Faculty Bibliography

Background: When the first diagnosis of a well-differentiated neuroendocrine neoplasm (WDNEN) is made on a biopsy, crush artifact may impede mitotic counting, and the Ki-67 proliferative index (KPI) plays a more important role in grading. Few studies have examined the reliability of KPI in the grading of metastatic (met) WDNEN.
Design(s): Cases were retrieved from 2008-19. For each primary (1degree) and met, a 40x hotspot image of a Ki-67 stained slide was taken. KPI was analyzed by the ImmunoRatio Plugin using ImageJ software. All were validated by independent manual counting. In 1 case, crush artifact precluded use of ImageJ. If multiple mets were present, the largest was selected. Cytology and cases with fewer than 100 cells were omitted. Tumors were graded as G1(KPI<3%), G2(KPI 3-20%), or G3(KPI>20%). Grade and KPI were compared between each 1degree and met.
Result(s): 67 cases, including 38 mets from 29 1degree WDNEN, were evaluated. There were 12, 2, 2, 1, 17, and 4 mets from lung, thymus, middle ear, pancreas, small bowel, & colon respectively. The greatest variations in KPI from 1degree to met were seen in lung compared to all other sites. In 24/38(63%) of all mets, the grade was the same as 1degree. In 14/38(37%) of all mets, the grade was different: 4/14(29%) were lower while 10/14(71%) were higher than 1degree. In mets from lung, 2 had lower, 6 had the same, & 4 had higher grade. In mets from middle ear, the grades increased. In mets from small bowel 2 had lower, 12 had the same, and 3 had higher grade. In mets from colon 3 had the same and 1 had higher grade. And in mets from thymus & pancreas, the grades remained the same. See Fig 1. 3 mets were diagnosed before 1degree (2 days to 2 months). Mets with higher grade than 1degree tended to have longer time interval between 1degree and met, but this was not significant at the 95% confidence level (Kruskal-Wallis test, p=0.08). 28 mets were regional and 10 were distant. There was no correlation between met site and grade change (Person Chi-square, p=0.33). Also see Table 1. (Table presented)
Conclusion(s): Our study showed that in most met WDNEN (63%), the grade remained the same as the 1degree. The grade was higher in 10/38(26%) and lower in 4/38(11%). There was a trend toward higher grade in mets that occurred at a longer time interval after the 1degree. Fig 2 shows a potential diagnostic pitfall when the met shows much higher KPI than 1degree. In conclusion, if a met WDNEN is suspected as a firsttime diagnosis, KPI must be used cautiously for classification of WDNEN since over/under-grading may occur

INTRODUCTION/BACKGROUND:Molecular and immunologic breakthroughs are transforming the management of thoracic cancer, although advances have not been as marked for malignant pleural mesothelioma (MPM) where pathologic diagnosis has been essentially limited to three histologic subtypes. METHODS:A multidisciplinary group (pathologists, molecular biologists, surgeons, radiologists and oncologists), sponsored by EURACAN/IASLC met in 2018, to critically review the current classification. RESULTS:Recommendations include: 1) classification should be updated to include architectural patterns, and stromal and cytologic features that refine prognostication 2) subject to data accrual, malignant mesothelioma in situ could be an additional category, 3) grading of epithelioid MPMs should be routinely undertaken, 4) favorable/unfavorable histologic characteristics should be routinely reported, 5) clinically relevant molecular data (PD-L1, BAP1, CDKN2A) should be incorporated into reports, if undertaken, 6) other molecular data should be accrued as part of future trials 7) resection specimens (i.e. extended pleurectomy/decortication and extrapleural pneumonectomy) should be pathologically staged with smaller specimens being clinically staged, 8) ideally, at least 3 separate areas should be sampled from the pleural cavity, including areas of interest identified on pre-surgical imaging, 9) image-acquisition protocols/imaging terminology should be standardized to aid research/refine clinical staging, 10) multidisciplinary tumor boards should include pathologists to ensure appropriate treatment options are considered, 11) all histologic subtypes should be considered potential candidates for chemotherapy, 12) patients with sarcomatoid or biphasic mesothelioma should not be excluded from first line clinical trials unless there is a compelling reason, 13) tumor subtyping should be further assessed in relation to duration of response to immunotherapy, 14) systematic screening of all patients for germline mutations is not recommended, in the absence of a family history suspicious for BAP1 syndrome. CONCLUSION/CONCLUSIONS:These multidisciplinary recommendations for pathology classification and application will allow more informative pathologic reporting and potential risk stratification, to support clinical practice, research investigation and clinical trials.

Anterior mediastinal lesions while rare, are heterogeneous in etiology, with broad differential considerations that may be narrowed by drawing on discriminating clinical, radiologic, and histopathologic features. This manuscript will review the radiographic and pathologic correlation of anterior mediastinal lesions of thymic, lymphomatous, and germ-cell origin.

The purpose of this study was to identify the optimal tracer kinetic model from T₁ -weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data and evaluate whether parameters estimated from the optimal model predict tumor aggressiveness determined from histopathology in patients with papillary thyroid carcinoma (PTC) prior to surgery. In this prospective study, 18 PTC patients underwent pretreatment DCE-MRI on a 3 T MR scanner prior to thyroidectomy. This study was approved by the institutional review board and informed consent was obtained from all patients. The two-compartment exchange model, compartmental tissue uptake model, extended Tofts model (ETM) and standard Tofts model were compared on a voxel-wise basis to determine the optimal model using the corrected Akaike information criterion (AICc) for PTC. The optimal model is the one with the lowest AICc. Statistical analysis included paired and unpaired t-tests and a one-way analysis of variance. Bonferroni correction was applied for multiple comparisons. Receiver operating characteristic (ROC) curves were generated from the optimal model parameters to differentiate PTC with and without aggressive features, and AUCs were compared. ETM performed best with the lowest AICc and the highest Akaike weight (0.44) among the four models. ETM was preferred in 44% of all 3419 voxels. The ETM estimates of K^trans in PTCs with the aggressive feature extrathyroidal extension (ETE) were significantly higher than those without ETE (0.78 ± 0.29 vs. 0.34 ± 0.18 min^-1 , P = 0.005). From ROC analysis, cut-off values of K^trans , v_e and v_p , which discriminated between PTCs with and without ETE, were determined at 0.45 min^-1 , 0.28 and 0.014 respectively. The sensitivities and specificities were 86 and 82% (K^trans ), 71 and 82% (v_e ), and 86 and 55% (v_p ), respectively. Their respective AUCs were 0.90, 0.71 and 0.71. We conclude that ETM K^trans has shown potential to classify tumors with and without aggressive ETE in patients with PTC.

AIMS/OBJECTIVE:The 2015 WHO classification for lung adenocarcinoma (ACA) provides criteria for adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) and invasive adenocarcinoma (INV), but differentiating these entities can be difficult. As our understanding of prognostic significance increases, inconsistent classification is problematic. This study assesses agreement within an international panel of lung pathologists and identifies factors contributing to inconsistent classification. METHODS AND RESULTS/RESULTS:Sixty slides of small lung ACAs were reviewed digitally by six lung pathologists in three rounds, with consensus conferences and examination of elastic stains in round 3. The panel independently reviewed each case to assess final diagnosis, invasive component size and predominant pattern. The kappa value for AIS and MIA versus INV decreased from 0.44 (round 1) to 0.30 and 0.34 (rounds 2 and 3). Interobserver agreement for invasion (AIS versus other) decreased from 0.34 (round 1) to 0.29 and 0.29 (rounds 2 and 3). The range of the measured invasive component in a single case was up to 19.2 mm among observers. Agreement was excellent in tumours with high-grade cytology and fair with low-grade cytology. CONCLUSIONS:Interobserver agreement in small lung ACAs was fair to moderate, and improved minimally with elastic stains. Poor agreement is primarily attributable to subjectivity in pattern recognition, but high-grade cytology increases agreement. More reliable methods to differentiate histological patterns may be necessary, including refinement of the definitions as well as recognition of other features (such as high-grade cytology) as a formal part of routine assessment.

Electronic-cigarettes (E-cigs) are marketed as a safe alternative to tobacco to deliver the stimulant nicotine, and their use is gaining in popularity, particularly among the younger population. We recently showed that mice exposed to short-term (12 wk) E-cig smoke (ECS) sustained extensive DNA damage in lungs, heart, and bladder mucosa and diminished DNA repair in lungs. Nicotine and its nitrosation product, nicotine-derived nitrosamine ketone, cause the same deleterious effects in human lung epithelial and bladder urothelial cells. These findings raise the possibility that ECS is a lung and bladder carcinogen in addition to nicotine. Given the fact that E-cig use has become popular in the past decade, epidemiological data on the relationship between ECS and human cancer may not be known for a decade to come. In this study, the carcinogenicity of ECS was tested in mice. We found that mice exposed to ECS for 54 wk developed lung adenocarcinomas (9 of 40 mice, 22.5%) and bladder urothelial hyperplasia (23 of 40 mice, 57.5%). These lesions were extremely rare in mice exposed to vehicle control or filtered air. Current observations that ECS induces lung adenocarcinomas and bladder urothelial hyperplasia, combined with our previous findings that ECS induces DNA damage in the lungs and bladder and inhibits DNA repair in lung tissues, implicate ECS as a lung and potential bladder carcinogen in mice. While it is well established that tobacco smoke poses a huge threat to human health, whether ECS poses any threat to humans is not yet known and warrants careful investigation.

Background: PD-L1 immunohistochemistry (IHC) is now performed for advanced non-small cell lung cancer (NSCLC) patients to examine their eligibility for pembrolizumab treatment, as well as in Europe for durvalumab therapy after chemoradiation for stage III NSCLC patients. Four PD-L1 clinical trial validated assays (commercial assays) have been FDA/EMA approved or are in vitro diagnostic tests in multiple countries, but high running costs have limited their use; thus, many laboratories utilize laboratory-developed tests (LDTs). Overall, the PD-L1 testing seems to be diversely implemented across different countries as well as across different laboratories.
Method(s): The Immune biomarker working group of the IASLC international pathology panel conducted an international online survey for pathologists on PD-L1 IHC testing for NSCLC patients from 2/1/2019 to 5/31/2019. The goal of the survey was to assess the current prevalence and practice of the PD-L1 testing and to identify issues to improve the practice globally. The survey included more than 20 questions on pre-analytical, analytical and post-analytical aspects of the PDL1 IHC testing, including the availability/type of PD-L1 IHC assay(s) as well as the attendance at a training course(s) and participation in a quality assurance program(s).
Result(s): 344 pathologists from 310 institutions in 64 countries participated in the survey. Of those, 38% were from Europe (France 13%), 23% from North America (US 17%) and 17% from Asia. 53% practice thoracic pathology and 36%, cytopathology. 11 pathologists from 10 countries do not perform PD-L1 IHC and 7.6% send out to outside facility. Cell blocks are used by 75% of the participants and cytology smear by 9.9% along with biopsies and surgical specimens. Pre-analytical conditions are not recorded in 45% of the institutions. Clone 22C3 is the most frequently used (61.5%) (59% with the commercial assay; 41% with LDT) followed by clone SP263 (45%) (71% with the commercial assay; 29% with LDT). Overall, one or several LDTs are used by 57% of the participants. A half of the participants reported turnaround time as 2 days or less, while 13% reported it as 5 days or more. Importantly, 20% of the participants reported no quality assessment, 15%, no formal training session for PD-L1interpretation and 14%, no standardized reporting system.
Conclusion(s): There is marked heterogeneity in PD-L1 testing practice across individual laboratories. In addition, the significant minority reported a lack of quality assurance, formal training and/or standardized reporting system that need to be established to improve the PD-L1 testing practice globally. Keywords: global survey, NSCLC, PD-L1 immunohistochemistry
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The accurate diagnosis of mesothelioma is critical for the appropriate clinical management of this cancer. Many issues complicate making the diagnosis of mesothelioma including the presence of reactive mesothelial cells in benign pleural effusions, the heterogeneity of mesothelioma histopathology, the relatively high incidence of other epithelial malignancies that metastasize to the pleura, and primary sarcomas that arise within the pleura. Given the rapidly evolving field of molecular profiling and the need for translational correlates in mesothelioma clinical trials, the National Cancer Institute-International Association for the Study of Lung Cancer-Mesothelioma Applied Research Foundation Clinical Trials Planning Meeting was convened in March 2017 to develop a consensus on standard pathology guidelines for future NCI-sponsored clinical trials in mesothelioma. This consensus statement covers recommendations for specimen handling, pathologic classification and diagnosis, biobanking and tissue correlative studies.

Background: Tumor grading has been a traditional component of the pathologic evaluation and in many organ systems, tumor grading offers guideline to therapy and patient management. The latter has not been applied to NSCLC. However, considering the new advances in therapy modalities for NSCLC and advances in adenocarcinoma classification, it is now clear that there are different types of adenocarcinomas and these tumors should not be treated the same way. The 2015 WHO classification of pulmonary adenocarcinoma based on the predominant histological pattern has consistently been found to correlate with prognosis. There is broad agreement that the five histological patterns (lepidic, acinar, papillary, solid and micropapillary) are important prognostic indicators. Recent studies have proposed the inclusion of a number of additional pathologic features (the role of secondary patterns, non-traditional pattern such as cribriform and complex glandular patterns, nuclear grade, mitotic counts, presence of spread through alveolar space (STAS), and necrosis.) that also have prognostic value. The addition of these histological features to the predominant pattern could offer greater refinement of a grading scheme. Supplementing the classification of lung adenocarcinomas with an objective grading system will help define prognostic groups that could benefit from the changing landscape of emerging management and treatment options. Contrary to adenocarcinoma, there has been little advancements in the histological prognostic indicators in squamous cell carcinoma of the lung. Isolated reports have suggested that the presence of tumor budding into the stroma is the sole indicator of poor prognosis. Keratinization, which has been traditionally used to grade these tumors, does not appear to have prognostic value. However, a systematic evaluation of prognostic markers in these tumors have not been carried out. A summary of the current efforts in squamous cell carcinoma will be discussed. The IASLC pathology panel has proposed a systematic study to evaluate a set of histological criteria that have been described as prognostic indicators in adenocarcinoma aimed at establishing an objective grading system of invasive lung adenocarcinoma.
Design(s): A multi-institutional study involving well-annotated multiple cohorts of stage 1 adenocarcinomas with at least five years of follow up were evaluated. Annotation included an estimate of the percentage for each histological pattern present for each case; nuclear grade, cytology grade; and mitotic counts with pattern hot-spot association, presence of STAS, and necrosis. A cohort of 284 cases was used as a training set. Univariate analysis was performed to identify significant associations of histological features with recurrence-free survival and overall survival. ROC curve analysis was used to select the best model based on combinations of several features and its association with disease recurrence or death of disease. The results were validate on independent cohorts of 212 cases.
Result(s): Review of the literature showed that there are many variation in the classification and definitions on non-traditional patterns. In our cohorts, cribriform and complex glandular patterns followed similar curve as traditional high grade patterns (solid and micropapillary), therefore these non-traditional pattern were defined as patterns of high grade in the model. Another are of variation is the percentage of high grade pattern that can influence outcome. Therefore, the cut-off for a high grade pattern associated with recurrence or death of disease was also established in the training cohort and correspond to 20%. Therefore, amounts smaller than 20% of high grade pattern did not influence outcome. In the training cohort (n=284) all parameters tested, predominant patterns, mitotic count, nuclear grade, cytological grade, and STAS (but not necrosis) were found to have significant prognostic value on a univariate analysis. A Baseline Model composed of Age + Gender + Race + Type of surgery + Pathological Stage; showed an AUC of 0.673. In an attempt to improve this curve, histological parameters were added to the model. The addition of only the predominant pattern to the baseline increases the AUC to 0.698. A model based on the combination of predominant pattern paired with the second predominant pattern was found to have the highest AUC (0.765), followed by a combination of predominant pattern plus worse pattern (AUC=0.74). Addition of other histological features (nuclear grade, mitotic count, STAS etc.) did not significantly improve the model. Similar results were found in the validation set (N=212). The combination of the two most predominant patterns showed an AUC = 0.763, followed by a combination of predominant + worse pattern with AUC = 0.766. Addition of other histological features did not show improvement of the model. There was no statistical difference between the models using the two most predominant patterns and the predominant plus worse. There was good reproducibility scores for the 2 models
Conclusion(s): Our results suggest that an objective grading system for pulmonary adenocarcinoma is possible. Considering that there is no significant differences between a model that accounts for the 2 most predominant pattern and another composed of the predominant plus worse pattern. The IASLC pathology panel proposes the later to be used, because pathologists traditionally grade tumors by the worse component. Therefore, histologic assessment of the predominant pattern and worse pattern, would represent the most parsimonious and prognostic grading system for stage I lung adenocarcinomas. The use of the model in two other independent cohorts of adenocarcinomas (stages 1-3), as well as a reproducibility study will be discussed. Keywords: tumor grading, adenocarcinoma, prognosis
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Introduction: Desmoplastic mesothelioma (DMM), a rare histological subtype of malignant pleural mesothelioma (MPM), is lethal and has very poor prognosis. Metastasis is commonly reported in DMM compared to other histological subtypes. Here we report a case of DMM with good survival (>1 year) despite lymph node metastasis. Case Report: A 62-year-old female with a history of smoking and possible asbestos exposure presented with cough and wheeze in 2012. Computed tomography (CT) revealed left-sided pleural plaques and multiple groundglass pulmonary nodules. In 2017, repeat CT showed increased diffuse left nodular pleural thickening. Positron emission tomography revealed hypermetabolic, nodular pleural thickening in the hemithorax, compatible with neoplasia. Needle biopsy in January 2018 showed pleural tissue with haphazard, nodular growth of spindled mesothelial cells, suspicious for desmoplastic mesothelioma. Definitive diagnosis was not possible due to lack of fat invasion and absence of supportive evidence by immunohistochemical stains. The patient underwent pleurectomy in February 2018. On histopathology, the majority of the tumor showed a desmoplastic pattern, composed of malignant spindled cells arranged haphazardly in a dense hyalinized stroma with chronic inflammatory infiltrate. AE1/AE3, calretinin, and D2-40 immunohistochemical stains highlighted the infiltrating neoplastic cells, which were negative for WT-1. BAP-1 was retained. The pattern of immunoreactivity supported the diagnosis of DMM. The tumor also involved visceral pleura, pulmonary parenchyma, and pericardium. It invaded into fat and displayed lymphovascular invasion. A metastatic focus of DMM was present in a lymph node. The tumor was staged as pT3N1. On recent examination, the patient only had complaints of mild breathlessness and stable hydro-pneumothorax, without any other comorbidities.
Conclusion(s): Our finding is unusual, since among the mesothelioma subtypes, DMM has the shortest survival, usually not more than 6 months. We report an extremely rare case of DMM with survival of >1 year despite invasion of lung parenchyma and lymph node metastasis