Histological typing of lung tumours

Our plain-English summary of Histological typing of lung tumours (Tumori, 1981).

The study

• Journal: Tumori
• Published: 1981;67(4):253-72
• Cited by: 73 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The WHO Histological classification of Lung Tumours, published in 1967, has been revised. The main features are as follows: Squamous cell carcinoma (epidermoid carcinoma) has the same definition as in the original version, i.e., the identification of keratin and/or intercellular bridges by light microscopy. Three degrees of histological differentiation are described. Dysplasia and carcinoma in situ are discussed. Small cell carcinoma is divided into oat-cell carcinoma, an intermediate cell type and a category for oat-cell carcinomas combined with other major types. Adenocarcinoma includes the acinar, papillary and bronchiolo-alveolar forms and the solid carcinomas with mucus formation (previously part of the large cell carcinoma group). Mesothelial tumours are divided into fibrous, epithelial and biphasic subtypes. A number of less common tumours and tumour-like lesions are defined.

In plain English

This article is not a study of patients or of asbestos exposure. It is the second edition of the World Health Organization's system for naming and classifying lung tumours by their appearance under the microscope, revising the 1967 version. The revision was drawn up at a WHO meeting of pathologists in Geneva, 24 to 28 October 1977, after a 1977 consultation on criticisms of the earlier version. The document defined most tumour types, referred readers to a separate WHO classification for soft tissue tumours, and stated that tumours should be typed by light microscopy. Small cell carcinoma was divided into oat cell carcinoma, an intermediate cell type and combined oat cell carcinoma, and squamous cell carcinoma was given three grades of differentiation. Mesothelial tumours, described as tumours of the lining of the pleura, were split into benign and malignant mesothelioma, with malignant forms classed as epithelial, fibrous (spindle-cell) or biphasic. The document noted that epithelial mesothelioma can be difficult to tell apart from adenocarcinoma. In one sentence, without presenting data, it stated that diffuse mesothelioma is associated with exposure to asbestos, particularly the blue form (crocidolite).

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: Consensus classification document: the revised (second edition) WHO histological classification of lung tumours, with definitions and explanatory notes. It is not an original study.
• Who was studied: No study population. The classification was prepared by pathologists convened by WHO. It followed a 1977 consultation and was worked out at a WHO meeting in Geneva, 24 to 28 October 1977.
• Exposure: Asbestos is mentioned only once, as a background statement without data: diffuse mesothelioma is associated with asbestos exposure, particularly the blue form (crocidolite).
• Main results:
  • Mesothelial tumours were divided into fibrous, epithelial and biphasic subtypes.
  • Mesothelial tumours were defined as tumours of the mesothelial lining of the pleura.
  • Diffuse mesotheliomas of the pleura were described as malignant, involving both the parietal and visceral surfaces.
  • Benign mesotheliomas were described as localized and often pedunculated (attached by a stalk).
  • The document noted difficulty in distinguishing epithelial mesotheliomas from adenocarcinomas. It stated that intracellular epithelial mucin, particularly as globules, indicates adenocarcinoma.
  • Small cell carcinoma was divided into oat cell carcinoma, an intermediate cell type, and oat cell carcinomas combined with other major types.
  • Squamous cell carcinoma may be graded into three degrees of differentiation.
  • Tumour type is to be assigned on the basis of light microscopy, even when electron microscopy gives further information.
  • Soft tissue tumours of the lung were not defined in this document. Readers were referred to the separate WHO Histological Typing of Soft Tissue Tumours.
• The authors' conclusion: The document draws no conclusions of its own. It presents the classification, definitions and explanatory notes that the 1977 WHO meeting formulated and recommended for publication.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer.

Medical terms in this study, explained in our Lexicon: Histological Subtype, Squamous Cell Carcinoma, Carcinoma, Adenocarcinoma, Acinar, Biphasic Mesothelioma.

Related studies

• An attempt to use the WHO typing in the histological classification of lung carcinomas — A. Reinilä, K. Dammert (1974)
• Histologic typing of lung cancer in Louisiana — H. Rothschild, H. Buechner, et al. (1982)
• Tests for effect of asbestos on benzo[a]pyrene carcinogenesis in the respiratory tract — L. Miller, W.E. Smith, et al. (1965)
• Phosphatide composition of normal, hyperplastic and malignant squamous epithelium — C. Carruthers (1966)
• Use of antibodies to carcinoembryonic antigen and human milk fat globule to distinguish carcinoma, mesothelioma, and reactive mesothelium — R.J. Marshall, A. Herbert, et al. (1984)
• Lung cancer risk among bricklayers in a pooled analysis of case-control studies — D. Consonni, S. De Matteis, et al. (2015)

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