Malignant Pleural Mesothelioma: Are There Imaging Characteristics Associated With Different Histologic Subtypes on Computed Tomography?

Our plain-English summary of Malignant Pleural Mesothelioma: Are There Imaging Characteristics Associated With Different Histologic Subtypes on Computed Tomography?, by J.G. Escalon, K.A. Harrington, A.J. Plodkowski, et al (Journal of Computer Assisted Tomography, 2018).

The study

• Authors: J.G. Escalon, K.A. Harrington, A.J. Plodkowski, J. Zheng, M. Capanu, M.G. Zauderer, V.W. Rusch, M.S. Ginsberg
• Journal: Journal of Computer Assisted Tomography
• Published: 2018;42(4):601-606
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Determine imaging characteristics specific to epithelioid (eMPM), sarcomatoid (sMPM), and biphasic (bMPM) subtypes of malignant pleural mesothelioma (MPM) on computed tomography.

Methods: Preoperative computed tomography scans of patients with MPM were retrospectively assessed for numerous features including primary affected side, volume loss, pleural thickness, pleural calcifications, pleural effusion, and lymphadenopathy.

Results: One hundred twenty-five patients with MPM were included. Histologic subdivision was 97 eMPM (77%), 17 bMPM (14%), and 11 sMPM (9%). Nonepithelioid MPM (bMPM and sMPM) was more likely than eMPM to have calcified pleural plaques (P = 0.035). Analyzed separately, bMPM and sMPM each demonstrated calcified plaques more frequently than eMPM, and sMPM more often had internal mammary nodes; however, P values did not reach significance (P = 0.075 and 0.071, respectively).

Conclusions: Calcified plaques are significantly more common in nonepithelioid subtypes compared with eMPM. Given the different prognoses and management of MPM subtypes, accurate noninvasive subtype classification is clinically vital.

In plain English

This retrospective study from Memorial Sloan Kettering Cancer Center in New York asked whether CT scans taken before surgery could tell apart the three tissue subtypes of malignant pleural mesothelioma: epithelioid, biphasic and sarcomatoid. The authors reviewed scans of 125 patients diagnosed between 2005 and 2015 whose subtype came from surgical tissue: 97 epithelioid, 17 biphasic and 11 sarcomatoid. Asbestos exposure was not studied. The thickness, location and appearance of pleural thickening did not differ significantly between subtypes. Calcified pleural plaques were seen in 24 of 97 epithelioid, 7 of 17 biphasic and 6 of 11 sarcomatoid cases (P = 0.075, not significant). When biphasic and sarcomatoid cases were grouped together as nonepithelioid, they were more likely than epithelioid cases to have calcified plaques (P = 0.035). After accounting for clinical stage, local invasion was seen in 20 of 28 nonepithelioid and 50 of 97 epithelioid cases (P = 0.045). The authors concluded that these features are more common in nonepithelioid subtypes. They noted that the study was retrospective and small, and that its results need cautious interpretation and confirmation.

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 comparing CT imaging features across histologic subtypes of malignant pleural mesothelioma
• Who was studied: 125 patients with malignant pleural mesothelioma (99 men, 26 women; mean age 69) at Memorial Sloan Kettering Cancer Center, New York. All had resection or open pleural biopsy, were diagnosed January 2005 to October 2015, and had a contrast-enhanced CT within 90 days of surgery. Of these, 97 were epithelioid, 17 biphasic and 11 sarcomatoid. Starting from 289 patients, 164 were excluded, including 55 with prior talc pleurodesis.
• Exposure: No asbestos or other exposure was studied. The study compared CT findings between histologic subtypes of the tumor.
• Main results:
  • There was no significant difference between the three subtypes in the degree, location or appearance of pleural thickening on CT.
  • Calcified pleural plaques were seen in 24 of 97 (25%) epithelioid, 7 of 17 (41%) biphasic and 6 of 11 (55%) sarcomatoid cases. The three-group comparison was not statistically significant (P = 0.075).
  • Internal mammary nodes were seen in 21 of 97 (22%) epithelioid, 4 of 17 (24%) biphasic and 6 of 11 (55%) sarcomatoid cases. The three-group comparison was not statistically significant (P = 0.071).
  • Biphasic and sarcomatoid cases combined (nonepithelioid) were more likely than epithelioid cases to have calcified plaques (P = 0.035).
  • In the analysis stratified by clinical stage, calcified plaques were present in 13 of 28 (46%) nonepithelioid cases compared with 24 of 97 (25%) epithelioid cases (P = 0.058).
  • In the analysis stratified by clinical stage, local invasion was present in 20 of 28 (71%) nonepithelioid cases compared with 50 of 97 (52%) epithelioid cases (P = 0.045).
• The authors' conclusion: The authors concluded that calcified pleural plaques and local invasion are more common in nonepithelioid subtypes of malignant pleural mesothelioma than in the epithelioid subtype. They added that larger studies may be useful to confirm whether CT can distinguish these subtypes.
• Limitations the authors state:
  • The study was retrospective and had a relatively small sample size.
  • There were relatively few nonepithelioid cases.
  • No correction was made for multiple testing, so the authors said the results should be interpreted with caution and validated in future studies.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Histological Subtype, Epithelioid, Sarcomatoid, Biphasic Mesothelioma, Pleural Thickness, Pleural Calcification, Pleural Effusion.

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• Diagnostic Value of Computed Tomography Imaging Features in Malignant Pleural Mesothelioma — M. Fortin, E. Cabon, et al. (2020)
• 18F-fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography fused imaging in malignant mesothelioma patients: looking from outside is not enough — E. Roca, S. Laroumagne, et al. (2013)
• Computed tomography findings in 66 patients with malignant pleural mesothelioma due to environmental exposure to asbestos — F. Okten, D. Köksal, et al. (2006)
• Fatal pleural mesothelioma in Japan (2003-2008): evaluation of computed tomography findings — K. Kato, K. Gemba, et al. (2016)

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