Peritoneal Mesothelioma-An Update

Malignant Para-Testicular Mesothelioma: A Rare Presentation in the Tunica Vaginalis of an Elderly Male With No Prior Asbestos Exposure

Malignant mesothelioma of the tunica vaginalis is an extremely rare and aggressive tumor that is frequently encountered in elderly patients. The diagnosis of malignant mesothelioma of the tunica vaginalis poses a diagnostic challenge due to its infrequency and nonspecific clinical presentation. Histopathological examination and immunohistochemical staining are essential in differentiating this tumor from other para-testicular masses and establishing a definitive diagnosis. Early detection and comprehensive treatment planning are crucial for improving the prognosis and overall outcomes for patients with this rare malignancy. We present a report of malignant mesothelioma of the tunica vaginalis in a 78-year-old male patient with no history of asbestos exposure who presented with a large infiltrative left para-testicular mass. Histopathological examination revealed a biphasic proliferation composed of epithelioid and spindle cells with infiltrative features, foci of necrosis, and increased mitotic figures. Immunohistochemical staining exhibited positive staining for WT1, D2-40, and calretinin, supporting the mesothelial origin of the tumor. Notably, BerEP4 staining was negative, arguing against carcinoma. Immunostaining for keratin 5 was positive, supporting the mesothelial differentiation. The Ki67 proliferation index was high. The differential diagnosis included adenomatoid tumors, germ cell tumors, and pleomorphic sarcoma. We aim to discuss the clinical presentation, diagnostic approach, and therapeutic approaches of this rare entity.

Female Adnexal Tumor of Probable Wolffian Origin (Wolffian Tumor): A Potential Mimic of Peritoneal Mesothelioma

Wolffian tumor and its nosologic relative, the recently defined STK11 adnexal tumor are rare neoplasms thought to arise from mesonephric remnants. These tumors typically arise in the broad ligament, fallopian tube, and ovarian hilum and although most are associated with a good prognosis, up to 50% of STK11 adnexal tumors demonstrate aggressive clinical behavior. The chief differential diagnoses include endometrioid adenocarcinoma and sex cord stromal tumors. However, the morphologic and immunohistochemical features of these tumors exhibit considerable overlap with peritoneal mesothelioma. To fully characterize their immunophenotypic signature, we examined a total of 21 cases (18 Wolffian and 3 STK11 adnexal tumors) with standard markers used in the diagnosis of mesothelioma. Morphologic and immunohistochemical (IHC) features were reviewed and additional IHC performed for cases with available material. Patient age ranged from 25 to 73 (mean: 51) years. Sites included adnexa/broad ligament (6, 28%), paratubal (5, 24%), ovary/paraovarian (5, 24%), tubal (intraluminal) (2, 9.5%), pelvis (2, 9.5%), and liver (1, 5%). The mean tumor size was 9.3 cm (range: 0.2 to 22 cm). The histomorphology in most cases (14/21, 66%) consisted of tubular to solid sheets of neoplastic cells lined by columnar to cuboidal cells containing uniform round to oval nuclei. Compressed tubules with slit-like lumens and sieve-like pattern were also seen in at least 7 (33%) cases. Three cases demonstrated interanastomosing cords and trabeculae of epithelioid cells with cribriform and microacinar patterns growing within prominent myxoid stroma as described in STK11 adnexal tumors. In the cases with available IHC for 3 mesothelial markers (calretinin, WT1, D2-40), 55.5% (5 of 9) showed reactivity with all 3 markers. In cases with at least 2 available mesothelial markers, 69% (11/16) were positive for 2 markers (mostly calretinin and WT1). Claudin-4, MOC31, and BER-EP4 were negative in most cases tested (78% [7/9], 71.4% [5/7], and 100% [6/6], respectively). Given the resemblance to mesothelioma, there was initial strong consideration and/or actual misdiagnosis of mesothelioma in 3 cases (14%). In summary, the morphologic and immunohistochemical features of Wolffian tumor and its recently defined relative, STK11 adnexal tumor, can lead to misdiagnosis of mesothelioma, particularly when encountered in the disseminated or metastatic setting. Wolffian tumor and STK11 adnexal tumor should be considered in the differential diagnosis of all pelvic and peritoneal mesotheliomas.

Risk factors and prognosis of malignant peritoneal mesothelioma with paraneoplastic syndrome

BACKGROUND

Malignant peritoneal mesothelioma (MPM) is a rare and highly aggressive tumor. Its clinical manifestations are diverse, and the symptoms are not specific. Some patients will develop paraneoplastic syndrome (PS) during the disease course. This study aims to analyze the risk factors of PS in patients with MPM and their impacts on prognosis.

METHODS

The clinical data of MPM patients who underwent cytoreductive surgery plus hyperthermic intraperitoneal chemotherapy (CRS + HIPEC) at our center from June 2015 to May 2023 were retrospectively analyzed. MPM patients were divided into PS group and non-PS group according to the diagnostic criteria. Univariate and multivariate analyses were performed to explore the risk factors of PS in MPM patients, and to analyze the impact of PS on prognosis.

RESULTS

There were 146 MPM patients in this study, including 60 patients (41.1%) with PS and 86 patients (58.9%) without PS. The highest incidence of PS was thrombocytosis (33.6%), followed by neoplastic fever (9.6%). Univariate analysis revealed 8 factors (P < 0.05) with statistically significant differences between the two groups: prior surgical scores, targeted therapy history, Karnofsky performance status score, preoperative carbohydrate antigen (CA) 125 level, vascular tumor embolus, peritoneal cancer index, completeness of cytoreduction (CC) score and intraoperative ascites. Multivariate analysis identified 3 independent factors associated with PS: preoperative CA 125 level, vascular tumor embolus, and CC score. Survival analysis demonstrated that MPM patients with PS had worse prognosis, although PS was not an independent prognostic factor.

CONCLUSIONS

PS is not rare in patients with MPM, and is independently associated with preoperative CA 125 level, vascular tumor embolus and CC score. PS often indicates advanced disease and poor prognosis.

Malignant Peritoneal Mesothelioma: An In-Depth and Up-to-Date Review of Pathogenesis, Diagnosis, Management and Future Directions

Malignant peritoneal mesothelioma (MPM) is an extremely rare malignancy usually confined to the abdominal cavity. With an aggressive natural history, morbidity and mortality are consequences of progressive locoregional effects within the peritoneal cavity. The first reported case was in the early 20th century, however, due to the rare nature of the disease and a large gap in understanding of the clinicopathological effects, the next reported MPM cases were only published half a decade later. Since then, there has been exponential growth in our understanding of the disease, however, there are no prospective data and a paucity of literature regarding management. Traditionally, patients were treated with systemic therapy and the outcomes were very poor, with a median survival of less than one year. However, with the advent of cytoreductive surgery and locoregional chemotherapy, there have been significant improvements in survival. Even more recently, with an improved understanding of the molecular pathogenesis of MPM, there have been reports of improved outcomes with novel therapies. Given the disastrous natural history of MPM, the limited data, and the lack of universal treatment guidelines, an in-depth review of the past, present, and future of MPM is critical to improve treatment regimens and, subsequently, patient outcomes.