Benign fibromatous tumors of the testis and paratesticular region: a report of 9 cases with a proposed classification of fibromatous tumors and tumor-like lesions.

Benign intrascrotal fibrous proliferations are uncommon, with most arising from the paratesticular region and falling into the category of so-called fibrous pseudotumor. We describe two neoplastic forms of benign fibrous tumor of the testis and its adnexa: fibroma of gonadal stromal origin and fibroma of the testicular tunics. Three patients with gonadal stromal fibroma were 28, 33, and 35 years of age and presented with painless masses. The tumors were circumscribed, intratesticular, yellow-white or white lesions 0.9 to 4.0 cm in diameter and had microscopic features identical to those of the ovarian fibroma. Immunohistochemically, the tumor cells were strongly positive for vimentin (3/3 cases), focally positive for actin and desmin (2/3 cases) and negative for S-100, keratin, and CD34 (3/3 cases). Six fibromas of the testicular tunics arose in patients 22, 34, 60, 68, 70, and 74 years old and were also asymptomatic masses. Four of them were circumscribed, whorled, white masses arising from the tunica albuginea with variable areas of myxoid change; one was pedunculated and grew exclusively into the cavity of the tunica vaginalis, whereas the other three at least partially extended into the testis as well. The other two tumors were unattached to the tunica albuginea and presented as circumscribed, white-tan paratesticular masses, partially covered by tunica vaginalis. Microscopically, the tumors were slightly to moderately cellular, with bland spindle or stellate cells lying in a myxoid or collagenous stroma with prominent vessels. The two paratesticular tumors had features typical of solitary fibrous tumor. Immunohistochemically, the fibromas of the testicular tunics were negative for S-100, keratin, and desmin. Focal, weak reactivity for actin was present in one case. CD34 was positive in three cases; in the two tumors resembling solitary fibrous tumors it was strong, and in the other it was focal and was limited to the region just below the tunica vaginalis. Eight tumors were treated by radical orchiectomy and one by excision of the mass alone. The outcome was benign in the seven cases in which followup information is available.