Well-differentiated papillary mesothelioma with invasive foci

Our plain-English summary of Well-differentiated papillary mesothelioma with invasive foci, by A. Churg, T. Allen, A.C. Borczuk, et al (The American Journal of Surgical Pathology, 2014).

The study

• Authors: A. Churg, T. Allen, A.C. Borczuk, P.T. Cagle, F. Galateau-Sallé, H. Hwang, B. Murer, V.V. Murty, N. Ordonez, H.D. Tazelaar, M. Wick
• Journal: The American Journal of Surgical Pathology
• Published: 2014;38(7):990-8
• Cited by: 64 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Well-differentiated papillary mesotheliomas (WDPMs) are usually encountered as incidental findings in the peritoneal cavity in women. Most WDPMs are benign, and the histologic features that indicate a more aggressive course are controversial. We report 20 cases of WDPM, which contained invasive foci. Thirteen cases arose in the peritoneal cavity, 1 in a hernia sac, 3 in the pleural cavity, and 3 in hydroceles. The female:male ratio was 16:4, and age range was 7 to 74 years. Tumor was multifocal in 15 cases. Some tumors showed back-to-back papillae, a pattern mimicking invasion but discernible on pan-keratin stain as compressive crowding. True invasive patterns ranged from simple bland-appearing glands invading the stalks of the papillae to solid foci of invasive tumor of higher cytologic grade than the original WDPM. All 5 tested cases were negative for p16 deletion by fluorescence in situ hybridization, but 2/3 had abnormal karyotypes. Recurrences were seen in 8 patients, and in 4 multiple recurrences were documented. Of 16 patients with follow-up, 14 are alive from periods of 6 months to 6 years (average 3.5 y), and 2 have known recurrent disease. One patient died of disseminated tumor at 8 years but without histologic confirmation of the nature of the tumor. We conclude that WDPM with invasive foci in the papillae appear to be prone to multifocality and recurrence, but that they rarely give rise to life-threatening disease. We suggest that these lesions be called WDPM with invasive foci to alert clinicians to the possibility of recurrence.

In plain English

This article was a case series of well-differentiated papillary mesothelioma (WDPM), a tumor of the lining cells of body cavities, in which small areas of invasion were found. The authors took 31 possible cases from their consultation files and, after joint review, accepted 20. There were 16 women and 4 men, aged 7 to 74. Thirteen tumors arose in the peritoneal cavity, 1 in a hernia sac, 3 in the pleural cavity and 3 in hydrocele sacs. Lesions were multifocal in 15 cases. Invasive areas were always a small part of the lesion, and in 1 case they invaded fat. None of the 5 cases tested showed p16 deletion. Two of the 3 cases whose chromosomes were analyzed had abnormal results. Follow-up data were available for 16 patients. Eight patients had recurrences, 4 of them more than once. Fourteen were alive at last follow-up. One patient died of disseminated disease after 8 years, but tissue never confirmed what that disease was. The authors concluded that these lesions tend toward multifocality and recurrence. The article did not discuss asbestos.

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 series (clinicopathologic review of cases from the authors' consultation files)
• Who was studied: 20 patients with WDPM containing invasive foci (16 women, 4 men, aged 7 to 74): 13 peritoneal, 1 hernia sac, 3 pleural, 3 hydrocele sacs
• Main results:
  • Lesions were multifocal in 15 of the 20 cases
  • In some tumors, crowded back-to-back papillae looked like invasion at first, but keratin stains showed that the original papillae were still present (compressive crowding, not invasion)
  • Invasive foci always made up a small area of the lesion; in 1 case (case 13) they invaded fat
  • None of the 5 cases tested by p16 FISH showed p16 deletion
  • Of the 3 cases successfully karyotyped, 2 showed clonal chromosome abnormalities and 1 was normal
  • Follow-up data were available for 16 patients. Recurrence was seen in 8 patients, 4 of whom had multiple recurrences
  • 14 patients were alive at last follow-up (range 6 months to 6 years, mean 3.5 years)
  • One patient (case 17) died of disseminated disease after 8 years, without histologic confirmation of what the disease was
  • Where material from recurrences was available for review, the recurrences looked like WDPM, not malignant mesothelioma
• The authors' conclusion: The authors concluded that WDPMs with invasive foci within the papillae tend toward multifocality and recurrence, sometimes repeated in the same patient. They suggested calling these lesions 'WDPM with invasive foci'.
• Limitations the authors state:
  • The authors were cautious about using p16 FISH for diagnosis, because few cases were tested and only some diffuse malignant mesotheliomas show p16 deletion
  • Pathology samples from the patient who died of disseminated disease could not be retrieved, so the nature of that tumor is unknown
  • The case with invasion into fat was lost to follow-up

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, Peritoneal Cavity, Pleural Cavity, Hydrocele, Papillae, Fluorescence In Situ Hybridization (FISH).

Related studies

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• BAP1 loss is unusual in well-differentiated papillary mesothelioma and may predict development of malignant mesothelioma — H.E. Lee, J.R. Molina, et al. (2018)
• Therapeutic strategies for well-differentiated papillary mesothelioma of the peritoneum — Y.K. Lee, H.J. Jun, et al. (2013)
• Combined adenomatoid tumor and well differentiated papillary mesothelioma of the omentum — Y. Hatano, Y. Hirose, et al. (2011)
• Well-differentiated papillary mesothelioma of the epididymis in a man with recurrent haematospermia — L.R. Bonetti, L. Schirosi, et al. (2012)
• Well-differentiated papillary mesothelioma of the female peritoneum: a clinicopathologic study of 26 cases — A. Malpica, S. Sant'Ambrogio, et al. (2012)

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