BAP1 Loss, Nuclear Grading, and Nonepithelioid Features in the Diagnosis of Mesothelioma in Italy: Nevermore without the Pathology Report

The pathologic diagnosis of pleural mesothelioma is generally based on international guidelines, but no compulsory points based on different drugs approvals in different European countries are required to be reported. According to the last (2021) edition of the World Health Organization classification of pleural tumors, the nuclear grade of epithelioid-type mesothelioma should be always inserted in the pathologic report, while the presence of BRCA-associated protein-1 (BAP1) (clone C4) loss and a statement on the presence of the sarcomatoid/nonepithelioid component are fundamental for both a screening of patients with suspected BAP1 tumor predisposition syndrome and the eligibility to perform first-line immunotherapy at least in some countries. Several Italian experts on pleural mesothelioma who are deeply involved in national scientific societies or dedicated working groups supported by patient associations agreed that the pathology report of mesothelioma of the pleura should always include the nuclear grade in the epithelioid histology, which is an overt statement on the presence of sarcomatoid components (at least 1%, in agreement with the last classification of pleural mesothelioma) and the presence of BAP1 loss (BAP1-deficient mesothelioma) or not (BAP1-retained mesothelioma) in order to screen patients possibly harboring BAP1 tumor predisposition syndrome. This review aims to summarize the most recent data on these three important elements to provide evidence regarding the possible precision needs for mesothelioma.

Updates on grading mesothelioma

Mesothelioma is a rare disease with an historically poor prognosis. Over the past decade, a grading system has been developed that is a powerful prognostic tool in epithelioid mesothelioma. Grading of epithelioid mesothelioma is now required or strongly recommended by expert consensus, the College of American Pathologists, the World Health Organization, and the International Mesothelioma Interest Group. The original nuclear grading system for epithelioid mesothelioma, developed in the United States, split epithelioid mesotheliomas into three prognostic groups with marked differences in survival. Now, this three-tiered nuclear grading system has been combined with the presence or absence of necrosis to form the currently recommended two-tiered grading system of low- and high-grade epithelioid mesothelioma. This review will focus on the development of this grading system in mesothelioma, the grading system's shortcomings, and the application of the grading system to cytology specimens and other extra-pleural sites. Lastly, this review will briefly discuss alternative grading systems and future considerations.

Guiding Irregular Nuclear Morphology on Nanopillar Arrays for Malignancy Differentiation in Tumor Cells

For more than a century, abnormal nuclei in tumor cells, presenting subnuclear invaginations and folds on the nuclear envelope, have been known to be associated with high malignancy and poor prognosis. However, current nuclear morphology analysis focuses on the features of the entire nucleus, overlooking the malignancy-related subnuclear features in nanometer scale. The main technical challenge is to probe such tiny and randomly distributed features inside cells. We here employ nanopillar arrays to guide subnuclear features into ordered patterns, enabling their quantification as a strong indicator of cell malignancy. Both breast and liver cancer cells were validated as well as the quantification of nuclear abnormality heterogeneity. The alterations of subnuclear patterns were also explored as effective readouts for drug treatment. We envision that this nanopillar-enabled quantification of subnuclear abnormal features in tumor cells opens a new angle in characterizing malignant cells and studying the unique nuclear biology in cancer.

Update on the pathologic diagnosis of malignant mesothelioma

Malignant mesothelioma is an uncommon tumor that may be difficult to diagnose. The International Mesothelioma Interest Group has been writing guidelines for pathological diagnosis that are periodically updated. The guidelines are being updated based on published literature in the last 3 years, and experience of more than 20 leading international pathologists in the field who will be co-authors. Updates were discussed by attendees of the Pulmonary Pathology Society Biennial Meeting (Dubrovnik, Croatia, June 2019). Areas with significant advancements/changes include utilization of immunohistochemistry (establishing mesothelial lineage and benign versus malignant), prognosis and nuclear grading, biphasic malignant mesothelioma, transitional pattern, malignant mesothelioma in situ, and therapeutic/molecular targets.

Mitosis count and number of cancer cells in cases of primary pulmonary adenocarcinoma: Correlations among phosphorylated histone 3, number of cancer cells, nuclear grade, pathologic features and prognosis

Immunohistochemistry findings for the phosphorylated form of histone 3 (pHH3) have been shown to be a reliable mitosis-specific marker. We evaluated the correlation between pHH3-stained mitotic figures (PHMFs) and clinical outcome, and compared the results with findings for numbers of PHMFs and cancer cells. The primary tumor was obtained from 113 patients with pulmonary adenocarcinomas (≤2 cm maximum dimension). All specimens were stained with pHH3, then the number of cancer cells in each was determined. Cases with a cancer-cell index ≥1000 showed worse recurrence-free survival as compared to those with a value <1000 (P < 0.001). Also, cases with a pHH3 index ≥0.27 showed worse recurrence-free survival as compared to <0.27 (P = 0.001) and cases with a pHH3/cancer-cell index ≥0.001 showed worse recurrence-free survival as compared to <0.001 (P = 0.002). Multivariate analysis demonstrated that pHH3/cancer-cell index was significantly correlated with prognosis, but not Ki-67 index. The number of cancer cells was also strongly correlated with progression of Noguchi's classification and WHO pathologic type. pHH3/cancer-cell index was correlated with prognosis, and those were useful for prognostic evaluation of pulmonary adenocarcinoma patients. Furthermore, cancer cell number was correlated with Noguchi's classification and WHO pathologic type.

Nuclear features in oral squamous cell carcinoma: A computer-assisted microscopic study

Background and Objectives:

Oral squamous cell carcinoma (OSCC) is one of the most common tobacco-related cancers affecting the Indian population. Various malignancy-grading systems based on different histopathological features have been proposed for OSCC. Due to inherent subjectivity, inter-observer variation and reproducibility of a grading system remains a problem. Grading systems based on nuclear morphometry have been proposed for laryngeal, renal and pharyngeal carcinomas. In this study, an attempt was made to grade oral OSCC based on computer-assisted microscopic evaluation of nuclear features. Our intention was also to evaluate the use of Feulgen stain for studying nuclear features.

Materials and Methods:

Sections made from buccal mucosa biopsies of normal mucosa as well as different grades OSCC were stained by Feulgen reaction. The nuclear features were evaluated by computer-assisted microscopic image analysis for nuclear area (NA), nuclear perimeter (NP) and nuclear form factor (NF) and correlated with histologic grading of OSCC. Nuclear shape, membrane outline, chromatin clumps, nucleoli, and abnormal mitoses were also evaluated.

Results:

NA and NP were observed to be significantly increased in OSCC (P < 0.001) when compared with the control group. These values increased in correlation with increasing grades of OSCC. However, NF was found to more in the control group (P < 0.001).

Conclusion:

It may be concluded from the results that computer-assisted nuclear morphometry is a reliable tool for grading OSCC. A new grading system based on nuclear features for OSCC has been proposed.