Multicystic peritoneal mesothelioma: a systematic review of the literature

Multicystic peritoneal mesothelioma in the myometrium during pregnancy: A case report and literature review

Multicystic peritoneal mesothelioma (MCPM) is a rare tumor originating from mesothelial cells, primarily affecting women of reproductive age and typically found in the pelvic peritoneum. Its occurrence in the myometrium is extremely rare. Currently, there have been no reported cases of MCPM in the myometrium during pregnancy, and existing clinical guidelines do not provide specific management recommendations for this condition. This article aimed to explore the diagnosis, management, and treatment for MCPM in the myometrium during pregnancy, thereby providing a valuable reference for clinicians dealing with similar cases.

Benign Cystic Mesothelioma of the Peritoneum Arising at the Greater Omentum in a 14-Year-Old Boy

INTRODUCTION

Mesothelioma arises from mesothelial cells. This tumor is very rare among pediatric abdominal neoplasms. We herein report an extremely rare case of acute abdomen with cystic mesothelioma of the peritoneum in a child.

CASE PRESENTATION

A 14-year-old boy was referred to our hospital for emergency surgery. Surgery revealed a primary tumor arising from the greater omentum. The tumor was macroscopically diagnosed as a benign omental lymphangioma and was resected en bloc with the greater omentum. A histopathological examination of the tumor revealed a simple columnar epithelium-like mesothelioma with poor cell-atypia. Immunohistochemical examination showed antibody reactivity in the cyst epithelium, including an anti-calretinin antibody. The final pathological diagnosis was a mesothelioma originating from the peritoneum.

CONCLUSIONS

In pediatric cases diagnosed with cystic lymphatic malformation, the possibility of peritoneal mesothelioma needs to be considered and carefully confirmed or ruled out.

Uncovering the True Diagnosis: A Case Report of Multilocular Peritoneal Inclusion Cyst

Peritoneal inclusion cysts (PICs) are rare, benign cystic tumors predominantly found in premenopausal females. They often present diagnostic challenges due to their asymptomatic nature and non-specific imaging features, requiring biopsy and immunohistochemistry for a definitive diagnosis. This report presents a case of a large, multilocular PIC initially misdiagnosed as a lymphangioma. A 29-year-old asymptomatic nulliparous female presented for follow-up after an abdominal ultrasound, conducted during a complicated cystitis workup, incidentally revealed a notable fluid collection adjacent to the spleen. Computed tomography of the abdomen and pelvis showed a complex cystic lesion in the left upper quadrant, measuring 7.6 x 11.7 cm. The finding was interpreted as a lymphangioma. Over six months, the lesion doubled in size, prompting further evaluation and doxycycline sclerotherapy. Despite eight months of treatment, the patient began to experience persistent symptoms of abdominal pressure, sharp groin pain, and decreased appetite. Magnetic resonance imaging revealed that the lesion had grown to 7.0 x 17.1 x 34.6 cm. An incisional biopsy confirmed PICs through pathology and immunohistochemistry. Genetic testing for hereditary cancer was negative. The patient underwent extensive surgical resection involving multiple organs, ultimately achieving no gross residual disease. This case underscores the diagnostic challenges posed by PICs and the necessity of biopsy for accurate diagnosis, differentiating them from lymphangiomas. It emphasizes the importance of a multidisciplinary approach and individualized treatment plans when managing PICs. Continued research and long-term follow-up are essential for refining treatment strategies for this rare condition.

Excision of benign multicystic peritoneal mesothelioma and deep infiltrating endometriosis with bowel involvement - A case report

Benign multicystic peritoneal mesothelioma (BMPM) is a rare peritoneal tumour. Treatment involves complete surgical resection, although recurrence rates are high. Notably, there are 7 documented cases of BMPM coexisting with endometriosis on histology and in the case reported here it was associated with deep infiltrating endometriosis. Examination of the 26-year-old nulliparous woman with deep dyspareunia, dyschezia and occasional rectal bleeding revealed restricted uterine mobility and a rectovaginal nodule. Magnetic resonance imaging (MRI) showed multiple clear cystic structures in the pelvis of unknown aetiology. Following discussion by a multidisciplinary team, a diagnostic laparoscopy was performed. Intraoperatively, bilateral endometriomas were identified, along with multiple fluid-filled cystic structures in the pelvis and on the anterior abdominal wall. An adhesiolysis and drainage of endometriomas was performed and the cystic structures were sent for histology. Histopathology confirmed BMPM, positive for AE1/3 and calretinin. The patient was referred to a mesothelioma malignancy institute and advised to undergo definitive surgery by the local endometriosis team. A joint surgical procedure with a colorectal team involved laparoscopic excision of peritoneal cysts, cystectomy for bilateral endometriomas, and excision of deep infiltrating endometriosis with bowel shaving. Histopathology revealed benign mesothelial cysts with foci of endometriosis. The patient had an uncomplicated recovery and is planned for long-term follow-up with the mesothelioma malignancy institute due to the high recurrence rate (up to 50 %). This case report suggests a definitive role of this two-stage procedure in patients with this diagnostic complexity and emphasises the role of multidisciplinary management.

Giant benign mesenteric cysts (mesothelioma and lymphangioma): A report of two cases

INTRODUCTION AND IMPORTANCE

Mesenteric cysts are a rare group of intra-abdominal tumors located in the mesentery or omentum, most of this lesion are asymptomatically but occasionally presents with non-specific symptoms, which makes diagnosis difficult.

CASE PRESENTATION

We present two cases of giant mesenteric cyst in our Institution, the first case is a women of 23 years with previous gynecologic surgery with chronic abdominal pain and large abdominal mass CT showed a giant intraabdominal 30 × 25 × 15 cm, the patient went to laparotomy and a large mesenteric tumor found. The Histopathology reported a Benign cyst mesothelioma (BCM). The second case is a 47 year male with intermittent abdominal pain and abdominal CT shows a 20x21x15 cm tumor. Laparotomy was performed. Histopathology reported a large lymphangioma.

CLINICAL DISCUSSION

BCM tumors are rare intrabdominal lesions often diagnosed in premenopausal women. Its etiopathogenesis is still unclear, associated risk factors are endometriosis, pelvic inflammatory disease and previous pelvic surgery. Lymphangiomas are an infrequent cyst tumors. It results from a failure in the evolutionary development of the lymphatic system, often localized in the head and neck and its localization in the abdomen is even rare. The definitive diagnosis is made by histopathology.

CONCLUSION

Mesenteric cysts diagnosis if often challenge due to nonspecific symptoms and significant overlap in imaging appearance between the different entities, its diagnosis should be in mind when encounter a cystic abdominal tumor, surgical complete removal of this tumors is the optimal treatment to prevent recurrence and complications.

A case of benign multicystic peritoneal mesothelioma

Benign Multicystic Peritoneal Mesothelioma (BMPM) is an exceedingly rare benign abdominal neoplasm with fewer than 200 cases reported worldwide. Owing to its rarity, vague clinical picture, and elusive causes, diagnosis is often delayed or missed. Histopathological examination and immunohistochemical staining are crucial for definitive diagnosis. However, due to lack of substantial literature, the standard of care and future prognosis remain subjects of inquiry. We present a case report of one female patient diagnosed with BMPM and treated with surgical resection.

[Gender medicine in peritoneal diseases]

Diseases of the peritoneum are divided into benign and malignant, whereby malignant diseases are more frequent. The incidence of peritoneal metastases is difficult to determine as they are frequently not listed separately in cancer databases and registries. Peritoneal metastases can be caused by many primary tumors but are particularly frequent in gastric, ovarian and colorectal carcinomas. Systemic chemotherapy shows gender-specific differences in the tolerability, especially gastrointestinal side effects and hematological toxicity occur more often in women. Surgical treatment options in selected patients include cytoreductive surgery with or without hyperthermic intraperitoneal chemoperfusion (HIPEC). The treatment recommendations depend on the primary tumor entity and the stage of the disease. Hysterectomy and/or salpingo-oophorectomy is often necessary during cytoreductive surgery. As the incidence of cancerous diseases is increasing in younger patients, the aspect of fertility is becoming increasingly more important. The iatrogenically induced menopause is another aspect that needs to be addressed after these types of procedures. Women with gastric and colorectal cancer tend to have a slightly better survival rate, especially in localized tumors; however, in advanced tumor stages the survival rates are comparable. Even if gender-specific differences in incidence, treatment response and adverse events are conspicuous, there is so far no exact explanation for these differences. More studies are needed in order to treat both genders as adequately as possible, with low adverse events and to achieve the best possible outcome.

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

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.

Case report: ATM A1159T mutation in malignant peritoneal mesothelioma may be associated with tumor recurrence

Malignant peritoneal mesothelioma is an exceedingly rare malignant tumor. Herein, we present a case of malignant peritoneal mesothelioma in a 59-year-old Chinese female patient who was stable after treatment for multiple relapses. Imaging revealed massive ascites and an irregular thickening of the peritoneal mesangium. Laparoscopic biopsy revealed heterogeneous cell nests in the parietal peritoneal fibrous tissue, which were confirmed by immunohistochemical staining for Calretinin, WT-1, and D2-40. In terms of genetic screening, BAP1, CSF1R, and other key driver gene variants closely related to malignant peritoneal mesothelioma have been explored in tumor tissues. Notably, CARD11 driver mutation was first found in all malignant peritoneal mesothelioma patients, and ATM A1159T gene mutation found in recurrent focal tissue may be associated with recurrent tumor recurrence.

Benign multicystic peritoneal mesothelioma in a sexagenerian man: an uncommon case presentation

BACKGROUND

Multicystic mesothelial cyst is a rare, and usually benign, tumor which is rarely diagnosed preoperatively due to the poor specificity of its symptomatology.

METHODS

We report the case of a 63-year-old man with multiple comorbidities (e.g. cryptogenic cirrhosis, chronic heart failure) and a history of surgical resection of a giant abdominal cyst, who complained of recurrent intermittent abdominal pain and vomiting that appeared several weeks before. Abdominal computed tomodensitometry (CT) revealed multiple diffusely localized cysts in the abdominal cavity, ranging from 30 mm to 210 mm.

RESULTS

The patient underwent surgical resection of twelve intra-abdominal cysts, identified at final pathology as benign mesothelial cysts, which were probably a recurrence following the previous surgery for a single intra-abdominal cyst. Three months later, the patient recurred with development of two new intraperitoneal cysts, with an increasing volume on CT at last follow-up (18 months). Surveillance was recommended given the patient's comorbidities and the absence of symptoms.

CONCLUSIONS

Surgical resection is the treatment of choice for multicystic peritoneal mesothelioma, a rare disease that should be considered more as a borderline tumor than a benign tumor, given the high risk of recurrence and possible malignant transformation.

Intra-Operative Diagnosis of Benign Multicystic Peritoneal Mesothelioma: A Case Report of Rare Entity and Lessons Learned

Benign multicystic peritoneal mesothelioma (BMPM), also known as multicystic peritoneal mesothelioma (MCPM), is a rare cystic neoplasm arising from the mesothelium lining of the abdominal and pelvic peritoneum. This entity has been disproportionately described in women of reproductive age. Both the etiology and pathogenesis of the condition are not well understood. Preoperative diagnosis is challenging as differentials are varied and include endometriosis, lymphangioma, pseudomyxoma peritonei, cystic adenomatoid tumor, and malignant peritoneal mesothelioma. Management options include cytoreductive surgery (CRS) with or without heated intraperitoneal chemotherapy (HIPEC). In this case report, we highlight the complexity of preoperative diagnosis, presentation, workup, treatment, and management of BMPM. We report the case of a female patient presenting with abdominal pain and imagining consistent with cystic intra-abdominal lesions. After an inconclusive percutaneous biopsy and a multi-disciplinary tumor board discussion, the patient was offered CRS with HIPEC. Intra-operative frozen section indicated benign epithelial lined cysts. CRS and HIPEC were performed. After a second opinion, the lesions were confirmed by pathology and immunohistochemistry to be BMPM. In this report, we discuss the gold standard of care for patients with BMPM to improve the disease control rate. This pathway is proposed in our study, and, thus, we conclude that BMPM should be considered in the differential diagnosis of patients presenting with symptomatic multiple intraperitoneal cystic lesions.

Endometriosis MR mimickers: T1-hyperintense lesions

Endometriosis is a chronic and disabling gynecological disease that affects women of reproductive age. Magnetic resonance imaging (MRI) is considered the cornerstone radiological technique for both the diagnosis and management of endometriosis. While MRI offers higher sensitivity compared to ultrasonography, it is prone to false-positive results, leading to decreased specificity. False-positive findings can arise from various T1-hyperintense conditions on fat-suppressed T1-weighted images, resembling endometriotic cystic lesions in different anatomical compartments. These conditions include hemorrhage, hyperproteic content, MRI artifacts, feces, or melanin. Such false positives can have significant implications for patient care, ranging from incorrect diagnoses to unnecessary medical or surgical interventions and subsequent follow-up. To address these challenges, this educational review aims to provide radiologists with comprehensive knowledge about MRI criteria, potential pitfalls, and differential diagnoses, ultimately reducing false-positive results related to T1-hyperintense abnormalities.Critical relevance statementMRI has a 10% false-positive rate, leading to misdiagnosis. T1-hyperintense lesions, observed in the three phenotypes of pelvic endometriosis, can also be seen in various other causes, mainly caused by hemorrhages, high protein concentrations, and artifacts.Key points• MRI in endometriosis has a 10% false-positive rate, leading to potential misdiagnosis.• Pelvic endometriosis lesions can exhibit T1-hyperintensity across their three phenotypes.• A definitive diagnosis of a T1-hyperintense endometriotic lesion is crucial for patient management.• Hemorrhages, high protein concentrations, lipids, and artifacts are the main sources of T1-hyperintense mimickers.

Primary splenic multicystic peritoneal mesothelioma in a young healthy male

Multicystic peritoneal mesothelioma (BMPM) is a rare, usually benign tumor that arises from peritoneal mesothelial cells that most commonly occurs in women of reproductive age. Pathogenesis of these tumors is thought to come from chronic inflammation from prior surgery, endometriosis, trauma, or recurrent peritonitis. Here we report a case of primary splenic BMPM in a 20-year-old male with no past medical or surgical history and without any typical risk factors for this condition. He underwent an open splenectomy without complication. Pathology revealed an 18 × 4 × 11 cm3 spleen with a cyst occupying 75% of the splenic surface. Sections revealed a multilocular cyst with trabeculated walls and immunohistochemical staining positive for cytokeratin (AE1/AE3) consistent with BMPM. One year post operatively he remains asymptomatic; however, his interval computed tomography (CT) scan revealed several sub centimeter nodules that either represents small splenules or neoplastic implants. These will be followed with close interval imaging.

Cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) for peritoneal mesothelioma: Canadian practices and outcomes

INTRODUCTION

Peritoneal mesothelioma (PM) is a rare malignancy originating from the peritoneal lining. Cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) is the standard-of-care for patients with isolated PM. Due to a paucity of prospective data there are several different HIPEC protocols. The aims of this study are to describe the CRS and HIPEC protocols for PM and patient outcomes across Canada.

METHODS

A multicenter retrospective study was performed on patients diagnosed and treated for PM with CRS and HIPEC in four major peritoneal disease centers in Canada between 2000 and 2021. Data on patient characteristics, treatment patterns, postoperative morbidity, recurrence, and survival were collected.

RESULTS

A total of 72 patients were identified. Mean age was 52 years (17-75) and 37.5% were male. Epithelioid (70.1%) and multicystic (13%) mesothelioma were the most common subtypes. Twenty-one patients (30%) were treated with neoadjuvant chemotherapy. CRS and HIPEC was performed in 64 patients (91.4%). Of these, the mean PCI was 22 (2-39) and cisplatin+doxorubicin was the most common HIPEC regimen (n = 33, 51.6%). A semi-closed coliseum technique was used in 68.8% of HIPECs and the mean duration of surgery was 486 min (90-1052). Clavien-Dindo III or IV complications occurred in 12 patients (16.9%). With a median follow-up of 24 months (0.2-104.4), we found a 5-year overall survival of 61% and a 5-year recurrence-free survival of 35%.

CONCLUSION

CRS and HIPEC is a safe and effective treatment modality for well-selected patients with PM, with some achieving prolonged survival.

Extrapelvic Endometriosis Mimicking Peritoneal Surface Malignancy: Case Report and a Review of Literature

Extrapelvic endometriosis is a rare presentation of endometriosis with atypical clinical symptoms. It can mimic peritoneal surface malignancy, as well as some abdominal infectious diseases. A 29-year-old Moroccan woman presented with abdominal pain, progressive abdominal distention, and an intermittent inflammatory syndrome. Imaging revealed multiple, progressively growing abdominal cysts. She had elevated tumor markers CA125 and CA19.9. Despite thorough investigation, several differential diagnoses persisted for a long time. Definitive pathological diagnosis could only be established after debulking surgery. Literature review on malignant and benign conditions causing multicystic abdominal distention is provided. When definitive diagnosis is not established, but suspicion for peritoneal malignancy remains, a debulking procedure can be undertaken. Organ preservation can be pursued whenever benign disease is still considered. In case of malignancy, short-term (curative) debulking procedure with or without hyperthermic intraperitoneal chemotherapy (HIPEC) can be proposed.

Rare Variants of Malignant Peritoneal Mesothelioma: a Literature Review

Primary peritoneal mesothelioma (PM) is a rare and aggressive malignancy that arises from the peritoneum and classified into diffuse malignant peritoneum mesothelioma (DMPM) and borderline variants, viz. multicystic peritoneal mesothelioma (MCPM) and well-differentiated papillary peritoneal mesothelioma (WDPPM). The borderline variants are rarer than conventional DMPM, are less aggressive form accounting for 3-5% of all cases of peritoneal mesothelioma. In this narrative review article, we have discussed the pathogenesis, clinical presentation, natural history, and management of these rarer variants of PM, viz. MCPM and WDPPM. Histologically, MCPM typically consists of small cysts composed of mesothelial epithelium with benign bland cuboidal cells with clear fluids; cells lack cellular atypia and have increased number of mitoses. WDPPM has specific papillary component with myxoid plump cores and single layer of bland mesothelial cells. Both the variants commonly present as incidental finding or symptoms of chronic abdominal pain, chronic pelvic inflammatory disease, pelvic mass, and infertility. In the absence of treatment, these diseases are slow growing with major concerns being that both the variants have malignant transformation capabilities and a high rate of recurrence. In the light of current evidences, it is recommended that MCPM and WDPPM patients should be offered a complete cytoreductive surgery and hyperthermic intraperitoneal chemotherapy consisting of cisplatin and doxorubicin. Collaborative multi-institutional studies are needed to generate more data and formulate robust guidelines.

Peritoneal Mesothelioma in a High Volume Peritoneal Surface Malignancies Unit

Diffuse malignant peritoneal mesothelioma (PM) is a rare neoplasm, traditionally associated with a poor prognosis. There are other varieties of PM that are even less frequent and of uncertain malignancy. Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has achieved prolonged survival in selected patients. The aim of this study is to analyze the patients with PM assessed in our center. Clinicopathological characteristics, diagnostic procedures and survival results from patients with PM appraised at our unit, according to the applied treatment, were analyzed. Seventeen patients were assessed between 2007 and 2019. Three cases had multicystic PM that were treated with complete CRS + HIPEC; all patients are alive and free of disease after a long follow-up. Three other cases had biphasic PM; a curative treatment could be performed in none of them, and their survival was minimal (<6 moths). Lastly, 11 cases with epithelioid PM were treated. Two cases were considered unresectable at laparoscopy (PCI 39); one of them had a long survival (67 months) with three iterative laparoscopic palliatives HIPECs for refractory ascites. The other nine cases were treated with curative CRS + HIPEC, with a median PCI of 14 (range 4–25), and a median overall survival (OS) of 58 months, with a 5-year OS of 47.4%. In conclusion, CRS + HIPEC, when possible, appears to be the optimal treatment for patients with PM. Knowledge of this therapeutic option is crucial, both to offer it to patients and to avoid delays in their referral to appropriate centers for treatment.

Benign multicystic peritoneal mesothelioma mimicking mucinous ovarian neoplasm with pseudomyxoma peritonei

Cystic mesothelioma, also known as benign multicystic peritoneal mesothelioma (BMPM), is a rare neoplasm and one of the five main histological types of peritoneal mesothelioma. Although it is usually considered benign histologically, it is increasingly accepted as a 'borderline malignancy' because the local recurrence rate is high. It is more common in middle-aged women and is generally asymptomatic. Considering that BMPM is often found in the pelvis, it is difficult to differentiate from other pelvic and abdominal lesions, such as cystic ovarian masses, especially mucinous cystadenoma-adenocarcinoma, pseudomyxoma peritonei, etc. Preoperative diagnosis is very difficult due to its rarity and lack of specific diagnostic imaging and clinical findings. Definitive diagnosis is made only by pathological evaluation. In this article, we aimed to present the imaging findings of a BMPM case in a woman who was diagnosed with mucinous ovarian neoplasm with pseudomyxoma peritonei preoperatively and underwent cytoreductive surgery with hyperthermic intraperitoneal chemotherapy.

Impact of centralization of care for malignant peritoneal mesothelioma: A historical cohort study from the Dutch mesothelioma expert centers

BACKGROUND

Malignant peritoneal mesothelioma (MPM) is a rare and aggressive cancer that has a poor prognosis. An earlier population-based study found that the majority of Dutch patients do not receive anti-cancer treatment. In 2015, Dutch Malignant Mesothelioma care was centralized in two expert centers. We reviewed treatment patterns at these centers, to assess the impact of centralization of MPM care in the Netherlands.

METHODS

Data from all patients referred to the Dutch MPM expert centers from 2014 to 2020, were retrospectively collected. Descriptive statistics regarding referrals, patient and tumor characteristics, and treatment patterns were provided. Population-based incidence rates were provided by the Netherlands Cancer Registry.

RESULTS

From 2014 to 2020, 78 patients were referred to the Dutch Mesothelioma expert centers, of whom 32 were female (41%). From 2014 to 2017, 27 patients were referred, whereas 51 patients were referred from 2018 to 2020. This represents about 24% and 61% of the estimated population incidence, respectively. Treatment patterns were comparable between both periods. Between 2014 and 2018, 33% of patients underwent surgery, 44% systemic therapy, and 22% received best supportive care (BSC), while this was 29%, 37%, and 33% respectively from 2018 to 2020.

CONCLUSION

Centralization of care for patients with MPM resulted in an increase of annual referrals to the Dutch mesothelioma expert centers. While population-based incidence did not change during the study period, the absolute number of patients receiving treatment at our centers did increase. This might be considered a first important step towards better treatment for patients with this fatal disease.

Mesotheliomas and Benign Mesothelial Tumors: Update on Pathologic and Imaging Findings

A diverse spectrum of benign entities and malignant neoplasms originate from the monotonous mesothelium that lines the serosal membranes of the pleural, pericardial, and peritoneal cavities. The mesothelium of myriad sites shows a common origin from the lateral plate mesoderm; primary mesothelial tumors thus demonstrate similar pathogenesis, imaging findings, and treatment options. Significant changes have been made in the 2021 World Health Organization (WHO) classification schemata of the pleural and pericardial tumors on the basis of recent advances in pathology and genetics. While malignant mesotheliomas are biologically aggressive malignancies that occur primarily in patients exposed to asbestos with attendant poor survival rates, well-differentiated papillary mesothelial tumors and adenomatoid tumors charter a benign clinical course with an excellent prognosis. Mesothelioma in situ is a newly characterized entity represented by recurrent unexplained pleural effusions without any identifiable mass at imaging or thoracoscopy. Immunohistochemical markers based on BAP1, MTAP, CDKN2A, and TRAF7 gene mutations help differentiate diffuse mesotheliomas from benign mesothelial proliferations and localized mesotheliomas. Cross-sectional imaging modalities, including US, CT, MRI, and fluorine 18-fluorodeoxyglucose (FDG) PET/CT, permit diagnosis and play a major role in staging and assessing surgical resectability. Imaging studies are invaluable in providing noninvasive and quantitative assessment of tumor response in patients with unresectable disease. Owing to significant overlap in patient characteristics and pathomorphology, accurate diagnosis based on advanced histopathology techniques and genetic abnormalities is imperative for optimal management and prognostication. While patients with nonepithelioid pleural mesotheliomas benefit from immunotherapy, novel targeted therapies for CDKN2A-, NF2-, and BAP1-altered mesotheliomas are under consideration. ^© RSNA, 2023 Quiz questions for this article are available through the Online Learning Center.

Diagnostic and Therapeutic Pathway in Diffuse Malignant Peritoneal Mesothelioma

Diffuse malignant peritoneal mesothelioma (DMPM) is a rare form of mesothelioma that carries a very poor prognosis. The 5-year overall survival is about 20% (±5.9). Survival is optimal for patients suitable for cytoreductive surgery (CRS) with Hyperthermic Intraperitoneal Chemotherapy (HIPEC), with a median OS ranging from 34 to 92 months. However, selecting patients for surgery remains a complex task and requires a careful preoperative workup, rational analysis of prognostic profiles, and risk prediction models. Systemic chemotherapy could be offered: (1) in the adjuvant setting for high-risk patients; (2) for patients not eligible for CRS; and (3) for those with recurrent disease. It mainly includes the combination of Platin compound with Pemetrexed or immunotherapy. The biology of DMPM is still largely unknown. However, progress has been made on some fronts, such as telomere maintenance mechanisms, deregulation of apoptosis, tyrosine kinase pathways, and mutation of BRCA1-associated protein 1 (BAP1). Future perspectives should include translational research to improve our understanding of the disease biology to identify druggable targets. We should also clear the role of immune checkpoint inhibitors and investigate new locoregional technologies, such as pressurized intraperitoneal aerosol chemotherapy (PIPAC) or normothermic intraperitoneal chemotherapy (NIPEC).

Malignant peritoneal mesothelioma

Malignant peritoneal mesothelioma (MPM) is a rare, life-threatening malignant tumor. We present a report of a rare case of a 67-year-old male patient with MPM and severe abdominal pain, bloating, and bloody ascites as manifestations. The diagnosis was confirmed by cytology of ascites aspiration fluid and further verified by laparoscopic exploratory biopsy. The characteristics of signs and clinical manifestations in this case are less common. As everyone knows, asbestos exposure is usually associated with pleural mesothelioma, but only 6%-10% of malignant mesothelioma cases originate from the peritoneum, which is far less than pleural mesothelioma. Generally, its non-specificity provides a huge challenge to medical professionals in its diagnosis, and this is also the main reason for delayed diagnosis. Patients should be vigilant, even though no clear risk factor is observed.

Benign Multicystic Peritoneal Mesothelioma Presents as a Tumor in an Elderly Man: An Uncommon Diagnosis

BACKGROUND

Mesotheliomas are benign masses that can arise from any body parts that contain mesothelium, such as the abdominal, pelvic, pleural, and pericardial cavities. Benign multicystic peritoneal mesothelioma is a cystic tumor that arises from peritoneal mesothelial cells. It is a rare pathological entity, as only fewer than 200 cases have been reported. Benign multicystic peritoneal mesothelioma mainly occurs in women, and it is extremely rare in men. Its diagnosis and management are often challenging.

CASE PRESENTATION

This report demonstrates a case of a 61-year-old man who presented to the outpatient clinic with persistent abdominal discomfort that progressed over the years. He had visited different clinics and was referred to a gastroenterologist because of a misdiagnosis. After an extensive clinical evaluation, we failed to provide a definitive diagnosis; thus, diagnostic laparotomy for possible intra-abdominal malignancy was performed. After successful surgical resection of the lesions, the pathology was found compatible with benign multicystic peritoneal mesothelioma.

CONCLUSION

Given its high recurrence rates and potential malignant transformation, meticulous and detailed surgical excision of the cystic lesions is of utmost importance to avoid repeated surgeries. Long-term follow-up is recommended.

Peritoneal disease: key imaging findings that help in the differential diagnosis

The peritoneum is a unique serosal membrane, which can be the site of primary tumors and, more commonly, secondary pathologic processes. Peritoneal carcinomatosis is the most common malignant condition to affect the peritoneal cavity, and the radiologist plays an important role in making the diagnosis and assessing the extent of disease, especially in sites that may hinder surgery. In this review, we address the role of the radiologist in the setting of peritoneal pathology, focusing on peritoneal carcinomatosis as this is the predominant malignant process, followed by revising typical imaging findings that can guide the differential diagnosis.We review the most frequent primary and secondary peritoneal tumor and tumor-like lesions, proposing a systemic approach based on clinical history and morphological appearance, namely distinguishing predominantly cystic from solid lesions, both solitary and multiple.

Acute presentation of multi-cystic peritoneal mesothelioma

Multi-cystic peritoneal mesothelioma (MCPM) is a rare intra-abdominal neoplasm that occurs most commonly in young females. The disease usually presents as an incidental finding or with sub-acute abdominal pain. The mainstay of treatment is complete excision; however, local recurrence frequently occurs and malignant transformation has been reported. We describe a unique case of MCPM that presented with acute abdominal pain.

A 32-year-old female presented with a 24-hour history of abdominal pain. Computed tomography abdomen demonstrated a low-density mass with surrounding inflammatory changes anterior to the ascending colon, which was initially thought to represent an abscess. A percutaneous drain was inserted; however, only clear fluid was aspirated and the lesion did not resolve. The patient subsequently underwent laparoscopy which identified a cystic structure overlying the ascending colon. The structure was excised whole with histology demonstrating MCPM. The patient recovered from surgery and will undergo a period of surveillance.

A rare case of benign multicystic peritoneal mesothelioma misdiagnosed as hydatid cyst found in the liver parenchyma and abdomen cavity of a male with asbestos exposure

Background

Benign Multicystic Peritoneal Mesothelioma (BMPM) is one of the rarest diseases in medicine with only more than 200 cases worldwide. This paper aims to report a case of Benign Multicystic Peritoneal Mesothelioma that strangely arose from the liver and was long treated as Hydatid cyst. The case also had many risk factors including asbestos exposure that had not yet been linked with Benign Multicystic Peritoneal Mesothelioma.

Case presentation

We report a case of a 62 years old male with a history of a perforated peptic ulcer and a cystic mass in the liver that was misdiagnosed as hydatid cyst 7 years ago. He presented with generalized abdominal pain and bloating. Image studies showed many cystic formations filled with clear fluid. An en bloc surgery was performed and a pathologic study showed a multiloculated mass lined by flat or cuboidal epithelium leading to the diagnosis of BMPM. A follow up was scheduled after 3 months revealed total recurrence.

Conclusion

BMPM resembles many other cystic lesions in the abdomen and should be taken into consideration when dealing with nontypical cystic formations. Its diagnostic and treatment methods are still hazy making this disease difficult to approach.

Approach to Cystic Lesions in the Abdomen and Pelvis, with Radiologic-Pathologic Correlation

Cystic lesions found in and around the peritoneal cavity can often be challenging to diagnose owing to significant overlap in imaging appearance between the different entities. When the cystic lesion can be recognized to arise from one of the solid abdominal organs, the differential considerations can be more straightforward; however, many cystic lesions, particularly when large, cannot be clearly associated with one of the solid organs. Cystic lesions arising from the mesentery and peritoneum are less commonly encountered and can be caused by relatively rare entities or by a variant appearance of less-rare entities. The authors provide an overview of the classification of cystic and cystic-appearing lesions and the basic imaging principles in evaluating them, followed by a summary of the clinical, radiologic, and pathologic features of various cystic and cystic-appearing lesions found in and around the peritoneal cavity, organized by site of origin. Emphasis is given to lesions arising from the mesentery, peritoneum, or gastrointestinal tract. Cystic lesions arising from the liver, spleen, gallbladder, pancreas, urachus, adnexa, or soft tissue are briefly discussed and illustrated with cases to demonstrate the overlap in imaging appearance with mesenteric and peritoneal cystic lesions. When approaching a cystic lesion, the key imaging features to assess include cyst content, locularity, wall thickness, and presence of internal septa, solid components, calcifications, or any associated enhancement. While definitive diagnosis is not always possible with imaging, careful assessment of the imaging appearance, location, and relationship to adjacent structures can help narrow the differential diagnosis. Online supplemental material is available for this article. ^©RSNA, 2021.

Multicystic peritoneal mesothelioma treated with cytoreductive surgery followed or not by hyperthermic intraperitoneal chemotherapy: results from a large multicentric cohort

BACKGROUND

Multicystic peritoneal mesothelioma (MCPM) is a rare, slowly growing, condition prone to recur after surgery. The role of hyperthermic intraperitoneal chemotherapy (HIPEC) added to complete cytoreductive surgery (CRS) remains controversial and difficult to assess. As patients are mostly reproductive age women, surgical approach, and fertility considerations are important aspects of the management. This observational retrospective review aimed to accurate treatment strategy reflections.

METHODS

The RENAPE database (French expert centers network) was analyzed over a 1999-2019 period. MCPM patients treated with CRS were included. A special focus on HIPEC, mini-invasive approach, and fertility considerations was performed.

RESULTS

Overall 60 patients (50 women) were included with a median PCI of 10 (4-14) allowing 97% of complete surgery, followed by HIPEC in 82% of patients. A quarter of patients had a laparoscopic approach. Twelve patients (20%) recurred with a 3-year recurrence free survival of 84.2% (95% confidence interval 74.7-95.0). The hazard of recurrence was numerically reduced among patients receiving HIPEC, however, not statistically significant (hazard ratio 0.41, 0.12-1.42, p = 0.200). A severe post-operative adverse event occurred in 22% of patients with five patients submitted to a subsequent reoperation. Among four patients with a childbearing desire, three were successful (two had a laparoscopic-CRS-HIPEC and one a conventional CRS without HIPEC).

CONCLUSION

MCPM patients treatment should aim at a complete CRS. The intraoperative treatment options as laparoscopic approach, fertility function sparing and HIPEC should be discussed in expert centers to propose the most appropriate strategy.

Multicystic peritoneal mesothelioma treated with complete cytoreductive surgery, peritonectomy and hyperthermic intra-peritoneal chemotherapy-A case report

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Multicystic Peritoneal mesothelioma is a distinct type of peritoneal mesothelioma with borderline malignant potential and tendency to recur after tumor debulking.

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Morphologically MCPM has grapelike cysts filled with clear fluid and microscopically it has cystic spaces lined by cuboidal epithelium.

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There are areas of increased proliferative activity in the background of benign cyst representing potential for aggressiveness.

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Peritoneal free floating cysts can be formed from disintegration of main mass and deposit in other areas to form metastatic deposits.

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Comprehensive treatment – Complete cytoreduction, involved peritonectomy and HIPEC is required for treatment of macroscopic tumor and microscopic residue.

Background

Multicystic Peritoneal mesothelioma is a rare and distinct variety of peritoneal mesothelioma with borderline malignant potential. Conventional Tumor bulking has been associated with recurrence of 45–50 %. Hence a comprehensive treatment with Complete cytoreductive surgery with involved field peritonectomy (CRS) and Hyperthermic Intra-peritoneal chemotherapy (HIPEC) is being increasingly adopted for MCPM.

Case presentation

A 47 year old lady evaluated for peri-menopausal disturbance was diagnosed to have a multicystic lesion in the pelvis. With a preoperative suspicion of diagnosis of pseudomyxoma peritonei, CRS with HIPEC was planned. On exploration a diffuse multicystic mass was found in omentum and pouch of douglas with typical morphological features of MCPM. Complete cytoreduction was achieved with anterolateral and sub-diaphragmatic peritonectomy, omentectomy and panhystrectomy. HIPEC was performed with cisplatin 50 mg/m² for 40 min. Pathological examination revealed MCPM of omentum and uterine surface with focal clusters of mesothelial proliferation. However there was low proliferative activity 1–2 %.

Discussion

MCPM presents with wide spread peritoneal spread but with relative sparing of visceral invasion. Literature review suggests the disease spread is similar to PMP and treatment with CCRS and HIPEC has yielded long term survivals in MCPM.

Conclusions

This patient with voluminous disease burden in abdomen required surgical management and HIPEC for her condition. Whether CCRS alone without HIPEC can be an alternative for limited disease will be interesting research for future clinical reports.