Primary Malignant Mesothelioma of the Peritoneum Mistaken for Peritoneal Tuberculosis due to Elevated Cancer Antigen 125

Our plain-English summary of Primary Malignant Mesothelioma of the Peritoneum Mistaken for Peritoneal Tuberculosis due to Elevated Cancer Antigen 125, by J.H. Oh, M.J. Oh (The Korean Journal of Gastroenterology = Taehan Sohwagi Hakhoe Chi, 2019).

The study

• Authors: J.H. Oh, M.J. Oh
• Journal: The Korean Journal of Gastroenterology = Taehan Sohwagi Hakhoe Chi
• Published: 2019;74(4):232-238
• Type of article: Case report
• Read it: PubMed · Publisher · Free full text

Abstract

Adifferential diagnosis of ascites is always challenging for physicians. Peritoneal tuberculosis is particularly difficult to distinguish from peritoneal carcinomatosis because of the similarities in clinical manifestations and laboratory results. Although the definitive diagnostic method for ascites is to take a biopsy of the involved tissues through laparoscopy or laparotomy, there are many limitations in performing biopsies in clinical practice. For this reason, physicians have attempted to find surrogate markers that can substitute for a biopsy as a confirmative diagnostic method for ascites. CA 125, which is known as a tumor marker for gynecological malignancies, has been reported to be a biochemical indicator for peritoneal tuberculosis. On the other hand, the sensitivity of serum CA 125 is low, and CA 125 may be elevated due to other benign or malignant conditions. This paper reports the case of a 66-year-old male who had a moderate amount of ascites and complained of dyspepsia and a febrile sensation. His abdominal CT scans revealed a conglomerated mass, diffuse omental infiltration, and peritoneal wall thickening. Initially, peritoneal tuberculosis was suspected due to the clinical symptoms, CT findings, and high serum CA 125 levels, but non-specific malignant cells were detected on cytology of the ascitic fluid. Finally, he was diagnosed with primary malignant peritoneal mesothelioma after undergoing a laparoscopic biopsy.

In plain English

This was a case report from CHA Gumi Medical Center in Korea about a 66-year-old man referred with abdominal swelling and discomfort lasting 2 or 3 weeks. He was a farmer who had sometimes worked at construction sites in his younger years. The authors described the case as malignant peritoneal mesothelioma without asbestos exposure. Doctors first suspected tuberculosis of the peritoneum (the lining of the abdomen). His blood level of the marker CA 125 was raised, at 100.8 μg/mL against a reference range of 0-35 μg/mL. Tests on fluid from his abdomen also pointed that way, and CT showed a 4.4×5.5 cm mass. However, a stain of the fluid for acid-fast bacteria, used to look for tuberculosis, was negative, and suspicious malignant cells were found. A laparoscopic biopsy confirmed malignant mesothelioma of the peritoneum, epithelioid type. The patient died of severe sepsis before starting chemotherapy. The authors concluded that giving tuberculosis treatment without a confirmed diagnosis would have delayed the correct diagnosis. They also concluded that a high CA 125 level should not settle the diagnosis in patients with fluid in the abdomen of unknown cause.

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 66-year-old man with no specific medical history, referred from a local clinic to CHA Gumi Medical Center, Gumi, Korea, because of abdominal distension
• Exposure: No fiber type or asbestos product is named. The patient was a farmer who had sometimes worked at construction sites when younger. The authors describe the case as being without asbestos exposure. He also had a 30 pack-year smoking history.
• Main results:
  • The patient's serum (blood) CA 125 level was elevated at 100.8 μg/mL, against a reference range of 0-35 μg/mL.
  • In the patient's abdominal (ascitic) fluid, the adenosine deaminase level was 69.1 U/L (reference less than 39 U/L) and the peritoneal CA 125 level was 651.5 μg/mL.
  • CT of the patient's abdomen showed a 4.4×5.5 cm conglomerated mass among the portal vein, pancreas neck and liver, along with omental infiltration, ascites and peritoneal thickening.
  • Acid-fast bacteria (AFB) staining of the patient's ascitic fluid was negative, and suspicious malignant cells were found on cytology.
  • At laparoscopy, multiple whitish patch nodules were seen throughout the patient's peritoneum, omentum and bowel walls.
  • Histology and immunohistochemical staining of the biopsies showed malignant mesothelioma of the peritoneum, epithelioid type.
  • Interferon-gamma release assays and the tuberculin skin test were not performed on this patient.
  • The patient was referred for chemotherapy but died of severe sepsis with increased pleural effusion before starting it.
• The authors' conclusion: The authors concluded that empirical anti-tuberculosis treatment would have delayed a definitive diagnosis and proper treatment. They also concluded that all possibilities should be considered in patients with ascites of unknown cause until a definite diagnosis is made, regardless of high CA 125 levels.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Peritoneum, Ascites, Biopsy, Laparotomy, Tumor Marker, CT Scan, Cytology.

Related studies

• CA125 suppresses amatuximab immune-effector function and elevated serum levels are associated with reduced clinical response in first line mesothelioma patients — N.C. Nicolaides, C. Schweizer, et al. (2018)
• CT findings and serum ca 125 levels in malignant peritoneal mesothelioma: report of 11 new cases and review of the literature — M. Kebapci, E. Vardareli, et al. (2003)
• Peritoneal malignant mesothelioma (PMM), and primary peritoneal serous carcinoma (PPSC) and reactive mesothelial hyperplasia (RMH) of the peritoneum. Immunohistochemical and fluorescence in situ hybridisation (FISH) analyses — T. Kawai, S. Tominaga, et al. (2016)
• Tissue Xpert™ MTB/Rif assay is of limited use in diagnosing peritoneal tuberculosis in patients with exudative ascites — C. Bera, J.S. Michael, et al. (2015)
• Value of mesothelial and epithelial antibodies in distinguishing diffuse peritoneal mesothelioma in females from serous papillary carcinoma of the ovary and peritoneum — R.L. Attanoos, R. Webb, et al. (2002)
• Malignant Peritoneal Mesothelioma with Latent Tuberculosis Infection — N. Inoue, K. Takumi, et al. (2021)

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