[Paratesticular Fibrous Pseudotumor Difficult to Differentiate from Testicular Tumor --Case Report-].

A 74-year-old male patient presented with painless enlargement of the right scrotum that had persisted for three months. His past medical history included a gastrojejunostomy for metastatic gastric cancer and laparoscopic right inguinal hernia repair. Tumor markers were negative. However, an ultrasound examination revealed a mosaic-patterned mass measuring 4 cm in diameter within the scrotum, while an enhanced mass within the right scrotum was shown by contrast-enhanced computed tomography, raising suspicion of a malignant tumor. Consequently, a right high orchiectomy procedure was performed. Following surgery, histopathological examination results showed nodules composed of proliferating fibroblasts and collagen fibers surrounding the affected testis, which included bundles of smooth muscle and bony fragments within. Mild chronic inflammatory cell infiltration, including lymphocytes, plasma cells, and eosinophils, was also noted extending from the perivascular region to the stroma. As a result, a diagnosis of paratesticular fibrous pseudotumor was determined. Findings obtained in the present case revealed a rare condition and indicate that paratesticular fibrous pseudotumor should be considered as a differential diagnosis when a testicular tumor condition is suspected.