Mesothelioma of the Tunica Vaginalis Testis Initially Treated as Hydrocele: A Case Report

Our plain-English summary of Mesothelioma of the Tunica Vaginalis Testis Initially Treated as Hydrocele: A Case Report, by J.I. Hori, S. Yamaguchi, T. Ohyama, et al (IJU Case Reports, 2026).

The study

• Authors: J.I. Hori, S. Yamaguchi, T. Ohyama, H. Ishida, Y. Takakuwa, M. Sato, A. Homma, S. Matsumoto
• Journal: IJU Case Reports
• Published: 2026;9(5):e70257
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: Herein, we report a case of mesothelioma of the tunica vaginalis testis (MTVT), treated as a hydrocele.

Case Presentation: A 65-year-old man was referred to our hospital after MTVT was incidentally diagnosed during hydrocelectomy performed for recurrent hydrocele. Left hemiscrotectomy was performed, and pathological examination revealed an epithelioid-type MTVT with invasion into the testis and spermatic cord. Immunohistochemistry was positive for D2-40 and calretinin, and negative for cytokeratin 5/6 and carcinoembryonic antigen. The patient remained disease-free for 12 months postoperatively without adjuvant treatment.

Conclusion: MTVT should be considered in patients with long-standing or recurrent hydrocele. Wide surgical excision is essential for local control.

© 2026 The Author(s). IJU Case Reports published by John Wiley & Sons Australia, Ltd on behalf of the Japanese Urological Association.

In plain English

This article is a case report by authors in Japan about one man with mesothelioma of the tunica vaginalis testis (MTVT), a rare cancer of the lining around the testis. The 65-year-old man was referred to the authors' hospital after the cancer was found unexpectedly during surgery for a hydrocele (fluid around the testis) that kept coming back. The authors described him as a patient without asbestos exposure. Surgeons removed the left half of the scrotum (left hemiscrotectomy). Tissue examination showed epithelioid-type mesothelioma that had grown into the testis and spermatic cord. Staining tests were positive for D2-40 and calretinin and negative for cytokeratin 5/6 and carcinoembryonic antigen. The tumor was completely removed, and further chemotherapy was put off. CT scans were planned every 3 months for the first 2 years. The man had no sign of the cancer returning 12 months after surgery. The authors concluded that MTVT should be considered in patients with long-standing or recurrent hydrocele and that wide surgical excision is essential for local control. A single case shows one patient's course, not how often this happens.

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 (one patient)
• Who was studied: One 65-year-old man referred to the authors' hospital (authors based in Asahikawa and Sapporo, Japan) after MTVT was found by chance during surgery for recurrent hydrocele
• Exposure: The authors describe the patient as having no asbestos exposure. The patient had recurrent hydrocele.
• Main results:
  • After left hemiscrotectomy, the pathology showed epithelioid-type MTVT invading the testis and spermatic cord
  • Tumor cells stained positive for D2-40 and calretinin
  • Staining was negative for cytokeratin 5/6 and carcinoembryonic antigen
  • Complete resection was achieved by hemiscrotectomy
  • Adjuvant chemotherapy was deferred
  • Surveillance CT scans were planned every 3 months for the first 2 years, then every 6 months for 5 years
  • The patient remained free of recurrence for 12 months after surgery without adjuvant therapy
• The authors' conclusion: The authors concluded that MTVT should be considered in patients with long-standing or recurrent hydrocele, that wide surgical excision is essential for local control, and that careful postoperative surveillance is needed because the cancer may come back early.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Tunica Vaginalis, Hydrocele, Hydrocelectomy, Hemiscrotectomy, Epithelioid, Spermatic Cord, Immunohistochemistry.

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• Malignant mesothelioma of the tunica vaginalis testis: A rare cause of hydrocele — M. de Sá Barrêto Callou Peixoto, M.K. Bernardo Soares, et al. (2022)
• Malignant Epithelioid Mesothelioma of the Tunica Vaginalis Testis Presenting as Hydrocele in a Kidney Transplant Recipient — B.M. Behers, C.W. Guske, et al. (2024)
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• Metastatic Malignant Mesothelioma of the Tunica Vaginalis Testis Treated With Sequential Immunotherapy, Chemotherapy, and Radiotherapy With Prolonged Disease Stabilisation: A Case Report — N. Mathiyalagan, S. Khan, et al. (2026)

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