A paratesticular mass may derive from a number of structures that surround the testis within the scrotum; most commonly, they derive from the spermatic cord.
Pathology
The masses can be categorized as benign (70%) or malignant (30%).
Etiology
Benign
- spermatic cord lipoma (most common paratesticular mass) 3
- adenomatoid tumor (most common epididymal mass) 2,3
- epididymal leiomyoma
- epidermoid inclusion cyst
- epididymal papillary cystadenoma (associated with von Hippel Lindau disease)
- rare entities
- leiomyoma
- spermatic cord fibroma
- scrotal hemangioma (very rare)
- mimics of tumors include polyorchidism and splenogonadal fusion 3
- scrotal hemangioma
Malignant
- spermatic cord sarcomas 3
- adults
- rhabdomyosarcoma (most common; ~40% of paratesticular tumors 3)
- malignant fibrous histiocytoma (rare)
- spermatic cord leiomyosarcoma (rare)
- spermatic cord liposarcoma (rare)
- malignant schwannoma
- myxochondrosarcoma
- children
- adults
- metastases: <10% of epididymal masses are metastases 3