Well-differentiated papillary mesothelioma, possibly giving rise to diffuse malignant mesothelioma: a case report

Our plain-English summary of Well-differentiated papillary mesothelioma, possibly giving rise to diffuse malignant mesothelioma: a case report, by K. Washimi, T. Yokose, Y. Amitani, et al (Pathology International, 2013).

The study

• Authors: K. Washimi, T. Yokose, Y. Amitani, M. Nakamura, S. Osanai, H. Noda, K. Kawachi, H. Takasaki, M. Akaike, Y. Kameda
• Journal: Pathology International
• Published: 2013;63(4):220-5
• Type of article: Case report
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Well-differentiated papillary mesothelioma (WDPM) is a distinct subtype of mesothelial tumor from diffuse malignant mesothelioma (DMM), with an uncertain malignant potential. The relationship between WDPM and DMM, with regard to the ability of the former to develop into the latter, is also unknown. A 58-year-old woman, diagnosed with a rectal carcinoid tumor, underwent removal of the lymph nodes via the abdomen in 2004. A large number of white miliary nodules were identified on the mesentery and peritoneum, which were histologically diagnosed as WDPM. No further therapy was administered, but the patient was followed-up using imaging methods. Seven years later, an abdominal wall mass was discovered using positron emission tomography-computed tomography, and a laparotomy biopsy was performed. DMM was diagnosed, because mesothelioma with extended invasion had been histologically identified. Mesothelioma similar to papillary proliferation was present on the outer layer of the peritoneum, and an infiltrating lesion with continuous restiform or solid-like structures was noted. WDPM was believed to have undergone malignant transformation. Compared to DMM, WDPM has a good prognosis and is considered a benign or borderline neoplasm. Our findings suggest that WDPM does have malignant potential, however, because histological findings indicated a malignant transformation of WDPM to DMM.

© 2013 The Authors. Pathology International © 2013 Japanese Society of Pathology and Wiley Publishing Asia Pty Ltd.

In plain English

This case report described a 58-year-old woman in Japan with no history of asbestos exposure. In 2004, during surgery for a rectal carcinoid tumor, surgeons found many white nodules up to 5 mm in size on the lining of her abdomen (the peritoneum and mesentery). These were diagnosed as well-differentiated papillary mesothelioma (WDPM), and they showed no invasion. She received no further treatment and was monitored with CT scans every 4 months and yearly MRI. Seven years later, a thickened area of the abdominal wall was biopsied. It showed a surface lesion resembling the 2004 tumor next to a lesion invading the abdominal muscle, and it was diagnosed as diffuse malignant mesothelioma. In the invasive part, cell nuclei were more than twice as large on average. The growth marker Ki-67 and the protein p53 were also positive more often there (12.2% and 12.7%) than in the surface lesion (5.6% and 6.8%). A genetic test for p16 deletion could not be interpreted. The authors concluded that malignant transformation of WDPM was highly probable, while noting that the two tumors might be unrelated.

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: case report
• Who was studied: One 58-year-old woman with no history of asbestos exposure, reported by authors at Kanagawa Cancer Center, Yokohama, Japan, and followed from 2004 to 2011
• Exposure: No asbestos exposure was reported. The article studied the course of a peritoneal mesothelial tumor, not an exposure.
• Main results:
  • In 2004, many white miliary nodules up to 5 mm on the mesentery and peritoneum were diagnosed as WDPM. None of the nodules showed invasion.
  • After surgery the patient was monitored without therapy, with contrast-enhanced CT every 4 months and MRI annually, for 7 years.
  • In 2011, the thickened abdominal wall showed a papillary surface lesion similar to the 2004 WDPM, next to an invasive lesion that invaded the abdominal muscular wall. Diffuse malignant mesothelioma was diagnosed.
  • The average cross-sectional nuclear area in the 2011 invasive lesion (mean 48.92) was more than twice that of the 2011 surface lesion (23.2) and the 2004 lesion (23.19), based on 100 cell nuclei each.
  • p53 positivity was 1.2% (6/500) in 2004, 6.8% (68/1000) in the 2011 surface lesion and 12.7% (127/1000) in the 2011 invasive lesion. Ki-67 positivity was 1.2% (12/1000), 5.6% (56/1000) and 12.2% (122/1000) in the same three samples.
  • GLUT-1 was negative in the 2004 lesion but positive in about 20% of each 2011 lesion area. The other immunostaining results were almost identical between 2004 and 2011.
  • Ascitic fluid cytology in 2011 was very similar to 2004, except that overlapping and size differences of nuclei were slightly more frequent.
• The authors' conclusion: The authors concluded that there was a high probability that WDPM had undergone malignant transformation to diffuse malignant mesothelioma in this patient, suggesting that WDPM has the potential to become malignant. They added that cytology of ascitic fluid and imaging may be useful in detecting this change.
• Limitations the authors state:
  • The authors acknowledged that the WDPM may be different from, and unrelated to, the 2011 diffuse malignant mesothelioma.
  • The p16 deletion test (FISH) could not be interpreted because the control probe gave no signal.
  • The negative GLUT-1 result in 2004 may have occurred because the papillary lesion was too small.

Topics

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

Medical terms in this study, explained in our Lexicon: Well-Differentiated Papillary Mesothelioma, Malignant Mesothelioma, Mesentery, Peritoneum, Laparotomy, Biopsy, Mesothelioma, Malignant Transformation.

Related studies

• Simultaneous occurrence of a rectal carcinoma and a diffuse well differentiated papillary mesothelioma of the peritoneum — G.R. Jatzko, J. Jester (1997)
• Therapeutic strategies for well-differentiated papillary mesothelioma of the peritoneum — Y.K. Lee, H.J. Jun, et al. (2013)
• Well-differentiated papillary mesothelioma with invasive foci — A. Churg, T. Allen, et al. (2014)
• Well-differentiated papillary mesothelioma — K.J. Butnor, T.A. Sporn, et al. (2001)
• Well-differentiated papillary mesothelioma of the female peritoneum: a clinicopathologic study of 26 cases — A. Malpica, S. Sant'Ambrogio, et al. (2012)
• Combined adenomatoid tumor and well differentiated papillary mesothelioma of the omentum — Y. Hatano, Y. Hirose, et al. (2011)

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