Unusual radiologic presentations of malignant peritoneal mesothelioma

Our plain-English summary of Unusual radiologic presentations of malignant peritoneal mesothelioma, by P.H. Sugarbaker, J.S. Jelinek (World Journal of Radiology, 2020).

The study

• Authors: P.H. Sugarbaker, J.S. Jelinek
• Journal: World Journal of Radiology
• Published: 2020;12(12):316-326
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Malignant peritoneal mesothelioma is an unusual disease process characterized radiologically by ascites and infiltration of the peritoneum by multiple small tumor nodules. Both parietal and visceral peritoneum are involved by the multiple malignant tumor nodules. Computed tomography (CT) has been used to identify the anatomic pathology induced by the progression of this malignant process.

Aim: To identify and then describe unusual CT images in patients with malignant peritoneal mesothelioma. Recognition of these unusual radiologic findings can cause the radiologist to be suspicious of this rare malignant process.

Methods: In 100 patients who were to undergo definitive treatment of malignant peritoneal mesothelioma, the findings on preoperative CT scans were catalogued. Many of these changes were repeatedly noted on the CT scans. Other pathologic CT images were less common. These unusual radiologic presentations were specially studied in this manuscript.

Results: Eight unusual radiologic presentations of malignant peritoneal mesothelioma were selected for study. These unusual findings included a mass occurring within a Spigelian hernia, infiltration of the splenic parenchyma by spherical mesothelioma masses, infiltration of the lower mediastinum by tumor, a mesothelioma mass within a left inguinal canal, enlarged cardiophrenic angle lymph nodes, pleural plaques associated with the progression of malignant peritoneal mesothelioma, splenic notches caused by disease surrounding the spleen, and a mass greater than 5 cm associated with the proximal jejunum and directly adjacent to the anatomic location of the Treitz ligament.

Conclusion: There are unusual radiologic presentations of malignant peritoneal mesothelioma that are important to recognize in order to accurately diagnose this disease by CT.

©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.

In plain English

This retrospective study, from MedStar Washington Hospital Center in Washington, DC, reviewed CT scans taken within 10 days before surgery in 100 patients with malignant peritoneal mesothelioma. The patients were to be treated with cytoreductive surgery and heated chemotherapy inside the abdomen (HIPEC). The authors picked eight uncommon CT findings and described one patient for each. Across all 100 patients, a mass larger than 5 cm next to the upper small bowel (proximal jejunum) was seen in 15%, enlarged cardiophrenic angle lymph nodes over 1.5 cm in 10%, and involvement of the lower mediastinum in 2%. A mass in a Spigelian hernia, a mass in the inguinal canal, masses invading the spleen, pleural plaques, and splenic notches were each seen in one patient. The one patient with pleural plaques had known past asbestos exposure, and the plaques did not progress to pleural mesothelioma. Six of the other seven described patients were reported to have no history of asbestos exposure. The authors concluded that these unusual CT presentations need to be recognized to diagnose the disease accurately by CT. Some details in the article conflict with each other.

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 preoperative CT scans, with individual case descriptions of eight patients showing unusual findings
• Who was studied: 100 patients with biopsy-confirmed malignant peritoneal mesothelioma who were to undergo cytoreductive surgery and HIPEC at MedStar Washington Hospital Center, Washington, DC, each with CT within 10 days before surgery. The eight described patients were aged 31 to 73, two women and six men. No overall study dates are given.
• Exposure: Asbestos exposure was not the subject of the study. Among the eight described patients, one (patient 6) had known prior asbestos exposure. Six were reported to have no history of asbestos exposure. Exposure history is not stated for patient 8. No fiber types are named.
• Main results:
  • Among the 100 patients, a mass greater than 5 cm immediately adjacent to the proximal jejunum was the most common of the unusual findings presented, at 15%.
  • Calcification was not seen in any of the 15 patients with a mass next to the jejunum.
  • Enlarged cardiophrenic angle lymph nodes greater than 1.5 cm were recorded in 10 of the 100 patients (10%).
  • Direct involvement of the lower mediastinum was seen in 2 of the 100 patients (2%).
  • Masses invading the spleen were seen in one of the 100 patients. In the incidence section, 4 other patients had intraabdominal masses larger than 5 cm, giving 5%.
  • A mass in a Spigelian hernia was seen in a single patient among the 100.
  • A mesothelioma mass in an inguinal hernia was seen in a single patient among the 100.
  • Pleural plaques were seen in one of the 100 patients, and splenic notches in one.
  • In the patient with pleural plaques (patient 6, a 56-year-old man with known asbestos exposure), the plaques did not progress to pleural mesothelioma. He survived 7 years and 8 months after treatment.
• The authors' conclusion: The authors concluded that there are unusual radiologic presentations of malignant peritoneal mesothelioma that need to be recognized to diagnose the disease accurately by CT. They also wrote that a mass next to the jejunum is not described in peritoneal metastases from other cancers such as appendix, colon or ovarian cancer.
• Limitations the authors state:
  • The authors state that it has not been determined whether cancer is present in enlarged cardiophrenic lymph nodes of 1.5 cm or more. In patient 5 these nodes were not removed.
  • For the patients with lower mediastinal masses, the authors state they cannot determine whether the disease spread from the peritoneum or began in both the pericardium and peritoneum.

Topics

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Ascites, Peritoneum, Pathology, CT Scan, Parenchyma, Mesothelioma, Mediastinum.

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