分化良好乳突間皮瘤之案例分享

董世祥¹  蔡尚憲^1,2

¹國泰綜合醫院外科部 泌尿科 ²汐止國泰綜合醫院外科部 泌尿科

Well-differentiated papillary mesothelial tumor, a rare para-testicular tumor -- case report

 Shih-Shiang Tung  Shann-Shang Tsai

¹Division of Urology, Department of Surgery, Cathay General Hospital, Taipei City, Taiwan

Division of Urology, Department of Surgery, Sijhih Cathay General Hospital, New Taipei City, Taiwan

Well-differentiated papillary mesothelial tumor is a rare disease in which the diagnosis is hard to make.

A 55-year-old male with diabetes came to our hospital due to left painless scrotal mass noted for 3 weeks. He denied any other clinical symptoms. Testis echo showed an irregular heterogeneous hypervascular neoplasm about 2 cm in size over the upper pole of left testis. Blood tests revealed tumor markers within normal limits. Abdominal CT showed left hydrocele or cystic tumor at left scrotum with prominent left epididymis. Under the impression of left scrotal neoplasm and malignancy cannot be ruled out, he was admitted and received left radical orchiectomy.

During the operation, we found an irregular mass about 2 cm at supra-testicular area and left hydrocele. The tumor confined at the surface of tunica vaginalis with blurred margin to parenchyma of testis. A few small polypoid lesions about 2 mm in diameter were also noted at the inner surface of the hydrocele. The pathology reported both of the main tumor and small papillary lesions were well-differentiated papillary mesothelial tumor arising from tunica vaginalis. The patient discharged 2 days after the operation.

Well-differentiated papillary mesothelial tumor (WDPMT) is a rare benign paratesticular lesion arising from the tunica vaginalis. It is hard to distinguish the benign WDPMT from the malignant mesothelioma. We can only assumption by clinical and histological features. WDPMT is non-complicated in architecture and no stromal invasion. In addition, WDPMT usually associated with hydrocele and has low mitotic activity. All of the above characteristics compatible with our case. However, WDPMT is usually single and the malignant mesothelioma is usually multifocal. Except the major tumor, there were many small papillary lesions scattered over the inner surface of the hydrocele. In conclusion, the features of our case favored the diagnosis of WDPMT but the possibility of malignant mesothelioma cannot exclude completely and we have to closely follow-up in long term.