Uroradiology & genital male imagingCase Type
Laura Delgado Fernández, Begoña Díaz Barroso, Marta Alhambra Morón, Blanca Muñoz Pedraz, Pedro Álvarez Vallespín, Marta Elena Hernández GarcíaPatient
43 years, male
A 43-year-old male with no medical history was admitted to our hospital referring right testicular pain and enlarging over the past 2 years.
Physical examination showed important hydrocele, being impossible the right testicle palpation.
Scrotal ultrasound images revealed the presence of a homogeneous hypoechoic fluid surrounding the right testis, related to a large hydrocele. In addition, arising from the right tunica vaginalis, multiple isoechoic surface polypoid nodules of different sizes (the biggest of 7 mm) were observed.
Testis and epididymis had no relevant findings. No calcifications were identified.
These findings are suggestive of scrotal mesothelioma.
Mesothelioma is an uncommon malignant tumor that arises from mesenchymal tissue and involves pleura, peritoneum, pericardium and very rarely, the tunica vaginalis (< 5%). [1,2,3]
The tunica vaginalis is a layer of reflected peritoneum which covers the testis (except the posterior border). 
Malignant mesothelioma of the tunica vaginalis mostly affects men older than 45 years old. The main risk factor which predisposes to mesothelioma is asbestos exposure. Furthermore, mesothelioma is associated with long-term hydrocele and recurrent epididymitis (chronic inflammation). [1,2]
Regarding the histologic features, there are three subtypes of mesothelioma: epithelioid (the most common in the tunica vaginalis and peritoneal cavity), sarcomatoid or mesenchymal (pleural type) and biphasic (affects to the serosa membrane). [1,2,3]
Malignant mesothelioma is an infiltrative and aggressive tumour and at the diagnosis it has local invasion (subtunical tissue and testis) on half of the patients. 
It is a challenging diagnose because there are no specific clinical features of malignant mesothelioma. It should be suspected in patients with a history of enlarging and recurrent hydrocele and, sometimes, with a painless mass. Moreover, mesothelioma should be taken into account in patients with scrotal pathology and asbestos exposure. [3,4]
Ultrasound describes mesothelioma as a large hydrocele with multiple papillary isoechoic excrescences arising from the tunica vaginalis cavity and of different sizes. Generally, testicles and epididymis are normal. Color Doppler is useful to rule out differential diagnosis, although sometimes it can show hyperemia of the tunica vaginalis. [2,3,4]
The majority of cases are diagnosed during or after the surgery, due to histological findings and immunohistochemical staining, which has an important role in an accurate diagnosis (calretinin and cytokeratin are some of the markers investigated). 
Computed tomography (CT) is necessary to stage the tumour and diagnose distant metastases (being aware of retroperitoneal adenopathies). PET-CT is performed to diagnose distant metastases. 
Due to its malignancy, mesothelioma´s treatment is based on radical inguinal orchiectomy with or without inguinal and retroperitoneal lymphadenectomy. Adjuvant radiotherapy and chemotherapy (cisplatin and permetrexed) are controversial. [2,3]
Malignant mesothelioma has a poor prognosis, with a mortality of 53% over a mean follow-up period of 2 years. 
Malignant mesothelioma should be taken into account in the differential diagnosis of hydrocele, moreover, in patients with a history of scrotal pathology and asbestos exposure. 
Imaging findings are useful for the diagnosis, but the final diagnosis is confirmed with histological examination. Surgery is crucial in the treatment. [2,4]
 Jing-Liang Chen and Yung-Hsiang Hsu. 2009 Malignant mesothelioma of the tunica vaginalis testis: A Case report and literature review. Kaohsiung J Med Sci February 2009 • Vol 25 • No 2 77. Elsevier.
 Chirag B. Punatar et al. 2013. Malignant mesothelioma of tunica vaginalis without any risk factors: An uncommon case. Hinyokika Kiyo. 2013 Sep;59(9):603-6.
 Neng Zhang et al. 2017. Malignant mesothelioma of the tunica vaginalis testis: A case report and literature review. MOLECULAR AND CLINICAL ONCOLOGY 7: 1053-1056, 2017.
 Victoria Garriga et al. 2009. US of the Tunica Vaginalis Testis: Anatomic Relationships and Pathologic Conditions. RadioGraphics 2009; 29:2017–2032.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.