Malignant mesothelioma of the epididymis is a very rare tumor. We report a case of a 33-year old male with a left hydrocele that presented for evaluation of infertility. Scrotal ultrasound revealed a left extratesticular mass. Final pathology revealed malignant mesothelioma involving the epididymis, with well differentiated epithelioid morphology. Metastatic workup was negative.

A 33-year-old male with a left hydrocele presented with the complaint of infertility. Scrotal ultrasound revealed a 1.5 cm extratesticular mass on the left epididymis. Due to his desire to have children, he elected to delay surgical removal of the mass.

Over the course of 42 months, the patient had 6 surveillance scrotal ultrasounds. The epididymal mass enlarged to 2.2 cm and 2 additional masses, each 0.8 cm in size, appeared on the left scrotal wall. The patient and his wife were able to have both a daughter and a son during this time.

The patient underwent a bilateral vasectomy, left hydrocelectomy and left epididymectomy. Final pathology revealed malignant mesothelioma, predominantly showing well differentiated epitheloid morphology, involving the epididymis. In addition, two foci of malignant mesothelioma, predominantly showing well differentiated epitheloid morphology, involving the hydrocele sac was also seen.

The patient denied any history of asbestos exposure. Evaluation with a chest X-ray and CT scan of the abdomen and pelvis was negative. The patient then underwent a left radical orchiectomy approximately one month after his previous surgery. Final pathology was negative for residual mesothelioma. Repeat CT scan of the chest, abdomen and pelvis, performed at four months post-operatively, was also negative. The patient continues to follow-up regularly and is disease-free at 9 months.

Paratesticular mesotheliomas are rare tumors, with less than 250 cases reported to date, and account for only 0.3 to 1.4% of all cases of malignant mesotheliomas [1]. It can occur at any age with the highest incidence between 55 years and 75 years [2]. Although trauma, herniorrhaphy and long-term hydrocele [3] have been considered as the predisposing factors for development of malignant mesothelioma, the only well established risk factor is asbestos exposure [2,4]. However, a correlation between asbestos exposure and mesothelial neoplastic proliferation could be documented in only less than half of the cases [2]. Out patient denied having any previous exposure to asbestos.

Patients with malignant mesothelioma of the tunica vaginalis frequently have a progressively enlarging hydrocele, and rapid re-accumulation of fluid after aspiration raises the suggestion of malignancy [5]. The diagnosis can sometimes be made only after presentation with a recurrent hydrocele or invasion of the scrotum [6]. In our case, the initial epididymal tumor increased in size at a very slow rate but eventually subsequent small tumors arose from the hydrocele sac.

Sonographically, malignant mesothelioma is usually characterized by a hypoechoic hydrocele with heterogeneous masses of increased echogenicity at the periphery [7]. However, ultrasonography is not able to definitively determine the actual disease process. As in our case, the radiology reports suggested the possibility of a benign epididymal mass, supernumerary testis or epididymal neoplasm- either primary or metastatic.

Radical inguinal orchiectomy is accepted as the optimal treatment for paratesticular malignant mesothelioma [2]. The necessity for inguinal or iliac lymph node dissection as primary therapy remains controversial [2]. The role of chemotherapy for malignant mesothelioma remains undefined [8]. Additionally, the efficacy of adjuvant radiotherapy has not yet been clearly determined [2].

Local recurrence after orchiectomy is reported in approximately 10% of the patients [2]. Almost 40% of the patients die from their disease, with a median survival of 24 months [2,4]. Computed tomography scans are recommended for detection of retroperitoneal lymph nodal spread, which is found in 15% of cases [9] and for which retroperitoneal lymphadenectomy may be considered [4,9].

Bisceglia M, Dor DB, Carosi I, Vairo M, Pasquinelli G: Paratesticular mesothelioma. Report of a case with comprehensive review of literature. Adv Anat Pathol 2010;17:53-70.
Plas E, Riedl CR, Pfluger H: Malignant mesothelioma of the tunica vaginalis: review of the literature and assessment of prognostic parameters. Cancer 1998;83:2437-2446.
Gurdal M, Erol A: Malignant mesothelioma of tunica vaginalis testis associated with long term hydrocele: could hydrocele be an etiological factor? Int Urol Nephrol 2001;32:687-689.
Jones MA, Young RH, Scully RE: Malignant mesothelioma of the tunica vaginalis: a clinoco-pathologic analysis of 11 cases with review of the literature. Am J Surg Pathol 1995;19:815-825.
Wolanske K, Nino-Murcia M: Malignant mesothelioma of the tunica vaginalis testis: atypical sonographic appearance. J Ultrasound Med 2001;20:69-72.
Reynard JM, Hasan N, Baithun SI, Newman L, Lord MG: Malignant mesothelioma of the tunica vaginalis testis. Br J Urol 1994;74:389-390.
Fields JM, Russell SA, Andrew SM: Case report: ultrasound appearances of a malignant mesothelioma of the tunica vaginalis testis. Clin Radiol 1992;46:128-130.
Antman K, Cohen S, Dimitrov NV, Green M, Muggia F: Malignant mesothelioma of the tunica vaginalis testis. J Clin Oncol 1984;2:447-451.
Garcia de Jalon A, Gil P, Azua-Romeo J, Borque A, Sancho C, Rioja LA: Malignant mesothelioma of the tunica vaginalis. Report of a case without risk factors and review of the literature. Int Urol Nephrol 2003;35:59-62.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.