Benign Mesothelial Proliferations of the Tunica Vaginalis Testis

Our plain-English summary of Benign Mesothelial Proliferations of the Tunica Vaginalis Testis, by C. Manini, E. López-Fernández, N. Cruciano, et al (Clinics and Practice, 2023).

The study

• Authors: C. Manini, E. López-Fernández, N. Cruciano, A. Comandone, J.I. López
• Journal: Clinics and Practice
• Published: 2023;13(5):1130-1136
• Type of article: Case report
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The correct diagnosis of mesothelial proliferations is a classic problem for pathologists, and one which has important clinical implications. A significant number of such cases appear associated with recurrent hydrocele, as an irritative/reactive response to this condition. The morphological spectrum of mesothelial lesions in this topography is broad, and a set of benign conditions may appear, sometimes with florid gross features and cytologic pseudo-atypia. Here, we present two different examples in which malignancy was initially considered in the differential diagnosis.

In plain English

This case report described two men whose surgery for hydrocele (fluid around the testis) found growths of mesothelial cells on the tunica vaginalis, the lining around the testis. In both, malignancy was first considered. The article gave no asbestos exposure history for either man. The first, aged 80, had a giant hydrocele on both sides. Under the microscope, small tube-like structures ran parallel to the surface with no surrounding tissue reaction. Staining showed BAP-1 strongly positive, a very low Ki-67 index, and p53 negative. He was diagnosed with florid benign mesothelial hyperplasia and was free of disease after 8 months. The second, aged 62, had a 1 cm finger-like growth. During surgery it was reported as a papillary mesothelial proliferation of undetermined malignancy. Final review found no atypia or mitoses and a very low Ki-67. He was diagnosed with well-differentiated papillary mesothelioma and was free of disease 2 years later. The authors wrote that such benign lesions have not been associated with asbestos exposure. They concluded that these lesions vary widely in appearance and may pose diagnostic difficulties for general pathologists.

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: case report of two patients, with a discussion of diagnostic features
• Who was studied: Two men with hydrocele: an 80-year-old with obesity, type 2 diabetes and hernias, and a 62-year-old with left scrotal enlargement. No place or dates of treatment are stated.
• Exposure: Not reported. The article gives no asbestos or other occupational exposure history for either patient.
• Main results:
  • Case 1 (80-year-old): the tunica vaginalis showed glandular structures parallel to the wall, with no stromal reaction or wall thickening.
  • Case 1: BAP-1 and CK7 were strongly positive, the Ki-67 index was very low, and p53 was negative.
  • Case 1 was diagnosed as florid benign mesothelial hyperplasia. The patient was free of disease after 8 months of follow-up.
  • Case 2 (62-year-old): during surgery, a 1 cm finger-like (villous) growth was preliminarily reported as a papillary mesothelial proliferation of undetermined malignancy.
  • Case 2: the papillary structures were covered by a single row of flat to cuboidal cells with no atypia or mitoses. BAP-1 was strongly positive and Ki-67 was very low.
  • Case 2 was diagnosed as well-differentiated papillary mesothelioma. The patient was alive and free of disease 2 years after surgery.
• The authors' conclusion: The authors concluded that benign mesothelial proliferations of the tunica vaginalis testis vary widely in appearance, may pose diagnostic difficulties for general pathologists, and usually appear with hydrocele. In the discussion they stated that these lesions have not been associated with asbestos exposure, so distinguishing them from malignant mesothelioma may have medico-legal implications.

Topics

Medical terms in this study, explained in our Lexicon: Tunica Vaginalis, Hydrocele, Differential Diagnosis.

Related studies

• Rare tumors of the testis and mesothelial proliferation in the tunica vaginalis — M. Colecchia, G. Mikuz, et al. (2012)
• Malignant mesothelioma of the tunica vaginalis testis initially misdiagnosed as a benign testicular hydrocele: a case report — C. Zhang, H. Su, et al. (2026)
• Malignant mesothelioma of the tunica vaginalis testis: report of first case with preoperative diagnosis — L. Japko, A.A. Horta, et al. (1982)
• Malignant mesothelioma of the tunica vaginalis testis — K. Antman, S. Cohen, et al. (1984)
• Epidemiology of mesothelioma of the pericardium and tunica vaginalis testis — G. Mezei, E.T. Chang, et al. (2017)
• Malignant mesothelioma of the tunica vaginalis testis: diagnostic studies and differential diagnosis — S.S. Chekol, C.C. Sun (2012)

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