Peritoneal mesothelioma is a rare and aggressive malignancy [ of the peritoneum ] that often presents with non-specific abdominal symptoms such as ascites, leading to delayed diagnosis and treatment. It poses significant diagnostic challenges, especially in the absence of classical risk factors like asbestos exposure.
We report the case of a 60-year-old woman with a background of coeliac disease and no known asbestos exposure, who presented with progressive abdominal distension and ascites. Initial investigations, including imaging, paracentesis, cytology and liver biopsy, failed to reveal a definitive cause. Despite multiple evaluations and treating a presumptive diagnosis of sarcoidosis, her symptoms persisted. One year after the initial presentation, imaging revealed peritoneal nodularity and enhancement. Following biopsy and immunohistochemistry, a multidisciplinary team discussion led to the diagnosis of peritoneal mesothelioma. The patient was commenced on chemotherapy which showed clinical improvement.
This case underscores the importance of maintaining a high index of suspicion for rare malignancies such as peritoneal mesothelioma in patients with recurrent unexplained ascites, even in the absence of classical risk factors. Early multidisciplinary involvement and persistence in diagnostic evaluation are essential for timely diagnosis and management, which may improve patient outcomes in complex presentations.
Introduction
Mesothelial cells are specialised cells lining the body’s cavities and internal organs. The peritoneum, which is a membrane lining the abdominal cavity, is one of the many membranes on the body on which these cells can be found. The mesothelial cells present on the peritoneum are prone to a rare and aggressive cancer known as peritoneal mesothelioma.
It is estimated that the incidence of this type of mesothelial cancer (also known as a ‘mesothelioma’) is approximately two per 1,000,000 people annually [1]. Although peritoneal mesothelioma accounts for only 15% of all mesothelioma cases, it poses significant challenges in both diagnosis and treatment [2]. Among the several more commonly observed types of mesotheliomas is pleural mesothelioma, for which asbestos exposure is a well-established risk factor, but its link to peritoneal mesothelioma is less clear; fewer than 50% of patients report prior asbestos exposure [3], and some cases are considered idiopathic.
Peritoneal mesothelioma can present as a localized abdominal disease; however, most cases exhibit diffuse involvement of the peritoneum. It may also extend into the pleural cavity, leading to pleural effusion. Metastasis (spreading of the cancer) to abdominal and pelvic lymph nodes is rare, and extra-abdominal metastases are exceedingly uncommon [4]. There are no specific or reliable tumour markers for the diagnosis of peritoneal mesothelioma. Although CA-125 (a tumour marker) is often elevated, it lacks specificity as it can be elevated in many other conditions like ovarian cancer and is primarily useful for monitoring disease recurrence or progression rather than for initial diagnosis [5].
Case Presentation
A 60-year-old woman with a background of coeliac disease, hypertension, gastro-oesophageal reflux disease (GORD) and osteoporosis presented to the emergency department. She reported progressive abdominal distension over the past five months, associated with back pain, orthopnoea and lower limb swelling. She also reported difficulty climbing stairs. There were no symptoms suggestive of hepatic, renal or cardiac disease. Her family history was significant for bowel cancer in her father and brother. The patient was a retired carer from a nursing home with no prior history of asbestos exposure. She was a non-smoker and did not consume alcohol.
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