Malignant mesothelioma of the tunica vaginalis testis: diagnostic studies and differential diagnosis

Our plain-English summary of Malignant mesothelioma of the tunica vaginalis testis: diagnostic studies and differential diagnosis, by S.S. Chekol, C.C. Sun (Archives of Pathology & Laboratory Medicine, 2012).

The study

• Authors: S.S. Chekol, C.C. Sun
• Journal: Archives of Pathology & Laboratory Medicine
• Published: 2012;136(1):113-7
• Type of article: Review
• Cited by: 59 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Malignant mesothelioma of the tunica vaginalis testis is an extremely rare tumor representing 0.3% to 5% of all malignant mesotheliomas. Gross examination of testicular mesotheliomas typically reveals tumor nodules studding the thickened tunica vaginalis and, in some cases, infiltrating the testicular parenchyma, leading to diagnostic challenges. Microscopically, the tumor is characterized by epithelioid cells arising from the tunica vaginalis with papillary, tubulopapillary, or solid architectural patterns. The papillae are usually lined by a single layer of cells with relatively bland cytologic features. An epithelial cell phenotype admixed with a sarcomatoid pattern has also been described in a few cases. Immunohistochemically, the tumor is usually positive for calretinin, Wilms tumor-1, epithelial membrane antigen, D2-40, thrombomodulin, cytokeratin 7, and cytokeratin 5/6. Electron microscopic studies reveal epithelial cells joined by tight junctions, forming lumina, and displaying long microvilli with length to width ratios often greater than 10. The most important differential diagnostic considerations include florid mesothelial hyperplasia, adenomatoid tumor, carcinoma of the rete testis, and serous papillary tumors. In addition, the various types of testicular germ cell tumors should be considered, including seminomas, embryonal carcinomas, and intratubular germ cell tumors, particularly in tumors with testicular parenchymal involvement. Pleomorphic sarcomas should also be considered, particularly when dealing with the biphasic variant. The prognosis for this entity is grave, with a median survival of 23 months. Aggressive therapy with radical orchiectomy remains the mainstay of treatment.

In plain English

This article was a narrative review, not a new study. The authors summarized published literature on malignant mesothelioma of the tunica vaginalis testis, a tumor arising from the serosal membrane of the tunica vaginalis. The literature they cited puts it at 0.3% to 5% of all mesotheliomas, with approximately 100 cases reported. Citing earlier work, the authors noted that asbestos exposure, trauma, herniorrhaphy and long-standing hydrocele have been implicated, with a relatively stronger correlation for asbestos. One earlier review of 74 cases found asbestos exposure in 34.2%. The article described the tumor's appearance by eye, under the microscope and by electron microscope, and the laboratory stains usually positive, such as calretinin, WT1 and D2-40. It discussed how to distinguish it from mesothelial hyperplasia, adenomatoid tumor, rete testis carcinoma, serous tumors, germ cell tumors and sarcomas. Citing earlier reports, it gave median survival as 23 months (range 2 to 64 months) and radical orchiectomy as the main treatment. The authors concluded that this tumor should be considered for testicular masses, especially in patients exposed to asbestos.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Narrative review of the published literature (diagnostic and differential-diagnosis review), illustrated with pathology images; no original study population
• Who was studied: No study population of its own; the review drew on previously reported cases of malignant mesothelioma of the tunica vaginalis testis (approximately 100 reported since the first in 1957). The source of the illustrative images is not described.
• Exposure: Asbestos exposure (particularly occupational; no fiber type specified), along with trauma, herniorrhaphy, long-standing hydrocele, and potassium bromate in drinking water in animal models, discussed as implicated factors based on earlier literature
• Main results:
  • Citing earlier literature, the tumor represents only 0.3% to 5% of all mesotheliomas
  • Citing an earlier review of 74 cases of mesothelioma of the tunica vaginalis testis, asbestos exposure was found in 34.2%
  • Citing earlier literature, the tumor occurs in middle-aged to elderly men (mean 53.5 years); ultrasonography usually shows hydrocele (56.3%), and some patients present with a paratesticular solid mass (32.8%)
  • The tumor is typically positive for calretinin, WT1, D2-40, epithelial membrane antigen, thrombomodulin and CK7, variably positive for CK5/6, and negative for CEA and CK20
  • On electron microscopy, the tumor cells have long, slender microvilli with a length to diameter ratio typically greater than 10
  • Citing earlier reports, prognosis is generally grave, with median survival of 23 months (range 2 to 64 months); radical orchiectomy is the management, and chemotherapy for metastatic disease has had marginal efficacy
• The authors' conclusion: The authors concluded that diagnosis can be challenging given the tumor's rarity, and that it should be considered in the differential diagnosis of testicular masses, especially if the patient has been exposed to asbestos. Immunohistochemistry and electron microscopy help distinguish it from other tumors.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Tunica Vaginalis, Differential Diagnosis, Testicular Mesothelioma, Parenchyma, Epithelioid, Tubulopapillary, Solid Architectural Pattern.

Related studies

• Mesothelioma of the tunica vaginalis testis: report of 2 cases with asbestos occupational exposure — G. Gorini, M. Pinelli, et al. (2005)
• Mesothelioma of the tunica vaginalis testis — K.J. Butnor, E.N. Pavlisko, et al. (2019)
• Malignant Mesothelioma of the Tunica Vaginalis Testis-A Malignancy Associated With Asbestos Exposure and Trauma: A Case Report and Literature Review — A.A. Baqui, N.A. Boire, et al. (2019)
• Mesothelioma of the tunica vaginalis testis: a rare malignancy mimicking more common inguino-scrotal masses — P.J. Schure, K.C. van Dalen, et al. (2006)
• Pre-operative diagnosis of malignant mesothelioma of tunica vaginalis testis by hydrocele fluid cytology — S.C. Gupta, A.K. Gupta, et al. (1998)
• Well-differentiated papillary mesothelioma of tunica vaginalis testis of unknown malignant potential: Sonographic appearance — K.W.S. Ko, K.S. Tse, et al. (2018)

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