/CD8+, forkhead box protein P3+/CD4+, and CD8+/CD4+ ratios were subsequently calculated. The prognostic value of tumor-infiltrating lymphocytes was assessed in respect of overall survival, recurrence-free survival, and relapse-free survival. RESULTS: Thirty-nine patients were included. The mean age of patients was 59.6 years. A complete surgical resection (p = 0.009), and a CD8/CD4 ratio (p = 0.008) were prognostic factors for overall survival. Complete surgical resection (p = 0.003), the forkhead box protein P3/CD8 (p = 0.005), and forkhead box protein P3/CD4 (p = 0.037) ratios were prognostic factors for recurrence-free survival. The CD8+ tumor-infiltrating lymphocytes rate (p = 0.037) was a prognostic factor for relapse-free survival with a threshold of 67.8/high power field. Microscopic subtype (p = 0.037) was a prognostic factor for relapse-free survival when only adenocarcinoma and squamous cell carcinoma were considered. In multivariate analysis, age (p = 0.004) and a CD8/CD4 ratio (p = 0.016) were independent predictors of overall survival. CONCLUSION: Despite the limitations of our study, our results confirm the prognostic value of tumor-infiltrating lymphocytes in non-small cell lung carcinomas and the importance of the combined quantification of their different subpopulations.