Secondary tumors of the testis are rare. Three categories are considered: lymphoma, leukemia, and metastatic tumors.

1. Lymphoma

Epidemiology & Pathology
Lymphoma is the most common testicular tumor in a patient over the age of 50 and is the most common secondary neoplasm of the testis, accounting for 5% of all testicular tumors. It may be seen in 3 clinical settings: (1) late manifestation of widespread lymphoma; (2) initial presentation of clinically occult disease and (3) primary extranodal disease.

Gross examination reveals a bulging, gray or pink lesion with ill-defined margins. Hemorrhage and necrosis are common. Microscopically, diffuse histiocytic lymphoma is the most common type.

Clinical Findings
Painless enlargement of the testis is common. Generalized constitutional symptoms occur in one-fourth of patients. Bilateral testis involvement occurs in 50% of patients, usually asynchronously.

Treatment & Prognosis
Radical orchiectomy is indicated to make the diagnosis. Further staging and treatment should be handled in conjunction with the medical oncologist. Prognosis is related to the stage of disease. Some reports support adjuvant chemotherapy for primary testicular lymphoma, with improved survival rates of up to 93% after 44 months of follow-up.

2. Leukemic Infiltration Of the Testis

The testis is a common site of relapse for children with acute lymphocytic leukemia. Bilateral involvement may be present in one-half of cases. Testis biopsy rather than orchiectomy is the diagnostic procedure of choice. Bilateral testicular irradiation with 20 Gy and reinstitution of adjuvant chemotherapy constitute the treatment of choice. Prognosis remains guarded.

3. Metastatic Tumors

Metastasis to the testis is rare. These lesions are typically incidental findings at autopsy. The most common primary site is the prostate, followed by the lung, gastrointestinal tract, melanoma, and kidney. The typical pathologic finding is neoplastic cells in the interstitium with relative sparing of the seminiferous tubules.