Benign multicystic mesothelioma arising from the tunica vaginalis

Our plain-English summary of Benign multicystic mesothelioma arising from the tunica vaginalis, by A. Lang, P. Chaudhri (Journal of Surgical Case Reports, 2019).

The study

• Authors: A. Lang, P. Chaudhri
• Journal: Journal of Surgical Case Reports
• Published: 2019;2019(1):rjy361
• Type of article: Case report
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Benign multicystic mesothelioma is an extremely rare neoplasm usually arising from the visceral mesothelium of the peritoneal cavity typically presenting in young to middle-aged women. It has been deemed an indolent tumour with a possible heritable nature, but also a possible reactive neoplasm secondary to trauma. Diagnosis relies on identifying characteristic histology of cysts separated by loose connective tissue stroma and lined by pale, flat or cuboidal mesothelial cells. A 74-year-old male presented with a painless, enlarging scrotal swelling thought to be either an epididymal cyst or hydrocele. He underwent radical orchiectomy and benign multicystic mesothelioma of the tunica vaginalis was characterized on macroscopy and microscopic examination. The potential for malignant transformation of these tumours has not been demonstrated, but they are known to recur. This infrequent presentation of a rare and poorly understood tumour with description of histologic findings may allow for improved diagnosis in other cases.

In plain English

This article was a case report from the histopathology department of Lincoln County Hospital in the UK. It described a 74-year-old man who had had a slowly enlarging, painless swelling on the left side of his scrotum for 20 years. Ultrasound showed a large cystic area measuring 16.6 × 8.2 × 8.8 cm with multiple internal divisions. Radiology at first suspected an epididymal cyst or a hydrocele. He had his left testis surgically removed (left radical orchiectomy). The specimen showed a shrunken (atrophic) testis with a large cluster of fluid-filled cysts attached to it. Under the microscope, the thin-walled cysts were lined by mesothelial cells, and no abnormal-looking cells, dividing cells or dead tissue were seen. Stains were positive for WT-1 and calretinin and negative for desmin, which the authors said fit a diagnosis of benign multicystic mesothelioma. The tumour arose from the tunica vaginalis, the lining around the testis. The article did not mention asbestos or any other exposure history. The authors concluded this was an unusual case that could be treated by surgical removal, and wrote that its description may help with diagnosis in other cases.

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 (single patient)
• Who was studied: one 74-year-old man with a 20-year history of a painless left scrotal swelling, seen in Lincoln, UK; he had a past history of malignant melanoma of the lower back and a carcinoid tumour of the terminal ileum
• Exposure: not reported; the article does not mention asbestos or any other exposure history
• Main results:
  • Ultrasound of the patient's testes showed a large left-sided cystic area of 16.6 × 8.2 × 8.8 cm with multiple septations
  • The patient underwent left radical orchiectomy
  • The specimen showed an atrophic testis of 40 × 30 × 30 mm with a large multiloculated cystic structure attached
  • Microscopy showed no atypia, mitoses or necrotic regions
  • Mesothelial cells were positive for WT-1 and calretinin and negative for desmin, which the authors described as in keeping with benign multicystic mesothelioma
• The authors' conclusion: The authors concluded this was an unusual case of benign multicystic mesothelioma of the tunica vaginalis, presenting as a scrotal swelling in an elderly man, that was amenable to surgical resection. They wrote that describing it may allow improved diagnosis in other cases.

Topics

Medical terms in this study, explained in our Lexicon: Multicystic Mesothelioma (MCM), Tunica Vaginalis, Neoplasm, Mesothelium, Peritoneal Cavity, Histology, Mesothelial Cells, Hydrocele.

Related studies

• Well differentiated (benign) papillary mesothelioma of the tunica vaginalis — R. Chetty (1992)
• Primary Malignant Mesothelioma of the Tunica Vaginalis Presenting as a Benign Scrotal Mass: A Case Report — Z.C. Dagdeviren, O. Amac, et al. (2025)
• Benign Mesothelial Proliferations of the Tunica Vaginalis Testis — C. Manini, E. López-Fernández, et al. (2023)
• Malignant mesothelioma of the tunica vaginalis testis initially misdiagnosed as a benign testicular hydrocele: a case report — C. Zhang, H. Su, et al. (2026)
• Localized benign pleural mesothelioma arising in a radiation field — J.K. Hill, R.F. Heitmiller, et al. (1997)
• Benign Cystic Mesothelioma of the Peritoneum Arising at the Greater Omentum in a 14-Year-Old Boy — Y. Hirayama, N. Higashidate, et al. (2025)

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