Primary Malignant Mesothelioma of the Tunica Vaginalis Presenting as a Benign Scrotal Mass: A Case Report

Our plain-English summary of Primary Malignant Mesothelioma of the Tunica Vaginalis Presenting as a Benign Scrotal Mass: A Case Report, by Z.C. Dagdeviren, O. Amac, Y. Dere, et al (Curēus, 2025).

The study

• Authors: Z.C. Dagdeviren, O. Amac, Y. Dere, E. Derekoylu
• Journal: Curēus
• Published: 2025;17(8):e90608
• Type of article: Case report
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Primary malignant mesothelioma of the tunica vaginalis is an exceptionally uncommon neoplasm, comprising a very small fraction of all mesothelioma cases. Due to its nonspecific clinical presentation, it is frequently misdiagnosed as benign scrotal conditions, such as a hydrocele. In our case, a 77-year-old male presented with a gradually enlarging swelling in the left hemiscrotum. Scrotal Doppler ultrasonography (USG) and magnetic resonance imaging (MRI) revealed a hydrocele with polypoid masses and nodular soft tissue components of the tunica vaginalis. Tumor markers were normal. Surgical exploration revealed multiple solid masses on the testis and spermatic cord. Histopathologic examination confirmed malignant mesothelioma of epithelioid type, supported by immunohistochemical reactivity for calretinin, cytokeratin 7 (CK7), cytokeratin 5/6 (CK5/6), pan-cytokeratin (PanCK), Wilms tumor 1 (WT1), and loss of BRCA1-associated protein-1 (BAP1). Following the diagnosis of primary tunica vaginalis mesothelioma, the patient underwent radical inguinal orchiectomy and hemiscrotectomy. Adjuvant chemotherapy with pemetrexed and cisplatin was administered. No recurrence was detected after seven cycles, and the patient remains disease-free. This case highlights the diagnostic challenges of tunica vaginalis mesothelioma because of its infrequency and clinical similarity with benign processes. Diagnosis needs to be based on multimodal imaging, histopathology, and immunohistochemistry. Early and total surgical intervention followed by adjuvant therapy may hold the key to successful treatment.

Copyright © 2025, Dagdeviren et al.

In plain English

This case report described one man, aged 77, seen at a urology clinic in Mugla, Turkey, in July 2024 with left scrotal swelling that had grown over six months. He was retired from a desk job and had no history of asbestos exposure. Ultrasound and MRI showed fluid around the testis (a hydrocele) with nodular soft tissue, and blood tumor markers were normal. Surgery in October 2024 found multiple solid lesions of 1-2 cm on the testis and spermatic cord. Microscopic and staining tests, including loss of a protein called BAP1, led to a diagnosis of epithelioid malignant mesothelioma. Scans found no other tumor site, so it was considered primary mesothelioma of the tunica vaginalis, the lining around the testis. In December 2024 the left testis and half of the scrotum were removed, and no remaining tumor was found in the testis or epididymis. After seven cycles of cisplatin and pemetrexed chemotherapy, scans showed no recurrence and he remained disease-free. The authors concluded that this rare tumor may be mistaken for benign conditions such as hydrocele.

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 77-year-old man seen at the authors' urology clinic (Mugla Sitki Kocman University, Turkey) in July 2024 with left scrotal swelling that had increased gradually over six months
• Exposure: No asbestos exposure was reported. The patient was retired from a desk job and had no history of asbestos exposure.
• Main results:
  • MRI showed a 12-cm cystic area with nodular soft tissue at the level of the left testis. Ultrasound showed hydrocele on both sides, mainly on the left.
  • The patient's tumor markers (beta-hCG, AFP and LDH) were within normal limits.
  • Surgical exploration in October 2024 found multiple solid suspicious lesions 1-2 cm in diameter on the testis and spermatic cord.
  • The tumor was diagnosed as mesothelioma of the epithelioid subtype, based on microscopic appearance and immunohistochemical staining, including loss of BAP1 nuclear staining.
  • Postoperative scans found no other tumor site or metastasis, so the case was considered primary tunica vaginalis mesothelioma.
  • After left radical inguinal orchiectomy and hemiscrotectomy in December 2024, no residual lesions were found in the testicular parenchyma or epididymis.
  • After seven cycles of adjuvant chemotherapy with cisplatin and pemetrexed, CT scans showed no residue or recurrence, and the patient remained disease-free.
• The authors' conclusion: The authors concluded that malignant tunica vaginalis mesothelioma is a rare tumor that may be misdiagnosed as benign scrotal conditions such as hydrocele. They said the case highlights keeping mesothelioma in mind for unusual scrotal swellings and considering early active treatment.

Topics

Medical terms in this study, explained in our Lexicon: Mesothelioma, Tunica Vaginalis, Neoplasm, Hydrocele, Tumor Marker, Spermatic Cord, Epithelioid, Calretinin.

Related studies

• Malignant mesothelioma of the tunica vaginalis: presenting with intermittent scrotal pain and hydrocele — T. Esen, O. Acar, et al. (2012)
• Primary malignant mesothelioma of the tunica vaginalis presenting as hydrocele: imaging pitfalls — J. Naidu, N.G. Joseph, et al. (2026)
• 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)
• Malignant mesothelioma of the tunica vaginalis: a atypical presentation of a rare scrotal tumour — M.C. Harris, C. Logan, et al. (2019)
• Multicystic benign cystic mesothelioma presenting as a pelvic mass — M. Momeni, E. Pereira, et al. (2014)
• Benign multicystic peritoneal mesothelioma presenting as a ghost abdominal mass — H. Jerraya, W. Ghariani, et al. (2016)

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