Accuracy of pleural biopsy for the diagnosis of histologic subtype of malignant pleural mesothelioma: Necropsy-based study of 134 cases

Our plain-English summary of Accuracy of pleural biopsy for the diagnosis of histologic subtype of malignant pleural mesothelioma: Necropsy-based study of 134 cases, by P.G. Barbieri, D. Consonni, M. Schneider (Tumori, 2022).

The study

• Authors: P.G. Barbieri, D. Consonni, M. Schneider
• Journal: Tumori
• Published: 2022;108(1):26-32
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Definition of histologic subtype of malignant pleural mesothelioma (MPM) is important for management of patients, because surgical treatment improves prognosis for patients with epithelioid but not biphasic or sarcomatoid MPM. In a series of necropsies performed in a hospital specialized for MPM diagnosis, we retrospectively investigated the accuracy of histologic diagnosis performed on pathologic specimens collected through pleural biopsies obtained at video-assisted thoracoscopic surgery (VATS) or surgery.

Methods: We reviewed histologic records of an unselected series of autopsies performed in patients with MPM employed in the Monfalcone shipyards (Northeast Italy) or living with shipyard workers from 1999 through 2017. Using necropsy results as a gold standard, we calculated sensitivity, specificity, and positive and negative predictive values of histology from VATS or surgery after combining nonepithelioid subtypes.

Results: We retrieved necropsy records for 134 patients: 62 (46.3%) with epithelioid, 51 (38.1%) with biphasic, and 21 (15.7%) with sarcomatoid MPM. We observed good sensitivity of VATS (0.94) and surgery (0.89) in diagnosing epithelioid MPM. Conversely, specificity was low (VATS: 0.46; surgery: 0.32). Therefore, positive predictive values were also low (VATS: 0.58; surgery: 0.60). Misclassification was particularly high for biphasic MPM (three-fourths of biphasic MPM at necropsy had been classified as epithelioid at VATS or surgery).

Conclusions: We observed a substantial degree of misclassification between epithelioid and biphasic MPM for pleural biopsies performed during VATS. Our results suggest caution should be taken in using histologic subtype obtained from VATS in selecting patients with MPM for surgical treatment. We also observed substantial misclassification of biospecimens collected during MPM surgery.

In plain English

This retrospective study used autopsy findings as the standard to judge how accurately biopsies taken in life had subtyped malignant pleural mesothelioma. The 134 autopsied people (Italy, 1999 to 2017) were Monfalcone shipyard workers or lived with shipyard workers, and had been exposed to asbestos. At autopsy, 62 were epithelioid, 51 biphasic and 21 sarcomatoid. Biopsies at video-assisted thoracoscopic surgery (VATS) distinguished epithelioid from nonepithelioid tumors with sensitivity 0.94 (95% CI 0.82 to 0.99) but specificity 0.46 (95% CI 0.33 to 0.59). Of 42 biphasic tumors at autopsy, 32 (76%) were called epithelioid at VATS. Open-surgery biopsies had a sensitivity of 0.89 (95% CI 0.73 to 0.97) and specificity of 0.32 (interval 0.17 to 0.51). Of 24 biphasic tumors, 18 (75%) had been called epithelioid. Median survival by autopsy subtype was 11 months (95% CI 8 to 14) for biphasic and 6 months (4 to 9) for sarcomatoid. The authors concluded that caution is needed in using VATS subtype to select patients for surgery. The cases were not reviewed by an independent pathology panel.

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 study of diagnostic accuracy, comparing histologic subtype on biopsies taken during life (VATS or open surgery) with subtype at necropsy, used as the gold standard
• Who was studied: 134 people with malignant pleural mesothelioma confirmed by histology during life (124 men, 10 women), autopsied 1999 through 2017. They were employed in the Monfalcone shipyards (northeast Italy) or lived with shipyard workers. Two of 136 eligible cases were excluded because the subtype was unspecified.
• Exposure: Previous asbestos exposure as shipyard workers or their family members; no fiber types or doses are given
• Main results:
  • At necropsy, 62 of 134 patients (46.3%) had epithelioid, 51 (38.1%) biphasic and 21 (15.7%) sarcomatoid mesothelioma
  • VATS biopsies (106 patients): sensitivity for epithelioid versus combined biphasic and sarcomatoid mesothelioma was 0.94 (44/47; 95% CI 0.82 to 0.99)
  • VATS biopsies: specificity was 0.46 (27/59; 95% CI 0.33 to 0.59)
  • Of 42 biphasic cases at necropsy, 32 (76%) had been classified as epithelioid on VATS biopsies
  • Surgical biopsies (66 patients): sensitivity for epithelioid versus nonepithelioid mesothelioma was 0.89 (31/35; 95% CI 0.73 to 0.97)
  • Surgical biopsies: specificity was 0.32 (10/31; interval 0.17 to 0.51, printed as a 96% CI)
  • Of 24 biphasic cases at necropsy, 18 (75%) had been classified as epithelioid on surgical biopsies
  • Among 38 patients with both VATS and surgical biopsies, agreement between the two was very good (Cohen kappa 0.83, 95% CI 0.80 to 0.93)
  • By subtype at necropsy, median survival was 17 months (95% CI 12 to 22) for epithelioid, 11 months (95% CI 8 to 14) for biphasic and 6 months (95% CI 4 to 9) for sarcomatoid mesothelioma
  • The authors reported that misclassification was not associated with chemotherapy, radiotherapy or talc pleurodesis
• The authors' conclusion: The authors concluded that there was substantial misclassification between epithelioid and biphasic mesothelioma on VATS biopsies, and that caution should be taken in using VATS subtype to select patients for surgery. They also found substantial misclassification on surgical specimens.
• Limitations the authors state:
  • Cases were not reviewed by an independent panel of pathologists; diagnoses were taken from the records
  • Records were collected retrospectively, so there was no information on the amount of tissue or the number of biopsies taken
  • The finding on sarcomatoid misclassification at surgery was based on few cases

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Biopsy, Histological Subtype, Pleural Mesothelioma, Autopsy, Prognosis, Epithelioid, Biphasic Mesothelioma, Sarcomatoid.

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• Therapeutic outcome according to histologic subtype in 121 patients with malignant pleural mesothelioma — G.L. Ceresoli, L.D. Locati, et al. (2001)
• The differential diagnosis between pleural sarcomatoid mesothelioma and spindle cell/pleomorphic (sarcomatoid) carcinomas of the lung: evidence-based guidelines from the International Mesothelioma Panel and the MESOPATH National Reference Center — A.M. Marchevsky, N. LeStang, et al. (2017)
• Diagnosis of lung cancer: a necropsy-based study of 128 cases (1997-2016) — P.G. Barbieri, D. Mirabelli (2021)
• Diffusion-weighted MRI of malignant pleural mesothelioma: preliminary assessment of apparent diffusion coefficient in histologic subtypes — R.R. Gill, S. Umeoka, et al. (2010)

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