Faculty Bibliography

Currently there is no established guidance on how to process and evaluate resected lung cancer specimens following neoadjuvant therapy in the setting of clinical trials and clinical practice. There is also a lack of precise definitions on the degree of pathologic response, including major pathologic response (MPR) or complete pathologic response (CPR). In other cancers such as osteosarcoma, colorectal, breast and esophageal carcinomas, there have been multiple studies investigating pathologic assessment of the effects of neoadjuvant therapy including some detailed recommendations on how to handle these specimens. A comprehensive mapping approach to gross and histologic processing of osteosarcomas following induction therapy has been used for over 40 years. The purpose of this article is to outline detailed recommendations on how to process lung cancer resection specimens and to define pathologic response including MPR and CPR following neoadjuvant therapy. A standardized approach is recommended to assess the percentages of: 1) viable tumor, 2) necrosis and 3) stroma (including inflammation and fibrosis) with a total adding up to 100%. This is recommended for all systemic therapies including chemotherapy, chemoradiation, molecular targeted therapy, immunotherapy or any future novel therapies yet to be discovered whether administered alone or in combination. Specific issues may differ for certain therapies such as immunotherapy, but the grossing process should be similar and the histologic evaluation should contain these basic elements. Standard pathologic response assessment should allow for comparisons between different therapies and correlations with disease free survival and overall survival in ongoing and future trials. The International Association for the Study of Lung Cancer (IASLC) has an effort to collect such data from existing and future clinical trials. These recommendations are intended as guidance for clinical trials, although it is hoped they can be viewed as suggestion for good clinical practice outside of clinical trials, to improve consistency of pathologic assessment of treatment response.

The recent development of immune checkpoint inhibitors (ICI) has led to promising advances in the treatment of non-small cell and small cell lung cancer patients with advanced or metastatic disease. Most of ICI target the PD-1/PD-L1 axis with the aim of restoring anti-tumor immunity. Multiple clinical trials for ICI have examined a predictive value of PD-L1 protein expression in tumor cells and/or tumor-infiltrating immune cells by immunohistochemistry (IHC), for which different assays with specific IHC platforms were applied. Of those, some PD-L1 IHC assays have been validated for the prescription of the corresponding agent for first- or second-line treatment. However, not all laboratories are equipped with the dedicated platforms and many laboratories have set up in-house or laboratory developed tests, which are more affordable than generally expensive clinical trial-validated assays. Although PD-L1 IHC test is now deployed in the most pathology laboratories, its appropriate implementation and interpretation are critical as a predictive biomarker and can be challenging due to the multiple antibody clones and platforms or assays available and given the typically small size of samples provided. As many articles have been published since the issue of the IASLC Atlas of PD-L1 immunohistochemistry testing in lung cancer, this review by the IASLC pathology committee provides updates on the indications of ICI for lung cancer in 2019, and discusses important considerations on pre-analytical, analytical and post-analytical aspects of PD-L1 IHC testing, including specimen type, validation of assays, external quality assurance and training.

INTRODUCTION/BACKGROUND:Overexpression of the mesenchymal-epithelial transition (MET) receptor, a receptor tyrosine kinase, can propel the growth of cancer cells and portends poor prognoses for patients with lung cancer. Evaluation of MET by immunohistochemistry is challenging, with MET protein overexpression varying from 20% to 80% between lung cancer cohorts. Clinical trials using MET protein expression to select patients have also reported a wide range of positivity rates and outcomes. MATERIALS AND METHODS/METHODS:To overcome this variability, the Lung Cancer Mutation Consortium Pathologist Panel endeavored to standardize the evaluation of MET protein expression with "Round Robin" conferences. This panel used randomly selected Aperio-scanned formalin-fixed paraffin-embedded lung cancer specimens stained by MET immunohistochemistry for the Lung Cancer Mutation Consortium 2.0 study (N=838). Seven pathologists in separate laboratories scored images of 5 initial cases and 2 subsequent rounds of 39 cases. The pathologists' scores were compared for consistency using the intraclass correlation coefficient. Issues affecting reproducibility were discussed in Round Robin conferences between rounds, and steps were taken to improve scoring consistency, such as sharing reference materials and example images. RESULTS:The overall group intraclass correlation coefficient comparing the consistency of scoring improved from 0.50 (95% confidence interval, 0.37-0.64) for the first scoring round to 0.74 (95% confidence interval, 0.64-0.83) for the second round. DISCUSSION/CONCLUSIONS:We found that the consistency of MET immunohistochemistry scoring is improved by continuous training and communication between pathologists.

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.

Background & Objectives: Ciliated muconodular papillary tumour (CPMT) is a rare benign lesion, which occurs in the periphery of the lung and is characterised by papillary architecture, intra-alveolar mucin and the presence of non-atypical ciliated-columnar, basal and mucous cells. Since its introduction in 2002 by Ishikawa et al, this entity counts a few reports in the literature, which have primarily occurred in East Asia. Although not in the 2015WHO classification, CPMT represents a frank neoplastic process, harbouring genetic alterations including BRAF and EGFR mutations. The goal of this study was to characterise the clinicopathologic features of CPMT diagnosed at a tertiaty care institution in the U.S.
Method(s): Nine cases with characteristic features of classic and nonclassic CPMT from New York University Tisch Hospital and Bellevue Hospital from 2016 to 2019 were identified. Clinical and pathologic data were reviewed.
Result(s): CPMTs were identified in 3 Male and 6 Female patients, whose age ranged from 47 to 82 years old. The lesions were predominantly found in the right lung and had a median size of 6 mm. Six (6) cases represented classic CPMTs, while 3 cases lacked the full spectrum of CPMT diagnostic features, and were classified as non-classic CPMTs. While in 7 cases, surgical resection was performed due to radiologic diagnosis of a peripheral nodule, in 2 cases, small CPMTs were incidental findings in resections performed for a dominant lesion, which was either adenocarcinoma, non-mucinous type (case 2) or atypical carcinoid (case 8). All lesions showed the characteristic immunohistochemical TTF-1 stain of columnar cells and p63 or p40 stain of basal cells. Two out of four (2/4) cases stained for BRAF-V600E showed uniform staining of all 3 cellular components of the lesion. The data are summarized on Table 1.
Conclusion(s): CPMTs although infrequent are now increasingly recognized and their incidence appears higher than reported in western literature. Interestingly, this self-limited tumour shares similar driver mutations with lung adenocarcinoma. Further studies will include a comprehensive immunohistochemical and molecular characterization of these nine cases and comparison with morphologically similar non-neoplastic processes, like bronchiolar metaplasia

Fungi of the Paracoccidioides genus are the etiological agents of paracoccidioidomycosis (PCM), a systemic mycosis restricted to the countries of Latin America. Currently, the Paracoccidioides complex is represented by Paracoccidioides lutzii, Paracoccidioides americana, Paracoccidioides brasiliensis, Paracoccidioides restrepiensis, and Paracoccidioides venezuelensis. Even with advances in techniques used for diagnosing fungal diseases, high rates of false-positive results for PCM are still presented. Additionally, there is no efficient antigen that can be used to follow up the efficiency of patient treatment. The immunoproteomic is considered a powerful tool for the identification of antigens. In addition, antigens are molecules recognized by the immune system, which make them excellent targets for diagnostic testing of diseases caused by microorganisms. In this vein, we investigated which antigens are secreted by species representing Paracoccidioides complex to increase the spectrum of molecules that could be used for future diagnostic tests, patient follow-up, or PCM therapy. To identify the profile of antigens secreted by Paracoccidioides spp., immunoproteomic approaches were used combining immunoprecipitation, followed by antigen identification by nanoUPLC-MS^E-based proteomics. Consequently, it was possible to verify differences in the exoantigen profiles present among the studied species. Through a mass spectrometry approach, it was possible to identify 79 exoantigens in Paracoccidioides species. Using bioinformatics tools, two unique exoantigens in P. lutzii species were identified, as well as 44 epitopes exclusive to the Paracoccidioides complex and 12 unique antigenic sequences that can differentiate between Paracoccidioides species. Therefore, these results demonstrate that Paracoccidioides species have a range of B-cell epitopes exclusive to the complex as well as specific to each Paracoccidioides species. In addition, these analyses allowed us the identification of excellent biomarker candidates for epidemiology screening, diagnosis, patient follow-up, as well as new candidates for PCM therapy.

Introduction: Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive hereditary disorder characterized by oculocutaneous albinism and bleeding diathesis. Transplantation is often conducted to treat lung fibrosis, which is the most fatal complication of this disease. While the literature discusses the diagnosis of HPS based on genetic testing, radiology, and electron microscopic (EM) findings of platelet granules, there is a paucity of images in the literature illustrating the pulmonary histopathologic and EM features of HPS. Case Report: Here we present striking histopathologic and EM images from a case of pulmonary fibrosis due to HPS in a 48-year-old female. The patient presented with restrictive lung disease and bilateral decreased breath sounds with diffuse crackles. She was clinically diagnosed with HPS and underwent bilateral lung transplant. On histopathology, both pneumonectomy specimens showed diffuse interstitial fibrosing and cellular pneumonitis with end-stage remodeling and type II pneumocyte (PC-II) hyperplasia. The PC-IIs had abundant foamy cytoplasm and compressed scalloped nuclei. Alveolar macrophages contained fine brown granules positive for PAS-D stain. EM analysis revealed that the PC-IIs contained numerous lamellated myelin bodies (so-called giant lamellar body degeneration) suggestive of surfactant admixed with lipid and luminal microvilli. The pigmented alveolar macrophages also contained lamellated myelin bodies, as well as clusters of single membrane-bound structures with varying size and electron density admixed with vacuolar and granular debris suggestive of ceroid deposits.
Conclusion(s): Based on light microscopy, histochemical analysis, EM, and clinical presentation, it was concluded that our findings were consistent with pulmonary changes as seen in HPS