What's new in neoplastic pulmonary pathology 2026: updates on grading, staging and molecular testing

Our plain-English summary of What's new in neoplastic pulmonary pathology 2026: updates on grading, staging and molecular testing, by A. Tiefenbacher, L. Brčić (Journal of Pathology and Translational Medicine, 2026).

The study

• Authors: A. Tiefenbacher, L. Brčić
• Journal: Journal of Pathology and Translational Medicine
• Published: 2026;60(5):587-591
• Read it: PubMed · Publisher · Free full text

Abstract

Neoplastic pulmonary pathology has continued to advance in recent years, including the introduction of histologic grading systems for both adenocarcinoma and squamous cell carcinoma, implementation of the UICC TNM 9th Edition classification, expanded molecular testing requirements, refinements in neuroendocrine tumor classification, and improvements in mesothelioma diagnostics. This newsletter summarizes the most important developments relevant to practicing pathologists.

In plain English

This article was a newsletter, not an original study. The authors summarized recent developments in the pathology of lung tumors and pleural mesothelioma for practicing pathologists, drawing on published work by others. It reported no new patient data and did not discuss asbestos. The only exposure it mentioned was smoking, in describing certain rare lung tumors. For lung cancer, it described grading systems for resected adenocarcinoma and squamous cell carcinoma, changes in the 9th edition of TNM staging, and expanded molecular testing. For pleural mesothelioma, it stated that tumor cells must be confirmed as mesothelial with at least two positive markers. It also reported that a cited study had validated a panel of BAP1, MTAP, Merlin and p53 stains for telling mesothelioma apart from benign mesothelial growths. It described a two-tier grading system for epithelioid mesothelioma and a newly proposed low-grade form of mesothelioma in carriers of inherited BAP1 mutations. It also described mesothelioma in situ, an early non-invasive form with fewer than 50 reported cases, which the article said carries a high risk of progression to invasive mesothelioma.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Newsletter (narrative summary of recent developments and published literature); no original data
• Who was studied: No study population; the article summarized published studies and classification updates on lung tumors and pleural mesothelioma
• Exposure: Asbestos is not discussed. Smoking is mentioned only in describing tumor types: smoking history as a feature of thoracic SMARCA4-deficient undifferentiated tumor, and an atypical small cell lung cancer described in never/light smokers
• Main results:
  • The article stated that the mesothelial origin of tumor cells must always be confirmed with at least two positive mesothelial markers
  • The article reported that a combined panel of BAP1, MTAP, Merlin and p53 immunohistochemistry has been validated (citing a published study) for distinguishing mesothelioma from benign mesothelial proliferations
  • The article stated that BAP1 loss on immunohistochemistry has moderate sensitivity and near 100% specificity for mesothelioma
  • The article stated that diffuse mutant-pattern p53 staining is infrequent in mesothelioma (approximately 7%)
  • The article stated that GATA3 expression has been reported in approximately 70% of sarcomatoid mesotheliomas (citing a published study)
  • The article described grading of epithelioid mesothelioma as a two-tier system based on nuclear grade and mitotic count
  • The article described low-grade germline-mutant BAP1-associated mesothelioma (L-BAM) as having a more indolent course than sporadic mesothelioma but ultimately progressing to lethal disease
  • The article stated that reported cases of mesothelioma in situ remain rare (fewer than 50) and that it carries a high risk of progression to invasive mesothelioma
  • The article described the IASLC grading of resected lung adenocarcinoma, in which any tumor with 20% or more high-grade patterns is grade 3
  • The article reported that the 9th edition of TNM staging for lung carcinoma took effect January 1, 2025, with changes to the N and M descriptors
• The authors' conclusion: The article has no separate conclusion section; it presents itself as a summary of recent developments for practicing pathologists

Topics

Medical terms in this study, explained in our Lexicon: Pathology, Staging, Molecular Profiling, Adenocarcinoma, Squamous Cell Carcinoma, UICC, Mesothelioma.

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