Therapeutic strategies for well-differentiated papillary mesothelioma of the peritoneum

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.

Targeting Oncometabolites in Peritoneal Cancers: Preclinical Insights and Therapeutic Strategies

Peritoneal cancers present significant clinical challenges with poor prognosis. Understanding the role of cancer cell metabolism and cancer-promoting metabolites in peritoneal cancers can provide new insights into the mechanisms that drive tumor progression and can identify novel therapeutic targets and biomarkers for early detection, prognosis, and treatment response. Cancer cells dynamically reprogram their metabolism to facilitate tumor growth and overcome metabolic stress, with cancer-promoting metabolites such as kynurenines, lactate, and sphingosine-1-phosphate promoting cell proliferation, angiogenesis, and immune evasion. Targeting cancer-promoting metabolites could also lead to the development of effective combinatorial and adjuvant therapies involving metabolic inhibitors for the treatment of peritoneal cancers. With the observed metabolomic heterogeneity in cancer patients, defining peritoneal cancer metabolome and cancer-promoting metabolites holds great promise for improving outcomes for patients with peritoneal tumors and advancing the field of precision cancer medicine. This review provides an overview of the metabolic signatures of peritoneal cancer cells, explores the role of cancer-promoting metabolites as potential therapeutic targets, and discusses the implications for advancing precision cancer medicine in peritoneal cancers.

The role of imaging in diagnosis and management of malignant peritoneal mesothelioma: a systematic review

PURPOSE

Imaging of the peritoneum and related pathology is a challenge. Among peritoneal diseases, malignant peritoneal mesothelioma (MPeM) is an uncommon tumor with poor prognosis. To date, there are no specific guidelines or imaging protocols dedicated for the peritoneum and MPeM. The objective of this study was to analyze the literature describing imaging modalities used for MPeM to determine their relative clinical efficacy and review commonly reported imaging features of MPeM to promote standardized reporting.

METHODS

We performed a systematic review of original research articles discussing imaging modalities in MPeM from 1999 to 2020. Effectiveness measures and common findings were compared across imaging modalities.

RESULTS

Among 582 studies analyzed, the most-used imaging modality was CT (54.3%). In the differentiation of MPeM from peritoneal carcinomatosis, one study found CT had a diagnostic sensitivity of 53%, specificity of 100%, and accuracy of 68%. Two studies found fluorodeoxyglucose positron emission tomography (FDG-PET) had sensitivity of 86-92%, specificity of 83-89%, and accuracy of 87-89%. Another study found magnetic resonance imaging (MRI) was the best predictor of the peritoneal carcinomatosis index. Characteristics shown to best differentiate MPeM from other diseases included ascites, peritoneal thickening, mesenteric thickening, pleural plaques, maximum tumor dimension, and number of masses.

CONCLUSION

Most published MPeM imaging studies utilized CT. PET/CT or MRI appear promising, and future studies should compare effectiveness of these modalities. MPeM imaging reports should highlight ascites, number of and maximum tumor dimension, peritoneal/mesenteric thickening, and associated pleural plaques, allowing for better aggregation of MPeM imaging data across studies.

Well-differentiated papillary mesothelioma found incidentally with concurrent struma ovarii: A case report

This is the first report of well-differentiated papillary mesothelioma (WDPM) found concurrently with struma ovarii. These rare tumors have no know association, and are considered benign, though malignant transformation of WDPM has been described. After treatment of WDPM, follow-up surveillance has been suggested in the literature, though a method has not been described and an evidence base is lacking. Pre-operative imaging by computed tomography and ultrasound did not identify the WDPM, calling into question the role of imaging-based follow-up. Furthermore, malignant transformation has been reported only outside of the typical 5-year follow-up window. The authors of this case report suggest rationalization of follow-up of WDPM, acknowledging the risks and unknown harms of scheduled imaging follow-up.

Peritoneal well-differentiated papillary mesothelioma coexisting with endometrial adenocarcinoma mimicking peritoneal carcinomatosis: A case report

OBJECTIVE

We present a rare case of well-differentiated papillary mesothelioma (WDPM) found incidentally in a 59-year-old woman with endometrial cancer.

CASE REPORT

A 59-year-old nulliparous obese woman with a past history of hypertension and diabetes mellitus presented with postmenopausal bleeding for 11 months. Two months prior to this admission, an episode of massive vaginal bleeding lasting for a day was noticed by the patient. Hysteroscopy was performed after her visit to our outpatient department. Papillary tumors with active bleeding were found in the uterine cavity. Endometrial biopsy showed adenocarcinoma, endometrioid type characterized by papillary architecture lined by columnar cells with mild nuclear pleomorphism. The patient proceeded to magnetic resonance imaging (MRI), which demonstrated a 6.4 × 5.5 × 4.9 cm intrauterine mass. Her tumor marker levels were elevated (CA 125 87.8 IU/ml, CA19-9160.54 IU/ml). The patient then underwent a staging surgery and final pathology revealed stage IA endometrial cancer. During surgery, multiple nodules were found in the peritoneum, initially considered as tumor metastasis and eventually proved to be WDPM.

CONCLUSION

In conclusion, the simultaneous occurrence of WDPM with endometrial cancer is a rare entity. Although no standardized treatment has been established, WDPMs have a relatively favorable prognosis compared to malignant mesotheliomas.

Peritoneal well-differentiated papillary mesothelioma associated with infertility in a 37-year-old woman

Well-differentiated papillary mesothelioma (WDPM) is an uncommon mesothelial tumor. The lesions may be single or multiple and usually behave in a benign or indolent fashion, sometimes persisting for many years. In the present case, a 37-year-old woman had experienced primary infertility for 12 years, and a diagnostic laparoscopy was performed. Approximately 200 mL of dark red, free fluid in the pelvis and more than 10 yellow-white nodules on the surface of the right round ligament, sacrum ligament, right fallopian tube, and both sides of the uterus were found. A lesionectomy was performed and immunohistochemical markers indicated WDPM with adenomatoid tumor. The patient was monitored by computed tomography and serum CA125 (cancer antigen 125) levels for 49 months with no recurrence. WDPM and adenomatoid tumor are both benign tumors of mesothelial origin. Because of the lack of effective radical treatment, regular follow-up is sufficient. However, the effects of estrogen and progesterone on WDPM and adenomatoid tumors during ovulation or pregnancy remains unclear. Although WDPM is not life threatening, a strategy to fulfill the fertility requirements of women with this condition is a new challenge for infertility doctors.

Spontaneous urinary bladder perforation: An unusual presentation of well-differentiated papillary peritoneum mesothelioma

INTRODUCTION

Well-differentiated papillary mesothelioma (WDPM) is a very rare neoplasm. Most of WDPM are asymptomatic and are often incidentally detected during surgery. This report describes a case of WDPM of the peritoneum unexpectedly diagnosed in a male with a spontaneous intraperitoneal bladder rupture.

CASE PRESENTATION

A 65-year-old male presented to our Emergency Department in November 2019 with a two-day history of anuria, abdominal pain, distention, and sepsis. The CT scan reported a large amount of extra and intraperitoneal free fluid. The CT cystogram showed bladder perforations on the dome and on the left lateral wall which was repaired through exploratory laparotomy. Intraoperatively, we encountered extensive suppurative peritonitis with large fibrino-purulent exudation. The purulent perivesical peritoneum was dissected and sent for histopathological examination which unexpectedly resulted in WDPM of the peritoneum.

CONCLUSION

Although we can't affirm with certainty, this case would seem to suggest that WDPM had played a role in patient's clinical presentation. However, further research is necessary to draw stronger conclusion.

Well-Differentiated Papillary Mesothelioma With Two Synchronous Serous Gynaecologic Carcinomas in a 62-Year-Old Woman: Lessons Learned for the Gynaecologic Surgeon

BACKGROUND

Well-differentiated papillary mesothelioma (WDPM) is a rare tumor of unknown malignant potential. It is typically diagnosed incidentally during benign gynaecologic surgery. We report the first published case of WDPM in a woman with synchronous serous carcinomas of the gynaecologic tract and highlight lessons learned for general gynaecologists and gynaecologic oncologists alike.

CASE

A 62-year-old woman was referred for assessment and management of a pelvic mass. Intraoperatively, metastatic high-grade carcinoma was identified and the patient underwent a successful debulking procedure that identified 3 synchronous tumors: ovarian high-grade serous carcinoma, endometrial serous carcinoma, and 2 foci of pelvic WDPM.

CONCLUSION

This case of WDPM with 2 synchronous serous gynaecologic tumors is a novel addition to the reported literature and offers many learning points about the disease. Gynaecologic surgeons should be familiar with WDPM, as it is predominantly found in reproductive-aged women undergoing benign gynaecologic surgery, may be linked with endometriosis, and has an unclear malignant potential. Multidisciplinary care is essential for accurate diagnosis. Further research is needed to clarify the optimal management and surveillance of WDPM.

Acute severe abdominal pain in a young woman caused by a well-differentiated papillary mesothelioma of the peritoneum

Acute abdominal pain is a common symptom in young women. We describe a patient with acute illness and severe lower abdominal pain. Laboratory tests were normal except for mildly deranged inflammatory markers. No abnormalities were reported on abdominal ultrasonography and MRI, whereas diagnostic laparoscopy revealed a tumour located dorsally from the uterus. We resected the tumour and pathology results showed a well-differentiated papillary mesothelioma of the peritoneum (WDPMP). Microscopy showed evidence of acute ischaemia in the resected lesion, which was likely the cause of the acute abdominal pain. WDPMP is a rare disease that arises from the serous membranes which does not seem to have a relation to asbestos exposure. Generally, WDPMP has a mild clinical course and good long-term prognosis.

Synchronous presentation of muscle-invasive urothelial carcinoma of bladder and peritoneal malign mesothelioma

Introduction

Cancer is one of the most important leading cause of death in man and woman in the world. The occurrence of new cancer has become more frequent in recent years due to strict screening protocols and occupational and environmental exposure to carcinogens. The incidence of secondary malignancies has also increased due to close medical follow-up and advanced age. Herein, we report a case and its management diagnosed as synchronous peritoneal malignant mesothelioma and muscle-invasive urothelial carcinoma.

Case Description

A 71-year-old male presented with macroscopic hematuria and abdominal distension increasing gradually. A contrast enhanced computerized tomography demonstrated bladder mass and diffuse ascites with nodular peritoneal thickening and umbilical mass. He was treated with the multidisciplinary team working including urologist, medical oncologist and general surgeon.

Conclusions

To our knowledge, this is the first case of peritoneal malign mesothelioma with synchronous muscle-invasive urothelial carcinoma. Because of the rarity of this condition, there is still no consensus on the definitive treatment protocols, yet. Individualized treatment with multidisciplinary close follow-up might improve the survival outcomes.

Well-Differentiated Papillary Mesothelioma of the Peritoneum: A Retrospective Study from the RENAPE Observational Registry

BACKGROUND

Well-differentiated papillary mesothelioma of the peritoneum (WDPMP) is a rare entity. Questions regarding management are still being debated as no more than 50 cases have been reported in the literature.

OBJECTIVE

We aimed to analyze the clinical, therapeutic, and prognostic data of patients with WDPMP from the RENAPE observational registry.

PATIENTS AND METHODS

All patients diagnosed with WDPMP and prospectively included in the RENAPE national registry between 2010 and 2018 were also included in our study. Expert pathologists from the RENA-PATH group confirmed all cases. All clinical, therapeutic, postoperative, and prognostic data were extracted and analyzed.

RESULTS

We report on 56 patients with a mean age of 52 years (range 21-74). WDPMP was incidentally diagnosed during imaging or surgery in 16% and 36% of patients, respectively, and an association with synchronous malignancy was found in 18% of patients. Nine lesions showed discrete signs of fatty invasion. The median Peritoneal Cancer Index was 11 (range 0-33). Eleven patients were treated with definitive excision, 4 were treated with cytoreductive surgery (CRS) only, 37 were treated with CRS and hyperthermic intraperitoneal chemotherapy (HIPEC), and 2 were treated with CRS plus HIPEC plus early postoperative intraperitoneal chemotherapy. CRS was considered to be complete in 90% of cases. One patient died postoperatively and 16 patients (31%) faced postoperative complications. The median disease-free survival was 144 months; Four patients relapsed, with a median period of 27 months. No prognostic factors could be identified.

CONCLUSIONS

Our analysis confirms the favorable prognosis of WDPMP. CRS and HIPEC could be a therapeutic option for diffuse, symptomatic, and/or recurrent disease.

Well-differentiated papillary mesothelioma of the peritoneum is genetically defined by mutually exclusive mutations in TRAF7 and CDC42

Well-differentiated papillary mesothelioma is an uncommon mesothelial neoplasm that most frequently arises in the peritoneal cavity of women of reproductive age. Whereas malignant mesothelioma is an aggressive tumor associated with poor outcome, well-differentiated papillary mesothelioma typically exhibits indolent behavior. However, histologically differentiating between these two entities can be challenging, necessitating the development of distinguishing biomarkers. While the genetic alterations that drive malignant mesothelioma have recently been determined, the molecular pathogenesis of well-differentiated papillary mesothelioma is unknown. Here we performed genomic profiling on a cohort of ten well-differentiated papillary mesothelioma of the peritoneum. We identified that all tumors harbored somatic missense mutations in either the TRAF7 or CDC42 genes, and lacked alterations involving BAP1, NF2, CDKN2A, DDX3X, SETD2, and ALK that are frequent in malignant mesothelioma. We recently identified that another mesothelial neoplasm, adenomatoid tumor of the genital tract, is genetically defined by somatic missense mutations in the TRAF7 gene, indicating a shared molecular pathogenesis between well-differentiated papillary mesothelioma and adenomatoid tumors. To the best of our knowledge, well-differentiated papillary mesothelioma is the first human tumor type found to harbor recurrent mutations in the CDC42 gene, which encodes a Rho family GTPase. Immunohistochemistry demonstrated intact BAP1 expression in all cases of well-differentiated papillary mesothelioma, indicating that this is a reliable marker for distinguishing well-differentiated papillary mesothelioma from malignant mesotheliomas that frequently display loss of expression. Additionally, all well-differentiated papillary mesothelioma demonstrated robust expression of L1 cell adhesion molecule (L1CAM), a marker of NF-kB pathway activation, similar to that observed in adenomatoid tumors. In contrast, we have previously shown that L1CAM staining is not observed in normal mesothelial cells and malignant mesotheliomas of the peritoneum. Together, these studies demonstrate that well-differentiated papillary mesothelioma is genetically defined by mutually exclusive mutations in TRAF7 and CDC42 that molecularly distinguish this entity from malignant mesothelioma.

Well-differentiated papillary mesothelioma: A 17-year single institution experience with a series of 75 cases

We present our experience with 75 cases of well-differentiated papillary mesothelioma (WDPM) that were diagnosed at our institution between 2000 and 2017. The patients included 58 females and 17 males with age ranging from 18 to 69 years (mean, 42 years). Clinically, the vast majority of WDPMs were incidental findings during laparotomy or laparoscopic surgery for a variety of benign or malignant disease. The lesion manifested as either a small solitary nodule or multiple miliary nodules on the peritoneum or serosal surfaces of internal organs. Histologically, 67 cases were consistent with a classical WDPM, of which 6 cases contained microinvasive foci and 1 case had malignant transformation. Eight cases were hybrid tumors with variable combined component of adenomatoid tumor (n = 4), multicystic mesothelioma (n = 2), and both (n = 2). By immunohistochemistry, besides calretinin, D2-40, CK5/6 and WT1, 94% (29/31) of cases also showed immunostaining for PAX8. In comparison, PAX8 staining was only present in 12% (6/50) of epithelioid malignant mesothelioma selected as control cases. Follow-up information available in 46 cases revealed no signs of tumor progression or local recurrence except for the case that showed transformation to a fully malignant mesothelioma after a period of 15 years. Our comprehensive study further expanded the clinical and histopathological spectrum of WDPM. Compared with epithelioid malignant mesothelioma, PAX8 staining is highly sensitive and specific for WDPM (P < 0.001).

Challenging and uncommon diagnosis of long-evolution ascites

This is a case report of a 45-year-old Caucasian man with chronic alcoholism. No history of liver disease or asbestos exposure. He complained of ascites during the last 3 years with worsening in the last year with severe ascites development. Diagnostic paracentesis showed SAAG 1.1 and high cellularity with neutrophil count >250 cells/µL. Ascitic fluid cytology revealed reactive mesothelial hyperplasia. Thoracoabdominopelvic ultrasonography/CT/MRI and fludeoxyglucose positron emission tomography/CT showed 'omental cake' pattern suggesting peritoneal carcinomatosis. An exploratory laparoscopy revealed moderate interloop adhesions and necrosis with whitish exudate in the right pelvic excavation. Biochemical/cytological/histological/microbiological study only revealed reactive mesothelial cells, necrosis and lymphohistiocytic inflammatory infiltrate. A second exploratory laparoscopy with liver and peritoneal biopsies and appendectomy/mesoappendix excision showed a well-differentiated tubulopapillary mesothelioma. The patient was referred for intraperitoneal chemotherapy and is undergoing monthly therapeutic paracentesis.

A Case of Well-Differentiated Papillary Mesothelioma of the Male Peritoneum: Successful Treatment by Systemic Chemotherapy

Well-differentiated papillary mesothelioma of the peritoneum (WDPMP) is a rare subtype of epithelioid mesothelioma, which is usually seen in young women without a history of asbestos exposure, and generally, has an indolent course. The relative rarity of this neoplasm in males prompted us to report this case of a well-differentiated papillary mesothelioma of the peritoneum in a 36-year-old man.

The patient, who had no history of asbestos exposure, presented with abdominal pain and ascites of unknown etiology. Computed tomography showed abundant ascites with nodules of the peritoneal cavity. Laparoscopic examination revealed a large number of white miliary nodules diffusely covering the peritoneum. Pathology revealed a diagnosis of well-differentiated papillary mesothelioma of the peritoneum, based on histomorphology and immunohistochemistry. The patient started chemotherapy with cisplatin and pemetrexed. After six cycles of chemotherapy, the effectiveness of this chemotherapy was checked by only the computed tomography. PET scan was not used because it is not routinely recommended in WDPMP. Few data are currently available in the literature regarding the performance of the PET scan in WDPMP. Nine months later, the patient was free of symptoms.

Based on reviewing the literature and our observations in this case, consultation of other pathologists is highly recommended to discern WDPMP from other disseminated peritoneal diseases, in order to offer the most effective and safe therapeutic strategy. Chemotherapy should be strongly considered if the tumor is unresectable and accompanied by symptoms. Cisplatin and pemetrexed chemotherapy could be a promising therapeutic choice.

Incidental finding of multiple well-differentiated papillary mesotheliomas in peritoneum

We present a case of multiple well-differentiated papillary mesotheliomas (WDPM) in the peritoneum found incidentally in a 63-year-old man with urothelial carcinoma of the bladder. When multiple tumors are seen, malignant mesothelioma should be excluded by histopathological examination as this may have a similar focal appearance to WDPM. True stromal invasion is by far the most reliable criterion of mesothelial malignancy. In doubtful cases, a conservative diagnostic approach has been recommended. Compared to malignant mesotheliomas, WDPMs are rare and have a relatively indolent clinical course with a good prognosis. Great care is needed when diagnosing mesothelial proliferations, given the crucial nature of a benign vs malignant diagnosis. No standardized treatment has yet been established.