A 69-year-old man presented for surgery for a left hydrocele. Sonography (7.5 MHz) showed a hydrocele and the testicular parenchyma was homogeneous. However, multiple papillary masses in the area of the tunica albuginea and the tunica vaginalis testis were also seen. Testicular serum tumor markers were negative. There was a history of arterial hypertension, coronary artery disease with stenting, type II diabetes mellitus, and obesity. The patient was sexually active, reported no lower urinary tract symptoms, and denied any history of scrotal trauma or exposure to asbestos. Surgery was done by an inguinal incision. Intraoperatively, the testicular sheaths were grossly thickened. A crystalline turf with numerous cystic formations was attached to the tunica vaginalis testis (Fig. 1). After excision, pathology showed a neoplastic change of the tunica vaginalis reported as an epitheloid differentiated mesothelioma (Fig. 2). Staging CT was without pathological findings. After tumor board discussion, adjuvant radiotherapy was given. To date, with 8 years of followup there is no evidence of recurrence. This is a rare case which poses the challenge of diagnosis and treatment as this neoplasia lacks specific clinical and radiological features.

Discussion

Malignant mesothelioma is a rare neoplasia of serous membranes which is often related to prior asbestos exposure. It is derived from pluripotent cells of serous membranes that can differentiate into epithelial or mesenchymal cells and is characterized by diffuse infiltrative growth. The histological picture shows a wide spectrum of different growth forms. Most frequent locations are pleura (70%), peritoneum (28%), and pericardium (1%). In this neoplasia, a variety of genetic defects have been described, but no specific isolated defects (associated chromosomal imbalances: losses on chromosomes 9p, 22q, 4q, 14q, and 1p, and gains on 8q and 1q). Although these tumors are most commonly observed in patients between 55 and 75 years of age, 10% of patients are younger than 25 years.^1,2 Urogenital manifestations are a rarity with only about 100 cases reported.^3–5 Most of these presented with unspecific symptoms such as painless scrotal mass or testicular hydrocele.⁵ Thus, this rare tumor is usually an incidental finding in hydrocele surgery. The pathogenesis is unclear. Due to the small number of cases, there is no agreed uniform treatment. The primary treatment is of course radical surgery (radical orchiectomy). Of the patients who underwent resection of the hydrocele wall only, 35.7% had local recurrence compared to 10.5% after scrotal orchiectomy and 11.5% after inguinal orchiectomy. Clearly, radical orchiectomy is indicated; however, it is unclear whether the scrotal wall should be resected as well. The reported median survival was 23 months, but only 14 months in case of recurrence. The total recurrence rate (local and systemic) was 52.5%. More than 60% of recurrences develop within the first 2 years.^2,6–8 In some cases of disseminated mesothelioma, adjuvant chemotherapy or radiation therapy has been administered. Although reports of adjuvant treatments have been limited, radiotherapy appeared to be more effective than chemotherapy. Thus, the nature of this tumor is highly aggressive, but it can possibly be cured by early and very radical surgery.

Clinical Practice Points

The tumor often presents clinically as a hydrocele, so that it is often an incidental intraoperative finding. Due to the rarity of the disease, the treatment is not clearly defined and after radical surgery interdisciplinary discussion is required.