Pathology of mesothelioma

Our plain-English summary of Pathology of mesothelioma, by K. Inai (Environmental Health and Preventive Medicine, 2008).

The study

• Author: K. Inai
• Journal: Environmental Health and Preventive Medicine
• Published: 2008;13(2):60-4
• Cited by: 52 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The incidence of mesothelioma has been gradually increasing in Japan, and the underlying factor for this is considered to be the increase in the amount of asbestos imported into Japan between 1960 and 1975. Mesothelioma can be roughly divided into localized and diffuse types, but the former is extremely rare. In making a diagnosis of mesothelioma, it is important to confirm the location of tumor and the specific gross findings before histological examination. Mesothelioma can be categorized histologically as epithelioid type, sarcomatoid type, biphasic type, desmoplastic type, among others. It can take many forms; consequently, there are many diseases to be differentiated when the diagnosis of mesothelioma is based on histological analyses. Immunohistochemical stains are useful for making a diagnosis, but the correct combination of antibodies as positive or negative markers should be selected and a comprehensive assessment of the staining results is necessary. The accuracy of the pathological diagnosis is very important to the patients because they can be receive official compensation or relief when the diagnosis of mesothelioma is confirmed. Under present conditions, both clinicians and pathologists must make a concerted effort to improve the accuracy of the diagnosis of mesothelioma.

In plain English

This article was a narrative review of the pathology and diagnosis of mesothelioma. It did not report a new study of patients. Citing official Japanese government data, the author reported that mesothelioma deaths in Japan rose from 500 in 1995 to 953 in 2004. The author linked this rise to asbestos imported into Japan between 1960 and 1975, given a latent period of about 40 years. Citing a report on 878 deaths in 2003, the author gave a male-to-female ratio of almost 3 to 1, with tumors in the pleura in 84%, the peritoneum in 12% and the pericardium in 1%. Citing other work, the author described epithelioid, sarcomatoid and biphasic types as roughly 60, 20 and 20% of cases. The review listed diseases that can resemble mesothelioma and the antibody stains used to tell them apart, noting that no single antibody is completely specific. The author roughly estimated that 10 to 15% of mesothelioma patients receive an inadequate diagnosis. The author concluded that clinicians and pathologists must work to improve diagnostic accuracy.

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: Narrative review (special feature article) of mesothelioma pathology, histological types, differential diagnosis and immunohistochemistry; no original study data
• Who was studied: No study population. The review cites Japanese national data on mesothelioma deaths (500 in 1995, 953 in 2004) and a report on 878 people who officially died from mesothelioma in Japan in 2003
• Exposure: Asbestos in general (no fiber types named). The rise in deaths is described as paralleling asbestos imports into Japan between 1960 and 1975, with a latent period of about 40 years
• Main results:
  • According to official Ministry of Health, Labor and Welfare data cited by the author, mesothelioma deaths in Japan were 500 in 1995 and 953 in 2004
  • Among the 878 people who officially died from mesothelioma in Japan in 2003 (data from a cited report), the male:female ratio was almost 3:1. The tumor was in the pleura in 84%, the peritoneum in 12% and the pericardium in 1%, with no cases in the tunica vaginalis
  • The same 2003 data put tumor location at 84% pleura, 12% peritoneum and 1% pericardium
  • Citing other work, the author gave the proportions of the three major histological types (epithelioid, sarcomatoid, biphasic) as approximately 60, 20 and 20%. The desmoplastic type was described as rare (probably 1 to 2%)
  • Most tumors formerly called localized mesothelioma are now diagnosed as solitary fibrous tumor. The author described this as a separate entity with no relation to asbestos exposure
  • No antibody is completely specific for mesothelioma, so a combination of positive and negative markers and an overall assessment of the results is needed
  • Sarcomatoid carcinoma of the lung and sarcomatoid pleural mesothelioma both stain positive for cytokeratin. The author therefore stated that gross findings or imaging are very important in telling them apart
  • The author gave a rough estimate that approximately 10 to 15% of mesothelioma patients receive an inadequate diagnosis
  • In the committee judging patients' relief, 30% of applicants were judged as not having mesothelioma or had the decision deferred until more evidence was provided
• The authors' conclusion: The author concluded that Japanese clinicians and pathologists must make an effort to improve the accuracy of mesothelioma diagnosis, and that pathologists in particular should use adequate immunohistochemical stains
• Limitations the authors state:
  • The author noted that the proportion of each histological type varies among reports because of the variety of histological analyses used
  • The author noted that very few early-stage peritoneal mesotheliomas have been reported, so little is known about the early stage of that disease

Topics

Medical terms in this study, explained in our Lexicon: Pathology, Mesothelioma, Epithelioid, Sarcomatoid, Biphasic Mesothelioma, Desmoplastic Mesothelioma.

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