Well-differentiated papillary mesothelioma of the tunica vaginalis: Case report and literature review

Testicular/paratesticular mesothelial tumours: Uncommon histopathologic entities in a very complex anatomical site

Mesothelial tumours of the testicular/paratesticular region are uncommon, poorly characterised and difficult-to-diagnose lesions. They encompass entirely benign proliferations (adenomatoid tumour) and malignant, very aggressive tumours (mesothelioma) whose morphological features can be overlapping, highly variable and confounding. Moreover, testicular/paratesticular mesothelial tumours comprise relatively new entities with indolent behaviour (well-differentiated papillary mesothelial tumour) as well as tumours which cannot be correctly included in any of the aforementioned categories and whose classification is still controversial. The molecular profile of such tumours represents an open issue. In fact, despite the recent discoveries about the genomic landscape of mesothelial proliferations at other sites (pleura, peritoneum), testicular/paratesticular mesothelial tumours, and namely mesotheliomas, are too rare to be extensively studied on large case series and they could arguably hide relevant differences in their molecular background when compared to the more common pleural/peritoneal counterparts.The aim of this review is to provide a guide for the pathological assessment of testicular/paratesticular mesothelial tumours. Herein, we describe the most recent updates on this topic according to the latest (year 2022) World Health Organisation Classification of Urinary and Male Genital Tumours (5th edition) and current literature. The diagnostic criteria, the main differentials and the role of ancillary techniques in the diagnosis of mesothelial testicular/paratesticular tumours are discussed.

Well differentiated papillary mesothelioma of the tunica vaginalis: case report

Well differentiated papillary mesothelioma (WDPM) is a rare entity making up 0.3-5% of all mesothelioma cases, while manifestations of the tunica vaginalis are even more uncommon. Literature on WDPM is scarce and our understanding is rather limited. Cellular architecture, stromal invasion, mitotic activity and immunohistochemical markers are used to distinguish well differentiated entities from more malignant subspecies. These cases confront both pathologists and clinicians with a hefty diagnostic challenge. Although no paratesticular WDPM specific mortality has been reported, the prognosis of a malignant mesothelioma is very poor. A correct diagnosis is therefore of the utmost importance. In this paper we provide an overview on the diagnosis and differentiation of mesotheliomas of the tunica vaginalis. Furthermore, we highlight pitfalls and build up a recommended therapeutic strategy.

Mesothelioma of the tunica vaginalis testis: A case report

Primary mesotheliomas of the tunica vaginalis testis are very rare malignant tumors. They are generally associated with exposure to asbestos. They may manifest as hydrocele, testis tumor, inguinal hernia, or epididymitis. After differential diagnosis, treatment is primarily surgical. Adjuvant therapeutic methods for mesotheliomas of the tunica vaginalis testis, with their high mortality, are controversial. Here, we present a mesothelioma case derived from tunica vaginalis testis acting as long-term pyocele with no known asbestos exposure.

Clinicopathological Characteristics of Well-differentiated Papillary Mesothelioma of The Peritoneum: A Single-institutional Experience of 12 Cases

BACKGROUND/AIM

Well-differentiated papillary mesothelioma (WDPM) is histologically characterized by papillary architecture with fibrovascular cores, lined by bland mesothelial cells. We recently experienced a case of WDPM associated with multiple peritoneal inclusion cysts, which prompted us to initiate a comprehensive review of previously diagnosed WDPM cases.

MATERIALS AND METHODS

The clinicopathological characteristics and immunophenotype of 12 cases of peritoneal WDPM were investigated using a review of electronic medical records, pathological examination, and immunostaining.

RESULTS

The patients' ages ranged from 23 to 75 years. No patient had endometriosis or a previous history of asbestos exposure. Ten tumors were detected incidentally during surgery for other causes. Most tumors appeared as a small, single nodule on the peritoneal surface, but in three cases, WDPM presented as multiple lesions. All but one patient had no symptoms. All the patients examined are still well without postoperative recurrence. Histologically, all cases demonstrated typical papillary architecture with fibrovascular cores. The mesothelial cells lining the papillae consisted mostly of single row of cells, although areas of proliferation to multiple layers were observed in a few cases. Their nuclei appeared bland, but two cases exhibited mild nuclear atypia and prominent nucleoli. Immunostaining revealed that the mesothelial cells were positive for D2-40, cytokeratin 5/6, cytokeratin 7, and Wilms' tumor 1.

CONCLUSION

We herein demonstrated the clinicopathological characteristics of peritoneal WDPMs. WDPM has distinct pathological features. Although all cases we examined were uneventful after surgery, further surveillance is recommended since the biological behavior of WDPM is still uncertain.

Testicular Mesothelioma: An Analysis of Epidemiology, Patient Outcomes, and Prognostic Factors

OBJECTIVES

To characterize demographic features, clinical characteristics, and oncologic outcomes of mesothelioma of the testis.

METHODS

A population based search was performed using the National Cancer Institute's SEER 18 database. Patients diagnosed with malignant mesothelioma of the male genital organs from 1973 to 2015 were identified. Data on patient age, race, tumor laterality, histologic subtype, tumor extent, tumor size, tumor grade, treatment, cause of death, and survival months was collected. Primary outcomes were overall survival (OS) and disease-specific survival (DSS).

RESULTS

A total of 113 patients with testicular mesothelioma were identified. The 5-year OS and DSS for all patients was 49% and 58%, and the 10-year OS and DSS was 33% and 45%, respectively. Biphasic mesotheliomas were associated with worse OS compared to general mesotheliomas and epithelioid subtypes (P = .043 and P = .039, respectively). Median survival time was not reached in patients with T1 disease while OS was 1.7 years and DSS was 1.8 years for patients with T4 disease (OS P = .002, DSS P <.001). Tumors greater than or equal to 4 cm were associated with worse OS and DSS (OS P = .025, DSS P = .047).

CONCLUSION

This rare malignancy has significant mortality, with poor survival associated with biphasic subtypes, higher disease stage, and a critical tumor size cutoff of 4 cm.