Rare confounder: benign multicystic peritoneal mesothelioma in a patient with mucinous colon adenocarcinoma

Our plain-English summary of Rare confounder: benign multicystic peritoneal mesothelioma in a patient with mucinous colon adenocarcinoma, by K.K. Patel, G.P. Stinson, K.P. Terracina, et al (Journal of Surgical Case Reports, 2024).

The study

• Authors: K.K. Patel, G.P. Stinson, K.P. Terracina, J.F. Nordenstam, T.E. Read
• Journal: Journal of Surgical Case Reports
• Published: 2024;2024(9):rjae569
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Benign multicystic peritoneal mesothelioma (BMPM) is a rare condition, in which patients have multiple cystic lesions of the peritoneum. BMPM can mimic mucinous carcinomatosis and can thus create a diagnostic dilemma. We present the case of a 76-year-old woman who was referred for management of ascending colon adenocarcinoma and was noted to have several nonspecific cystic lesions in the abdomen and pelvis on preoperative computed tomography and diagnostic laparoscopy. Frozen section analysis suggested the lesions contained 'mucin'. Due to concern for metastases, right colectomy was aborted. Final histologic analysis of the laparoscopic biopsies revealed mesothelial cysts, consistent with BMPM, unrelated to her colon adenocarcinoma. Laparoscopic right colectomy was performed 2 weeks later. BMPM can create diagnostic and therapeutic uncertainty in patients with known visceral malignancies when discovered incidentally. Frozen section analysis may not be accurate in differentiating the two, and final histologic confirmation should be sought prior to definitive treatment.

Published by Oxford University Press and JSCR Publishing Ltd. © The Author(s) 2024.

In plain English

This was a case report of one patient. A 76-year-old woman was referred for surgery for adenocarcinoma of the ascending colon. A preoperative CT scan showed the colon mass and multiple nonspecific cystic lesions in the abdomen and pelvis. At diagnostic laparoscopy the cysts looked like mucinous carcinomatosis (spread of mucus-producing cancer), and a rapid frozen-section test of biopsied cysts showed mucin but no metastatic adenocarcinoma. Because of concern about cancer spread, colon removal was deferred. Final microscopic analysis instead found mesothelial cysts consistent with benign multicystic peritoneal mesothelioma (BMPM), unrelated to her colon cancer. She had a laparoscopic-assisted right colectomy 2 weeks later, and the tumor was a Stage I (pT2N0) mucinous adenocarcinoma. The authors chose to monitor the BMPM rather than remove it. They concluded that frozen section may not be adequate to make the diagnosis and that surgical excisional biopsy and histologic analysis may be required. The article did not examine asbestos. Its introduction states, citing earlier literature, that BMPM is unrelated to asbestos exposure.

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 (single patient)
• Who was studied: One 76-year-old woman referred for management of ascending colon adenocarcinoma. The authors are from the Division of Gastrointestinal Surgery, University of Florida. Dates of treatment are not given.
• Exposure: No asbestos exposure was studied, and none was reported for this patient. The introduction states, citing earlier literature (reference 3), that benign multicystic mesothelioma is unrelated to asbestos exposure, in contrast to what the authors call pulmonary mesothelioma.
• Main results:
  • Preoperative CT in this patient showed a mass in the ascending colon and multiple nonspecific cystic lesions in the peritoneal cavity of the abdomen and pelvis.
  • The patient's carcinoembryonic antigen (a blood tumor marker) measured 0.8 ng/mL.
  • At diagnostic laparoscopy, the cysts looked like mucinous carcinomatosis.
  • Frozen section analysis of the biopsied cysts showed mucin but no evidence of metastatic adenocarcinoma. Colectomy was deferred because of concern for carcinomatosis.
  • Final histologic analysis found mesothelial cysts consistent with BMPM, unrelated to the patient's colon adenocarcinoma.
  • The patient had a laparoscopic-assisted right colectomy 2 weeks after the diagnostic laparoscopy.
  • The colon tumor was a pT2N0 (Stage I) mucinous adenocarcinoma with negative margins.
  • The authors chose to follow the patient's BMPM with observation rather than excision.
• The authors' conclusion: The authors concluded that frozen section analysis may not be adequate to diagnose BMPM and that surgical excisional biopsy and histologic analysis may be required for a definitive diagnosis.

Topics

Medical terms in this study, explained in our Lexicon: Peritoneal Mesothelioma, Adenocarcinoma, Peritoneum, Diagnostic Laparoscopy, Frozen Section.

Related studies

• Thinking outside the pelvis: benign peritoneal multicystic mesothelioma of the ascending colon — B. Murphy, M. Ismaeil, et al. (2023)
• Successful Complete Laparoscopic Resection of Benign Peritoneal Multicystic Mesothelioma Adherent to the Ascending Colon: A Case Report — Y. Kitamura, M. Miguchi, et al. (2025)
• Benign Multicystic Peritoneal Mesothelioma: A Rare Condition in an Uncommon Gender — M.S. Khurram, H. Shaikh, et al. (2017)
• Benign Multicystic Peritoneal Mesothelioma (BMPM) as a rare cause of abdominal pain in a young male: case report and review of the literature — S. Gussago, P. Spina, et al. (2019)
• Benign multicystic peritoneal mesothelioma: a rare tumour of the abdomen — S. Somasundaram, M. Khajanchi, et al. (2015)
• Benign multicystic peritoneal mesothelioma (BMPM) presenting with ambiguous symptoms: A rare case report — A. Hamza, A. Zazo, et al. (2021)

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