Paratesticular tumor-like lesions.

The diverse non-neoplastic lesions that occur in the paratesticular region and may potentially mimic neoplasms are considered. These include some aspects of normal histology such as a cribriform pattern of the epididymis, bizarre nuclear atypia within epididymal epithelial cells and the presence of Leydig cells outside the testicular parenchyma. Inflammatory changes associated with a hydrocele and a variety of granulomatous and nongranulomatous infectious disorders may mimic a neoplasm on gross evaluation, but should be readily distinguished from them microscopically. This is also the case with malakoplakia and sarcoidosis, which rarely form a paratesticular mass. Other lesions considered are changes associated with vasculitis, the recently described entities inflammatory pseudotumor and fibromuscular hyperplasia and the well-known processes sperm granuloma, spermatocele, vasitis nodosa, fibrous pseudotumor, meconium periorchitis, mesothelial hyperplasia, the testicular tumor of the adrenogenital syndrome, sclerosing lipogranuloma, and splenic-gonadal fusion. Features that aid in the microscopic distinction of these lesions from neoplasms are emphasized.