From the Guidelines

Lymphoma metastasizing to the testicle is a rare and serious condition that requires prompt medical attention.

Metastasis Route: Malignant testicular germ-cell tumors, including lymphoma, metastasize by either the hematogenous or lymphatic route, with nodal metastases typically following the testicular lymphatic drainage pathway alongside the testicular veins to regional lymph node groups 1.
Prognosis and Treatment: The prognosis and treatment of testicular cancer, including lymphoma metastasis, depend on the stage and type of cancer, with overall long-term survival rates of 97% for testicular cancer patients 1.
Staging and Surveillance: Staging of testicular cancer is based on the tumor, nodes, and metastases (TNM) staging system, and imaging is used to assess for expected locations of lymph node involvement and metastatic disease, with surveillance being a crucial part of management, especially for stage I pure seminoma testicular cancers 1.
Lymphatic Drainage: The lymphatic drainage of the testicles is an important factor in the spread of cancer, with tumors from the left testis metastasizing to the left para-aortic nodal group and tumors from the right testis metastasizing to the paracaval, precaval, and inter-aortocaval groups 1.
Clinical Management: Clinical management of lymphoma metastasis to the testicle involves a multidisciplinary approach, including surgery, chemotherapy, and radiotherapy, with the goal of achieving complete remission and preventing further metastasis 1.

From the Research

Lymphoma metastasizing to the testicle is a rare and aggressive condition, with primary testicular lymphoma (PTL) being an intermediate to high-grade tumor [ 2 ].
The most common type of PTL is diffuse large B-cell lymphoma (DLBCL), which has a less aggressive course and better prognosis compared to nodal DLBCL [ 2 ].
Metastasis is uncommon in testicular DLBCL, but when it occurs, common sites include the contralateral testes, Waldeyer's ring, skin, lung, central nervous system (CNS), and prostate [ 2 ].
The prognosis of testicular lymphoma is generally poor, with relapses often seen despite good initial responses to chemotherapy [ 3 ].
Testicular lymphoma often disseminates to other extranodal organs, such as the CNS, lung, pleura, Waldeyer's ring, and soft tissue [ 3 ].

The most common clinical presentation of testicular lymphoma is a unilateral painless scrotal swelling, sometimes with sharp scrotal pain or hydrocele [ 3 ].
Systemic B symptoms are present in 25-41% of patients with advanced-stage disease [ 3 ].
Bilateral testicular involvement is detected in 35% of patients [ 3 ].
Imaging studies, such as ultrasound and computed tomography (CT) scans, can help diagnose testicular lymphoma [ 4 ].

The recommended first-line treatment for patients with limited disease is orchiectomy followed by rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) combination chemotherapy, with CNS prophylaxis and prophylactic irradiation of the contralateral testis [ 3 ].
In more advanced or relapsed disease, management should follow the worldwide recommendations for nodal DLBCL [ 3 ].
Treatment has traditionally been with orchiectomy and combination chemotherapy, but only a minority of patients enjoy a prolonged disease-free survival [ 5 ].