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Introduction The tunica vaginalis testis is a pouch of serous membrane covering the testis and derived from the peritoneum. Serous membranes are any of various thin membranes (as the peritoneum, pericardium, or pleurae) that consist of a single layer of thin flat mesothelial cells resting on connective-tissue, secrete a serous fluid, and usually line bodily cavities or enclose the organs contained in such cavities. Like the tissue that lines or surrounds the lung or the tissue that surrounds the stomach and other organs, the tunica vaginalis surrounds the testis. A cancer of this type of tissue is called a mesothelioma. The most common mesothelioma is of the lung called pleural mesothelioma. The next most common is peritoneal mesothelioma. Pericardial (tissue surrounding and enclosing the heart) mesothelioma and tunica vaginalis testis mesotheliomas are quite rare. Fewer than 100 cases of gonadal mesothelioma have been reported in the medical literature. One article states 64 previous cases. Most patients are in their 50s or older, but about ten percent of the patients are younger than 25 years. Asbestos exposure is documented in approximately one-half of the more recently reported cases. Patients generally present with a hydrocele (an accumulation of serous fluid in a sac-like cavity (as the scrotum) or hernia. Serous fluid resembles serum and has a thin watery constitution. An accurate preoperative diagnosis has been reported in only two cases. This means that the pre-operative diagnosis of this very rare cancer is usually not suspected and is only made after surgery to remove the testicle. Cellular Classification These tumors appear highly aggressive with early onset of metastasis (spread of the cancer). Histologically (the study of cells and tissue on the microscopic level), the tumors may be epithelial, fibrous, or biphasic, just like other mesotheliomas. Histologically, these tumors are composed of fibrous or epithelial elements or both. The epithelial form occasionally causes confusion with peripheral anaplastic lung carcinomas or metastatic carcinomas (cancers that have spread from somewhere else and therefore not mesothelioma). Attempts at diagnosis by cytology or needle biopsy of the pleura are often unsuccessful. It can be especially difficult to differentiate mesothelioma from adenocarcinoma on small tissue specimens. Thoracoscopy (examination of the chest and especially the pleural cavity by means of a thoracoscope) can be valuable in obtaining adequate tissue specimens for diagnostic purposes. Examination of the gross tumor (large enough to see by eye without a microscope) at surgery and, one back in the pathology lab, the use of special stains or electron microscopy can often help. The special stains reported to be most useful include periodic acid-Schiff diastase, hyaluronic acid, mucicarmine, CEA, and Leu M1. Histologic appearance (at a cellular level seen only with a microscope) seems to be of prognostic value, and most clinical studies show that patients with epithelial mesotheliomas have a better prognosis than those with sarcomatous or mixed histology mesotheliomas. In contrast to the benign (non-cancerous) variants of mesotheliomas, these tumors often show significant nuclear atypia (the nucleus doesn’t look normal), mitotic activity (how rapidly the cells appear to be dividing), and invasion of the epididymis, spermatic cord, lymphatic spaces, or the fibrous tissue of the tunica. See an anatomy book or the website http://training.seer.cancer.gov/module_anatomy/anatomy_physiology_home.html for detail on what and where these different structures are. Diagnosis and Treatment All patients with a suspected testicular malignancy should undergo a radical or high inguinal orchiectomy (surgical excision of a testis or of both testes - called also orchidectomy). This means that the tumor should not be removed directly through an incision in the scrotum, which may seem like the easiest and most direct route to the affected testicle. Rather, the entire testicle and associated tissue should be removed through an incision in the lower abdomen. Local resection of the tumor or hydrocelectomy (removal of the hydrocele) is associated with a high recurrence rate compared with high inguinal orchiectomy. Because preoperative diagnosis of gonadal mesothelioma is very difficult, management should be as for any testicular tumor. The inguinal approach (access through the lower abdomen) avoids interruption of the scrotal lymphatics, which would alter the metastatic (the spread of cancer) pathway of the tumor, and also allows complete removal of the spermatic cord up to the internal ring. This approach, as in regular testicular cancer, avoids spreading the cancer. Patients with evidence of disease extending into the retroperitoneal lymph nodes should undergo a retroperitoneal lymphadenectomy (removal of the swollen or abnormal looking lymph nodes from the retroperitoneal area). The retroperitoneum is the space behind the peritoneum. There are little data regarding the use of adjuvant therapy after resection of gonadal mesothelioma. Adjuvant therapy means treatment that is given in addition to the main treatment, surgery. Typical adjuvant therapies in cancer are chemotherapy and radiation therapy. Because of the rarity of this cancer it is unknown whether adding treatments beyond surgery is of any value. Prognosis The overall recurrence rate (local and disseminated) for gonadal mesothelioma can be as high as 52%, with 38% of patients dying of disease progression. Local recurrence occurs in 36% of patients who undergo local resection of the hydrocele wall; 10% after scrotal orchiectomy and 12% after inguinal orchiectomy. More than 60% of recurrences developed within the first two years of the follow-up. The median survival of the patients averaged 23 months. Median survival means half the patients lived more than that time and half lived less than that time. Additional Information on malignant mesothelioma of the tunica vaginalis testi. The following is an article from the British Journal of Radiology (2004) 77, 780-781. It has been modified for patient understanding. While it is somewhat difficult to read, you can work through it with a medical dictionary. © 2004 British Institute of Radiology -------------------------------------------------------------------------------- Case report Malignant mesothelioma of the tunica vaginalis testis Malignant mesothelioma of the tunica vaginalis is a rare primary tumor that occurs in a broad age range, with the highest incidence between 55 years and 75 years. Although trauma, herniorrhaphy and long-term hydrocele have been considered as the predisposing factors for development of malignant mesothelioma, the only well established risk factor is asbestos exposure. A hydrocele is an accumulation of serous fluid in a sac-like cavity adjacent the testicle; a swelling due to the accumulation of serous fluid in the tunica vaginalis of the testis or in the spermatic cord. The ultrasound features of mesothelioma of the tunica vaginalis testis have not been widely reported. Hydrocele, either simple or complex is present and may be associated with: (1) well organized soft tissue fronds of mixed echogenicity (a hypoechoic centre surrounded by a hyperechoic rim) which extends into the hydrocele; (2) multiple extratesticular nodular masses of increased echogenicity arising from the scrotal wall; and (3) focal thickening of the tunica vaginalis testis with presence of nodularity. The present case differs from the usual presentation; the mesothelioma demonstrated in our case consisted of a well-defined, slightly lobulated mass occupying the left epididymal head mimicking an epididymal tumor, and differentiation from the most common epididymal tumor, adenomatoid tumor was difficult. Adenomatoid tumor, also known as benign mesothelioma, occurs in a younger age group, usually in the 3rd to 4th decades. The ultrasound features of an adenomatoid tumor may be variable and usually consists of a well-defined round shaped nodule having variable echogenicity ranging from hypoechoic to hyperechoic. The adenomatoid tumor is mostly located in the epididymal tail. As this is a benign tumor, surgical excision is unnecessary unless it is large enough to cause discomfort to the patient. However for patients with mesothelioma, surgical intervention is necessary as this is an aggressive tumor. 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. However fluid cytological analysis is frequently negative. Some experts suggest direct ultrasound guided fine needle aspiration of the solid masses rather than fluid from the hydrocele, however this is still subject to sampling error. Unlike the more common adenomatoid tumor, which is usually well defined and round in shape, the present case demonstrated an oval and slightly lobulated mass. Surgery was therefore performed, due to the uncertainty of the diagnosis. Color Doppler ultrasound features of mesothelioma may show decreased vascularity in the tumor compared with normal testicular parenchyma, consistent with the present case which also revealed relative hypovascularity of the tumor. Even though ultrasound may not be able to differentiate a malignant paratesticular (around the testes) tumor from the more common benign tumor the role of ultrasound cannot be ignored in clinical practice. Besides determining whether a lesion is cystic (a fluid filled sac which is usually not cancer) or solid (which may be cancer) it is also helpful in differentiating whether the lesion is a neoplasm or infectious process, hence avoiding unnecessary surgical intervention. The low cost of ultrasound, absence of ionizing radiation, convenience and ready availability, renders ultrasound the imaging modality of choice in the evaluation of intrascrotal, extratesticular mass compared with the other imaging modalities such as CT or MRI. In conclusion, malignant mesothelioma of the tunica vaginalis is a rare neoplasm, whenever a paratesticular mass is seen in the epididymis, the possibility of mesothelioma should be included in the differential diagnosis even when there is no history of asbestos exposure such as in the present case. As these tumors may mimic adenomatoid tumors, fine needle aspiration of the tumor may be contributory in making a pre-operative diagnosis in these patients. This is important as it affects the surgical approach and the patient's prognosis. However, when a lobulated mass rather than a round shape is encountered, surgical intervention is recommended. Useful medical journal article references for malignant mesothelioma of the tunica vaginalis testis Search PubMed http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed to look at the articles listed below. Most will have an abstract; a brief description of the article. Some will have a link to the full text of the article. You can also see the full text at a medical library assuming they have the particular journal you are looking for. 1: Nakano T. Related Articles, Links 2: Hammar SP. Related Articles, Links 3: Hassan R, Alexander R. Related Articles, Links 4: Sterman DH, Albelda SM. Related Articles, Links 5: Churg A. Related Articles, Links 6: Garcia de Jalon A, Gil P, Azua-Romeo J, Borque A, Sancho C, Rioja LA. Related Articles, Links 7: Gupta NP, Kumar R. Related Articles, Links 8: Loggie BW. Related Articles, Links 9: Kanazawa S, Nagae T, Fujiwara T, Fujiki R, Mukai N, Sugihara Y, Yamaguchi N, Ohtani H, Higami Y, Ikeda T, Tsunoda T. Related Articles, Links 10: Lalowicz I. Related Articles, Links 11: Gupta NP, Agrawal AK, Sood S, Hemal AK, Nair M. Related Articles, Links 12: Plas E, Riedl CR, Pfluger H. Related Articles, Links 13: Melhouf MM, Elghazi el-A, Errihani H, Sifat H, Hadadi K, Kanouni L, Mansouri H, Alhilal M, Mansouri A, Benjaafar N, Elgueddari B el-K. Related Articles, Links 14: Wakasugi E, Ishii T, Akiyama T, Kurita T, Kadowaki T, Uemura T. Related Articles, Links 15: Berti E, Schiaffino E, Minervini MS, Longo G, Schmid C. Related Articles, Links 16: Machida T, Yamada T, Kobayashi N, Takeuchi S, Saito H, Itoyama S. Related Articles, Links 17: Menut P, Herve JM, Barbagelata M, Botto H. Related Articles, Links 18: Ahmed M, Chari R, Mufi GR, Azzopardi A. Related Articles, Links 19: Jones MA, Young RH, Scully RE. Related Articles, Links 20: Eden CG, Bettochi C, Coker CB, Yates-Bell AJ, Pryor JP. Related Articles, Links 21: Biermann CW, Moch H, Gasser TC, de Riese W, Rutishauser G. Related Articles, Links 22: Borrell Palanca A, Alapont Perez M, Compan Quilis A, Gil Salom M, Gunthner S, Chuan Nuez P, Santamaria Meseguer J, Rafie Mazketly W, Garcia Garzon J, Soler Martinez J, et al. Related Articles, Links 23: Moch H, Ohnacker H, Epper R, Gudat F, Mihatsch MJ. Related Articles, Links 24: Suyama I, Masui N, Kanzaki M, Moriuchi A, Uchida T, Mashimo S. Related Articles, Links 25: Fujii Y, Masuda M, Hirokawa M, Matsushita K, Asakura S. Related Articles, Links 26: Kuwabara H, Uda H, Sakamoto H, Sato A. Related Articles, Links 27: Mirabella F. Related Articles, Links 28: Carp NZ, Petersen RO, Kusiak JF, Greenberg RE. Related Articles, Links 29: Kamiya M, Eimoto T. Related Articles, Links 30: Grove A, Jensen ML, Donna A. Related Articles, Links 31: Velasco AL, Ophoven J, Priest JR, Brennom WS. Related Articles, Links 32: Mitsumori K, Elwell MR. Related Articles, Links 33. Plas E, Riedl CR, Pfluger H. Malignant mesothelioma of the tunica vaginalis: review of the literature and assessment of prognostic parameters. Cancer 1998;83:2437–46. 34. 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;32:687–9. 35. 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;19:815–25. 36. Fields JM, Russell SA, Andrew SM. Ultrasound appearances of a malignant mesothelioma of the tunica vaginalis testis. Clin Radiol 1992;46:128–30. 37. Bruno C, Minniti S, Procacci C. Diagnosis of malignant mesothelioma of the tunica vaginalis testis by ultrasound-guided fine-needle aspiration. J Clin Ultrasound 2002;30:181–3. 38. Wolanske K, Nino-Murcia M. Malignant mesothelioma of the tunica vaginalis testis: atypical sonographic appearance. J Ultrasound Med 2001;20:69–72.[Free Full Text]
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