Well-differentiated papillary mesothelioma: A 17-year single institution experience with a series of 75 cases

Our plain-English summary of Well-differentiated papillary mesothelioma: A 17-year single institution experience with a series of 75 cases, by M. Sun, L. Zhao, I. Weng Lao, et al (Annals of Diagnostic Pathology, 2019).

The study

• Authors: M. Sun, L. Zhao, I. Weng Lao, L. Yu, J. Wang
• Journal: Annals of Diagnostic Pathology
• Published: 2019;38:43-50
• Cited by: 41 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We present our experience with 75 cases of well-differentiated papillary mesothelioma (WDPM) that were diagnosed at our institution between 2000 and 2017. The patients included 58 females and 17 males with age ranging from 18 to 69 years (mean, 42 years). Clinically, the vast majority of WDPMs were incidental findings during laparotomy or laparoscopic surgery for a variety of benign or malignant disease. The lesion manifested as either a small solitary nodule or multiple miliary nodules on the peritoneum or serosal surfaces of internal organs. Histologically, 67 cases were consistent with a classical WDPM, of which 6 cases contained microinvasive foci and 1 case had malignant transformation. Eight cases were hybrid tumors with variable combined component of adenomatoid tumor (n = 4), multicystic mesothelioma (n = 2), and both (n = 2). By immunohistochemistry, besides calretinin, D2-40, CK5/6 and WT1, 94% (29/31) of cases also showed immunostaining for PAX8. In comparison, PAX8 staining was only present in 12% (6/50) of epithelioid malignant mesothelioma selected as control cases. Follow-up information available in 46 cases revealed no signs of tumor progression or local recurrence except for the case that showed transformation to a fully malignant mesothelioma after a period of 15 years. Our comprehensive study further expanded the clinical and histopathological spectrum of WDPM. Compared with epithelioid malignant mesothelioma, PAX8 staining is highly sensitive and specific for WDPM (P < 0.001).

Copyright © 2018. Published by Elsevier Inc.

In plain English

This was a review of 75 consecutive cases of well-differentiated papillary mesothelioma (WDPM), a rare mesothelial tumor, diagnosed at Fudan University Shanghai Cancer Center, China, from 2000 to 2017. The patients were 58 women and 17 men; the 74 with known ages were 18 to 69. Most tumors were in the abdominal or pelvic peritoneum, and 3 were in the pleura. In 57 of 63 cases with clinical records (90%), the tumor was found incidentally during surgery for other conditions. Of the two pleural WDPM patients who had symptoms, one had a history of asbestos exposure. Six of 67 classical cases had microinvasive foci. Eight cases were combined with adenomatoid tumor, multicystic mesothelioma, or both. The marker PAX8 stained 29 of 31 WDPM cases (94%) but only 6 of 50 epithelioid malignant mesotheliomas (12%). Of 46 patients followed, 39 were alive without recurrence or progression; six died of associated carcinomas. One tumor became an epithelioid malignant mesothelioma 15 years later. The authors concluded PAX8 helps separate WDPM from epithelioid malignant mesothelioma in most instances but should be interpreted with caution.

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 single-institution case series (review of pathology files), with immunohistochemistry and a comparison group of epithelioid malignant mesothelioma cases for PAX8 staining
• Who was studied: 75 patients with WDPM (58 females, 17 males). Ages were available for 74 patients and ranged from 18 to 69 years (mean 42); one patient's age was not available. Cases were diagnosed in Shanghai, China, 2000 to 2017. Controls for PAX8 were 50 epithelioid malignant mesotheliomas (14 pleural, 32 peritoneal, 4 tunica vaginalis testis).
• Exposure: Not an exposure study. Asbestos is mentioned for this series only once. The series had 3 pleural WDPM cases, and 2 of these patients had symptoms (dyspnoea, cough, pleural effusions). One of those 2 symptomatic pleural patients had a history of asbestos exposure.
• Main results:
  • In 57 of 63 cases with recorded clinical data (90%), the WDPM was an incidental finding during surgery for other benign or malignant disease.
  • Most tumors were in the abdominal or pelvic peritoneum or on the serosal surfaces of abdominal and pelvic organs. Three were in the pleura and 2 in the testicular tunica vaginalis.
  • Of 67 classical WDPM cases, 6 had invasive foci limited to the submesothelial layers.
  • Eight cases were hybrid tumors: 4 with adenomatoid tumor, 2 with multicystic mesothelioma, and 2 with both.
  • PAX8 staining was seen in 94% (29/31) of WDPM cases. GLUT-1 staining was seen in 89% (16/18) of WDPM cases.
  • Among the 50 epithelioid malignant mesothelioma control cases, 6 (12%) showed PAX8 staining.
  • Compared with epithelioid malignant mesothelioma, PAX8 staining had a sensitivity of 94% and a specificity of 88% for WDPM (P less than 0.001).
  • Of 46 patients with follow-up (5 to 136 months), 39 were alive with no evidence of recurrence or tumor progression.
  • One WDPM developed into an epithelioid malignant mesothelioma after a 15-year interval.
  • Six patients died of associated carcinomas: 3 pancreatic, plus 1 each of gastric, ovarian and cervical carcinoma.
  • None of 10 WDPM cases tested by FISH showed p16 deletion.
• The authors' conclusion: The authors concluded that PAX8 is a useful marker for separating WDPM from epithelioid malignant mesothelioma in most instances. They cautioned that it should be interpreted with care, because a small set of epithelioid malignant mesotheliomas also express it.
• Limitations the authors state:
  • Only 2 cases were stained for IMP3, so its diagnostic value in WDPM remains to be evaluated.

Topics

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

Medical terms in this study, explained in our Lexicon: Well-Differentiated Papillary Mesothelioma, Laparotomy, Peritoneum, Serosal Surface, Malignant Transformation, Adenomatoid Tumor, Multicystic Mesothelioma (MCM), Immunohistochemistry.

Related studies

• Aberrant Pax-8 expression in well-differentiated papillary mesothelioma and malignant mesothelioma of the peritoneum: a clinicopathologic study — D. Xing, N. Banet, et al. (2018)
• Clinicopathological Characteristics of Well-differentiated Papillary Mesothelioma of The Peritoneum: A Single-institutional Experience of 12 Cases — M. Kim, H.S. Kim (2019)
• Well-differentiated papillary mesothelioma: a clinicopathological and immunohistochemical study of 18 cases with additional observation — X. Chen, W. Sheng, et al. (2013)
• Well-differentiated papillary mesothelioma of the pleura: a series of 24 cases — F. Galateau-Sallé, J.M. Vignaud, et al. (2004)
• Collagenous Spherulosis in Well-Differentiated Papillary Mesothelioma in a Female With Multilocular Peritoneal Inclusion Cysts — B. AbdullGaffar, L.G. Raman (2019)
• Malignant transformation of well-differentiated papillary mesothelioma 13 years after the diagnosis: a case report — L. Costanzo, S. Scarlata, et al. (2014)

Browse more research in Annals of Diagnostic Pathology, or return to medical research.