On the diagnosis of malignant pleural mesothelioma: A necropsy-based study of 171 cases (1997-2016)

Our plain-English summary of On the diagnosis of malignant pleural mesothelioma: A necropsy-based study of 171 cases (1997-2016), by P.G. Barbieri, D. Mirabelli, C. Magnani, et al (Tumori, 2019).

The study

• Authors: P.G. Barbieri, D. Mirabelli, C. Magnani, A. Brollo
• Journal: Tumori
• Published: 2019;105(4):304-311
• Type of article: Review
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Malignant pleural mesothelioma (MPM) diagnosis is known to be difficult. We report on the diagnostic elements available in life in an MPM necropsy case series and describe the frequency of non-neoplastic asbestos-related diseases as biological exposure indices.

Methods: We reviewed pathologic and clinical records of an unselected series of autopsies (1977-2016) in patients with MPM employed in the Monfalcone shipyards or living with shipyard workers. We assessed the consistency with autopsy results of diagnoses based on, respectively, radiologic, cytologic, and histologic findings, with and without immunophenotyping.

Results: Data on 171 cases were available: for 169, autopsy confirmed the MPM diagnosis. In life, 119 cases had histologic confirmation of diagnosis, whereas 7 were negative; all cases without immunophenotypization were autoptic MPMs. Cytology alone had been positive in 18 autoptic MPM cases, negative in 14. Radiologic imaging alone had been positive in another 16, negative in 11. In the 2 cases not confirmed at autopsy, MPM had been suspected by chest computed tomography only. Bilateral pleural plaques were found in 144 and histologic evidence of asbestosis in 62 cases.

Conclusions: Autopsies confirmed 169/171 cases, including cases that would not be considered as certain based on diagnosis in life. Radiologic imaging, cytologic examination of pleural effusions, or both combined had low sensitivity but high positive predictive value: when they are positive, proceeding to thoracoscopy should be justified. MPM has been correctly diagnosed even without immunohistochemistry. The prevalence of pleural plaques and asbestosis was high due to severity of asbestos exposures in these cases.

In plain English

The authors reviewed autopsy and clinical records of 171 people who died with diagnosed or suspected malignant pleural mesothelioma in hospitals in Monfalcone, Gorizia and Udine, Italy. All had worked at the Monfalcone shipyards or lived with a shipyard worker, and 93% were men. The study compared diagnoses made in life by CT, pleural fluid cytology or biopsy with autopsy findings. Autopsy confirmed mesothelioma in 169 cases (98.8%). One of the other two had pleural metastases from a kidney cancer. Biopsy identified 119 of 125 examined cases that autopsy later confirmed. CT and cytology missed many cases, but positive results were usually confirmed. All 119 biopsy diagnoses were confirmed, including 30 without immunohistochemistry (119 minus the 89 tested) and 6 where it was not considered consistent with mesothelioma. Twenty cases in which mesothelioma had been ruled out in life were found only at autopsy. Older patients were less often diagnosed by biopsy. Bilateral pleural plaques were found in 144 cases and asbestosis in 62. The authors concluded that experienced pathologists diagnosed mesothelioma correctly even without immunohistochemistry.

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: Retrospective review of an unselected autopsy case series, comparing diagnosis made in life with autopsy findings
• Who was studied: 171 decedents autopsied in hospitals of Monfalcone, Gorizia and Udine (Italy) between 1997 and 2016, with malignant pleural mesothelioma diagnosed or suspected in life. All were employed at the Monfalcone shipyards or were relatives of shipyard workers. 159 were men (93.0%) and 12 were women; 40 (23.4%) were aged 80 or more at death.
• Exposure: Asbestos exposure, mainly occupational in the Monfalcone shipyards. 163 cases were classed occupational-certain, 3 occupational-probable and 5 nonoccupational-domestic (they lived with asbestos-exposed shipyard workers). Fiber types are not specified.
• Main results:
  • Autopsy established malignant pleural mesothelioma in 169 of 171 cases (98.8%) and ruled it out in 2. One of the two had pleural metastases from a renal carcinoma; the other had bilateral, non-neoplastic pleural thickenings.
  • Biopsy samples from 126 cases were examined: 119 favored mesothelioma and 7 were against it. Of those 7, 6 were later confirmed as mesothelioma at autopsy. Biopsy histology therefore identified 119 of 125 autopsy-confirmed cases (sensitivity 95.2%, CI 91.5–98.9).
  • Of the 119 cases with histologic confirmation in life, 89 had immunohistochemistry, considered consistent with mesothelioma in 83 but not in 6. The remaining 30 (worked out as 119 minus 89) had no immunohistochemistry. All 119 were confirmed at autopsy. Table 3 groups these as 83 'histology and immunohistochemistry' and 36 'histology, without immunohistochemistry', which apparently counts the 6 discordant cases with the 30 untested ones.
  • Histologic confirmation in life was not associated with sex (OR 1.7 for men, CI 0.5–5.7) but was associated with age. Compared with those under 60, the OR was 0.05 (CI 0.0–0.6) at 80 or more, with a highly significant trend. Lack of histologic evidence reached 27.9% of cases at age 70–79 and 62.5% at 80 or more.
  • Cytology of pleural effusions correctly identified 47 of 74 mesothelioma cases (sensitivity printed as 63.5, CI 54.3–76.3). All cases whose diagnosis rested on cytology were found to have mesothelioma at autopsy.
  • Chest CT sensitivity was limited (59%, CI 41%–78%). When CT was positive, autopsy found mesothelioma in 89% of cases (CI 74%–100%).
  • The authors stated that all cases where a mesothelioma diagnosis had been made in the absence of immunohistochemistry were confirmed at autopsy. The statement comes from their paragraph on histologic diagnosis; 2 of 15 diagnoses based on imaging alone were not confirmed.
  • Sensitivity of diagnosis in life was 88.1% (CI 83.3–93.0) when all types of evidence were combined. It was 70.4% (CI 63.5–77.2) if only histology was accepted, and 49.1% (CI 41.6–56.7) if immunohistochemistry was also required.
  • In 20 cases (12% of the series), mesothelioma had been ruled out in life and was diagnosed only at autopsy.
  • At autopsy, bilateral pleural plaques were seen in 144 cases (83% in the text, 84.2% in Table 1) and histologic asbestosis in 62 (36%). Asbestosis had been diagnosed in life in just 3.
  • Of the 169 autopsy-confirmed cases, survival was known for 165: 42% survived at least 1 year after diagnosis and 22% at least 2 years.
• The authors' conclusion: The authors concluded that autopsies confirmed 169 of 171 cases, including cases not considered certain from the diagnosis in life. They stated that when imaging and/or cytology are positive, the need for thoracoscopy should be carefully assessed. They also concluded that experienced pathologists correctly diagnosed mesothelioma even without immunohistochemistry.
• Limitations the authors state:
  • The authors noted that the low share of household exposures may be partly because autopsies were not carried out systematically in women living with shipyard workers.
  • Cytology was performed relatively infrequently: only 18 cases had a cytologic basis of diagnosis.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Autopsy, Cytology, Bilateral, Pleural Plaques, Pleural Effusion, Thoracoscopy, Immunohistochemistry.

Related studies

• Diagnosis of lung cancer: a necropsy-based study of 128 cases (1997-2016) — P.G. Barbieri, D. Mirabelli (2021)
• Pleural plaques and exposure to mineral fibres in a male urban necropsy population — A. Karjalainen, P.J. Karhunen, et al. (1994)
• Asbestos bodies and pleural plaques in human lungs at necropsy — I. Hägerstrand, B. Seifert (1973)
• Accuracy of pleural biopsy for the diagnosis of histologic subtype of malignant pleural mesothelioma: Necropsy-based study of 134 cases — P.G. Barbieri, D. Consonni, et al. (2022)
• Pleural plaques as risk indicators for malignant pleural mesothelioma: a necropsy-based study — C. Bianchi, A. Brollo, et al. (1997)
• Relationship between pleural plaques and biomarkers of cumulative asbestos dose. A necropsy study — P.G. Barbieri, D. Consonni, et al. (2019)

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