Malignant mesothelioma of the tunica vaginalis testis: A case report

The aim of the present study was to report a case of malignant mesothelioma of the tunica vaginalis testis (MMTVT) and to discuss clinicopathological features and therapeutic dilemmas to provide references for individualized management of similar cases. The case of a 57-year-old male patient with MMTVT, admitted in February 2025, was retrospectively analyzed. The patient presented with left scrotal pain and had a 30-year history of vasectomy. Scrotal ultrasound, testicular MRI and serum tumor marker analyses were performed, followed by local resection of the left tunica vaginalis tumor under spinal anesthesia. Diagnosis was confirmed using postoperative pathology and immunohistochemistry. After comprehensive counseling on recurrence and metastasis risks, the patient and their family declined radical orchiectomy and adjuvant chemotherapy, and close surveillance was instituted. Postoperative pathology confirmed biphasic MMTVT. Immunohistochemistry demonstrated positive mesothelial biomarkers: D2-40(+), calretinin (focal+) and cytokeratin 5/6 (focal weak+). Ki-67 was ~10%, with wild-type p53 expression. The tumor was completely excised with negative margins. No recurrence or metastasis was observed at the 12-month follow-up. This case, presenting with scrotal pain as initial presentation, further highlights the clinical heterogeneity of MMTVT. The remote vasectomy history, which is rarely documented, raises an etiological question for investigation. The biphasic subtype with low Ki-67 suggests that prognostic evaluation requires integrating histological subtype and molecular biomarkers. The 12-month recurrence-free survival time following isolated local excision provides preliminary evidence for organ-sparing management, although long-term outcomes require continued surveillance.