228 hydrocele in over 55% of cases or a paratesticular mass in over 30% [4]. Bisceglia et al showed that a hydrocele was positive in 26 out of 60 cases, a scrotal mass in 22 cases, and both symptoms in 3 cases [6]. In contrast, primary tumors arising from the spermatic cord [5] were very rare. Tumors arising from the peritoneal mesothelium of an inguinal hernia sac, which are included among paratesticular MMs, account for less than 10% of total cases [6]. 　A history of direct occupational or familial asbestos ex- posure is found in around 35% to 40% of cases [4]. Those diagnosed between the ages of 20 and 40 years usually have a history of childhood exposure. The long latency period be- tween exposure to asbestos and the onset of MM, which can range from 15 to 60 years, explains why mortality rates from mesothelioma have continued to rise. The diagnosis of mesothelioma is directly attributable to occupational as- bestos exposure; however, there is evidence that meso- thelioma may result from both para-occupational ex- posure, such as women having laundered their husband's overalls, and environmental exposure [7]. 　The combination of an accurate history, examination, ra- diology, and the acquisition of pathology is essential in the diagnosis of mesothelioma. On clinical examination, the tumor is mostly misinterpreted as a testicular tumor or hy- drocele, but other preoperative diagnoses include diverse entities such as epididymitis, scrotal or inguinal hernia, spermatocele, and adenomatoid tumor [4,5]. Hence, cor- rect preoperative diagnoses are made only in very few cases. 　Radiological imaging is essential for the diagnosis, stag- ing, and management of mesothelioma. X-ray, CT, mag- netic resonance imaging (MRI), and positron emission to- mography (PET) have all been used to evaluate the disease [7]. 　The correct diagnosis is usually determined on post- operative pathologic examination. Microscopically, a para- testicular MM is most often a pure epithelial type or mixed; only 2 cases of a pure sarcomatous spindle cell type have been reported [6]. The architectural pattern is usually pap- illary or tubulo-papillary. Radical orchiectomy with com- plete histologic examination to exclude any foci of stromal invasion is mandatory for accurate diagnosis, and a close follow-up of the patient is required for an adequate duration. Immunohistochemically, mesotheliomas are positive for cytokeratin, cytokeratin 7, epithelial mem- brane antigen, thrombomodulin, and calretinin, whereas they are negative for cytokeratin 20. Carcinoembryonic an- tigen and Leu-M1 may sometimes give an inappropriate hyaluronidase-sensitive staining. Vimentin may provide variable outcomes, ranging from negative to focally or dif- fusely positive results. 　The differential diagnosis of paratesticular mesothelio- ma mostly includes both benign neoplastic and nonneo- plastic mesothelial lesions arising in this site, such as ad- enomatoid tumors, cysts of the tunica albuginea, cysts of the testicular parenchyma, hydrocele-associated reactive mesothelial hyperplasia, and nonmesothelial tumors of di- Korean J Urol 2011;52:225-229 Park et al verse histogenetic origin [6]. 　Mesotheliomas are difficult to manage, and no clear guidelines exist for management. First-line surgical treat- ment is inguinal radical orchiectomy. 　Paratesticular MMs are aggressive neoplasms capable of widespread local involvement as well as lymphatic and hematogeneous metastases [4,8,9]. Recurrence occurs in 60% of patients within 2 years, with a mortality rate of 30% after a median survival of 24 months [4,8]. Surgical options in the inguino-scrotal area as well as an early tumor stage at the time of diagnosis are likely to result in a slightly bet- ter prognosis. The most important prognostic factor for sur- vival is the age of patient at the time of diagnosis, with sig- nificantly better survival in patients younger than 60 years of age [4,8,10]. 　A more limited conservative approach should be dis- couraged because it is almost always complicated by local recurrences. CT study is recommended for detection of ret- roperitoneal lymph nodal spread, which is found in 15% of cases [8]. Para-aortic lymph nodes are the most frequently and primarily involved, whereas pelvic (iliac and ob- turator) nodes are usually involved in more advanced stages. Radiation therapy and chemotherapy have been used [10], but showed minimal effectiveness. Early accu- rate, preoperative diagnosis remains the sole favorable fac- tor for more effective treatment and control of this disease. 　Despite their rare occurrence in the spermatic cord, par- atesticular mesothelioma needs to be suspected, especially in patients with a history of asbestos exposure. In addition, after the diagnosis is confirmed as MM, a more aggressive management including a second-look operation with pelvic lymphadenectomy or adjunctive chemotherapy may be required. Conflicts of Interest The authors have nothing to disclose. REFERENCES 1. Park HM, Kim JH, Bae SG, Kwon TK, Chung SK. A case of malig- nant mesothelioma of tunica vaginalis. Korean J Urol 1997;38: 1132-4. 2. Lee SC, Lee JK. A case of primary malignant mesothelioma of tun- ica vaginalis testis. Korean J Urol 1991;32:843-5. 3. Shin TK, Lee TY, Park MH. Mesothelioma of the tunica vaginalis of the spermatic cord with coincidental finding renal cell carci- noma. Korean J Urol 1995;36:1142-6. 4. Plas E, Riedl CR, Pflüger H. Malignant mesothelioma of the tun- ica vaginalis testis: review of the literature and assessment of prognostic parameters. Cancer 1998;83:2437-46. 5. Perez-Ordonez B, Srigley JR. Mesothelial lesions of the para- testicular region. Semin Diagn Pathol 2000;17:294-306. 6. Bisceglia M, Dor DB, Carosi I, Vairo M, Pasquinelli G. Parates- ticular mesothelioma. Report of a case with comprehensive re- view of literature. Adv Anat Pathol 2010;17:53-70. 7. Moore AJ, Parker RJ, Wiggins J. Malignant mesothelioma. Orphanet J Rare Dis 2008;3:34. 8. García de Jalón A, Gil P, Azúa-Romeo J, Borque A, Sancho C, Rioja