The World Health Organization Reporting System for Lung Cytopathology

Abstract

The International Academy of Cytology has joined with the International Agency for Research on Cancer (IARC) to bring together a group of experts in lung cytopathology to develop a WHO Reporting System for Lung Cytopathology (WHO System). This WHO System defines five categories for reporting lung cytopathology, that is, “Insufficient”/“Inadequate”/“Non-diagnostic,” “Benign,” “Atypical,” “Suspicious for malignancy,” and “Malignant,” each with a clear descriptive term for the category, a definition, a risk of malignancy and a suggested management algorithm. The key diagnostic cytopathology features of each of the lesions within each category have been established by consensus and will be presented more fully in a subsequent IARC e-book and published hard cover book.The WHO System provides the best practice application of ancillary testing, including immunocytochemistry and molecular pathology, and provides a review to guide sampling and processing techniques to optimize the handling and preparation of the cytopathology sample emphasizing the cytomorphological differential diagnosis to aid low-resourced settings. The authors recognize that local medical and pathology resources will vary, particularly in low- and middle-income countries, and have developed the WHO System to make it applicable worldwide based on cytomorphology with options for further diagnostic management of the patient.The online WHO System provides a direct link to the WHO Tumour Classification for Thoracic Tumours 5th Edition. It will raise the profile and use of cytopathology by increasing awareness of its current role and its potential role in the era of personalized medicine based on molecular pathology utilizing “small biopsies.” Ultimately, the System will improve patient care and outcomes.This System aims to improve and standardize the reporting of cytopathology, facilitate communication between cytopathologists and clinicians and improve patient care. The System is based on the current role of lung cytopathology and synthesizes the existing evidence while highlighting areas requiring further research and the future potential role of lung cytopathology.

A Comprehensive Review of the Newest World Health Organization (WHO) Cytopathology Reporting Systems

“…5 They provide diagnostic management alternatives that recognize the different prognostic and auxiliary diagnostic testing modalities like immunocytochemistry (ICC), in situ hybridization, and molecular techniques available in low-income and middle-income countries. 5 In 2016, the Papanicolaou Society of Cytopathology proposed Standardized Terminology and Nomenclature for Respiratory Cytology in 6 categories: Nondiagnostic, Negative for malignancy, Atypical, Neoplastic (a) Benign (b) Neoplasm-low-grade carcinoma, Suspicious for malignancy and Malignant. 6 The WHO System-Lung Cytopathology (2022) system has limited it to 5 categories: Insufficient/Inadequate/Nondiagnostic, Benign, Atypical, Suspicious for malignancy, and Malignancy which can be stratified by their ROM.…”

“…The specimens for respiratory cytology commonly includes FNAB, bronchial wash(BW), bronchial brushing(BB), bronchoalveolar lavage, and sputum. 5,7 WHO also encourages the application of ROSE, which entails 4 steps: smear preparation, staining, interpretation, and sample triage. 7,8 In cell preparation methods, they recommend cell block preparation for ancillary diagnostic testing and cell culture for better and personalized drug treatment.…”

“…5,7 Any specimen material that shows a pathologic process consistent with the clinical and imaging findings may be classified into a category other than Insufficient/Inadequate/Nondiagnostic. 5,7 Different lung cytology specimen types have specific characteristics to determine adequacy; however, none of them require a particular quantity of cells or cell types (Table 1). 5,7 Insufficient/Inadequate/Nondiagnostic A specimen categorized as "Insufficient/Inadequate/ Nondiagnostic" lacks sufficient material in quantity or quality for a reliable diagnosis.…”

“…5,7 Different lung cytology specimen types have specific characteristics to determine adequacy; however, none of them require a particular quantity of cells or cell types (Table 1). 5,7 Insufficient/Inadequate/Nondiagnostic A specimen categorized as "Insufficient/Inadequate/ Nondiagnostic" lacks sufficient material in quantity or quality for a reliable diagnosis. 5,7 When the cytopathology material contains no diagnostic material that may explain the imaging results or clinical complaints, a specimen is labeled as "Insufficient/Inadequate/Nondiagnostic."…”

“…5,7 Insufficient/Inadequate/Nondiagnostic A specimen categorized as "Insufficient/Inadequate/ Nondiagnostic" lacks sufficient material in quantity or quality for a reliable diagnosis. 5,7 When the cytopathology material contains no diagnostic material that may explain the imaging results or clinical complaints, a specimen is labeled as "Insufficient/Inadequate/Nondiagnostic." 7 A cytopathologist or organization should decide on 1 nomenclature and adhere to it.…”