Communicating imaging findings in peritoneal mesothelioma: the impact of ‘PAUSE’ on surgical decision-making

Abstract

The peritoneal cavity is the second commonest site of mesothelioma after the pleural cavity. There are five histological types of peritoneal mesothelioma with variable symptomatology, clinical presentation and prognosis. Cystic mesothelioma is a borderline malignant neoplasm with a favourable prognosis, well-differentiated papillary mesothelioma is generally a low-grade malignancy, and all other varieties such as epithelioid, sarcomatoid and biphasic mesothelioma are highly malignant types of peritoneal mesothelioma with poor prognosis. Malignant peritoneal mesothelioma was considered inevitably fatal prior to the introduction of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in selected cases where long-term survival and cure could be achieved. However, the survival benefits following CRS and HIPEC mainly depend on completeness of cytoreduction, which come at the cost of high morbidity and potential mortality. Using the acronym ‘PAUSE’, we aimed at describing the key imaging findings that impact surgical decision-making in patients with peritoneal mesothelioma. PAUSE stands for peritoneal cancer index, ascites and abdominal wall disease, unfavourable sites of involvement, small bowel and mesenteric disease and extraperitoneal disease. Reporting components of ‘PAUSE’ is crucial for patient selection. Despite limitations of CT in accurately depicting the volume of disease, describing findings in terms of PAUSE plays an important role in excluding patients who might not benefit from CRS and HIPEC.

Benign multicystic peritoneal mesothelioma mimicking mucinous ovarian neoplasm with pseudomyxoma peritonei

“…Peritoneal mesothelioma is a rare neoplasm arising from the mesothelial cells lining the peritoneal cavity and is the second most common mesothelioma after the pleural mesothelioma 1. There are five main histological types of peritoneal mesothelioma and they have different clinical behaviour.…”

“…There are five main histological types of peritoneal mesothelioma and they have different clinical behaviour. Cystic mesothelioma is a borderline malignant neoplasm; well-differentiated papillary mesothelioma is a low-grade malignant subtype; and the other types such as epithelioid, sarcomatoid and biphasic subtypes of peritoneal mesothelioma are highly malignant 1. Cystic mesothelioma is a rare neoplasm, accounting for only 3%–5% of peritoneal mesothelioma and has many synonyms such as peritoneal inclusion cyst, multicystic peritoneal mesothelioma and benign multicystic peritoneal mesothelioma (BMPM) 1 2.…”

“…BMPM is usually considered to be benign as no cellular or nuclear atypia is seen histologically 4. However, it is increasingly accepted as a ‘borderline malignancy’ because the local recurrence rate is high 1. Peritoneal mesothelioma is more common in men, while BMPM is more common in young and middle-aged women 1.…”

“…However, it is increasingly accepted as a ‘borderline malignancy’ because the local recurrence rate is high 1. Peritoneal mesothelioma is more common in men, while BMPM is more common in young and middle-aged women 1. BMPMs are generally asymptomatic and it is found incidentally during routine diagnostic imaging tests or surgical procedures in the abdomen 5.…”

“…Besides, they can cause non-specific abdominal pain and discomfort, bloating, constipation, deep pelvic pain, dyspareunia, incontinence and anorexia if their sizes increase 2. Considering that BMPM is often found in the pelvis, it is difficult to differentiate from other pelvic and abdominal lesions, such as cystic lymphangioma, cystic adenomatoid tumours, malignant peritoneal mesothelioma, mesenteric and omental cysts, cystic endosalpingiosis and cystic ovarian masses, especially mucinous cystadenoma–adenocarcinoma, pseudomyxoma peritonei, endometriosis or peritoneal hydatidosis 1 2 5–9. Although there is no evidence-based guideline for treatment, it is usually considered that surgical resection with hyperthermic intraperitoneal chemotherapy (HIPEC) is the best option 6.…”