Testicular tumor is relatively uncommon, accounting for only 1%–2% of all male malignancies. However, it is the leading malignancy in males aged 15–34 years and is almost exclusively malignant in nature.
Etiology
The exact cause of testicular tumors is unknown, but cryptorchidism is strongly associated. Individuals with cryptorchidism have a 3–14 times higher risk of developing testicular tumors compared to the general population, even if early orchidopexy is performed. Other contributing factors include race, genetics, chemical carcinogens, infections, and endocrine factors.
Pathology
Testicular tumors are among the most complex tumors of the genitourinary and male reproductive systems in terms of composition, histological diversity, and the close relationship between tumor types and treatment options. They are classified into primary and secondary tumors. Primary testicular tumors are further divided into germ cell tumors and non-germ cell tumors. Germ cell tumors constitute 90%–95% of cases and are subdivided into seminomas and non-seminomatous germ cell tumors (NSGCTs). The latter category includes embryonal carcinoma, teratoma, choriocarcinoma, and yolk sac tumor, with tumors often consisting of mixed components. Non-germ cell tumors, accounting for only 5%–10% of cases, include Leydig cell tumors and Sertoli cell tumors.
Testicular tumors frequently metastasize to lymph nodes, initially spreading to the para-aortic and paracaval lymph nodes at the renal hilum level. Hematogenous spread may occur, causing metastases in the lungs, bones, or liver. Secondary testicular tumors mainly arise from malignancies such as lymphoma or leukemia.
Clinical Manifestations
Testicular tumors are most common in males aged 25–45 years. However, yolk sac tumors are more frequently observed in infants and young children, while testicular lymphoma typically occurs in men over the age of 50.
The typical presentation is unilateral testicular enlargement. Early in the disease, symptoms are mild or absent. As the tumor grows, the affected testis becomes firm and heavy, often accompanied by a sensation of dull ache or mild discomfort. In rare cases, the tumor presents abruptly as a painful mass, with local redness, swelling, and fever, which may be attributed to tumor hemorrhage, infarction, or necrosis, often mistaken for acute epididymitis or orchitis.
In cryptorchidism, a growing mass in the abdomen or inguinal region may indicate malignant transformation. Patients with testicular tumors that secrete human chorionic gonadotropin (HCG) may develop gynecomastia. About 10% of patients present with symptoms related to metastatic disease, such as back pain, cough, hemoptysis, lower extremity edema, or bone pain.
Diagnosis
Physical examination typically reveals an enlarged or palpable mass in the affected testicle, with a firm texture and indistinct boundaries, and the diseased testicle often feels heavier than the contralateral testicle. Transillumination tests are usually negative. Examination should involve the entire scrotal contents as well as superficial lymph nodes and the abdomen to assess for lymph node involvement.
Serum levels of alpha-fetoprotein (AFP), beta subunit of human chorionic gonadotropin (β-HCG), and lactate dehydrogenase (LDH) serve as key tumor markers. These markers assist in determining the histological type of tumor, clinical staging, recurrence after surgery, and prognosis. AFP is elevated in nearly all yolk sac tumors, 70% of embryonal carcinomas, and 50% of teratomas. However, it is typically normal in patients with choriocarcinoma or pure seminoma. Elevation of AFP in seminoma cases suggests the presence of non-seminomatous components.
HCG levels are elevated in 40%–60% of NSGCTs, 100% of choriocarcinomas, 40%–60% of embryonal carcinomas, and 10%–30% of seminomas due to the presence of syncytiotrophoblastic cells. Imaging studies such as ultrasonography, CT, and MRI are useful for diagnosing testicular tumors and assessing retroperitoneal lymph node involvement. Chest CT may help identify pulmonary and mediastinal metastases. Testicular tumors must be differentiated from conditions such as testicular torsion, epididymitis, hydrocele, indirect inguinal hernia, scrotal hematoma, and spermatic cord cysts.
Treatment
Radical orchiectomy should be performed as early as possible, followed by treatment plans based on tumor type and clinical staging. Seminomas with suspected retroperitoneal lymph node involvement may be treated with radiation therapy, often combined with cisplatin-based chemotherapy. For NSGCTs, treatment options may include close surveillance, retroperitoneal lymph node dissection (RPLND), or chemotherapy depending on the specific clinical context.