The value of contrast-enhanced ultrasonography in the diagnosis of primary testicular non-neoplastic and neoplastic lesions in adults.

Background: Different pathological types of testicular tumors are treated differently. Malignant germ cell tumors require radical orchiectomy, while benign tumors may only need mass enucleation. Contrast-enhanced ultrasonography (CEUS) is more sensitive than conventional ultrasonography in displaying tumor microvessels, which helps distinguish between benign and malignant tumors.

Methods: This was a retrospective analysis of 35 patients with pathological-confirmed primary testicular non-neoplastic and neoplastic lesions in our hospital from February 2017 to February 2022. Conventional ultrasonography and CEUS imaging findings of included lesions were retrospectively analyzed and their diagnostic values were compared with the pathological results.

Results: There were 13 cases of benign testicular lesions (including 1 case of spontaneous hematoma, 2 cases of segmental infarctions, 5 cases of epidermoid cysts, 2 cases of Sertoli cell tumors, and 3 cases of Leydig cell tumors) and 23 cases of malignant testicular lesions (including 10 cases of seminomas, 1 case of embryonal carcinoma, 2 cases of mixed germ cell tumors, 2 cases of spermatocytic tumors, and 8 cases of lymphomas). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy rates of conventional ultrasound in diagnosing benign testicular tumors by "onion skin-like" echo (epidermoid cysts) and peripheral annular blood flow were 30.8%, 100.0%, 100.0%, 71.9% and 75.0%, respectively. All testicular non-neoplastic lesions and epidermoid cysts showed no enhancement by CEUS. All Sertoli-Leydig cell tumors (SLCTs)' CEUS imaging showed uniform high enhancement (no necrosis area), fast forward, and slow backward. 80.0% (12/15) malignant germ cell tumors showed heterogeneous enhancement and fast forward and fast backward in CEUS. All lymphomas showed fast forward and fast backward, and 87.5% (7/8) of them showed uniform high levels of enhancement in CEUS. According to CEUS without enhancement (non-neoplastic lesions and epidermoid cysts) and uniform high enhancement with fast forward and slow backward (SLCT), the sensitivity, specificity, positive predictive value, negative predictive value and accuracy rates for diagnosing benign testicular tumors were all 100.0%. Compared with conventional ultrasound, the difference was statistically significant (p = 0.004).

Conclusions: CEUS could accurately distinguish between benign and malignant testicular tumors, as well as differentiate specific pathological types (testicular focal infarction, epidermoid cysts, spermatocytic tumors, SLTC and lymphoma). Accurate preoperative diagnosis is critical for guiding the selection of appropriate treatment plans for different pathological types of testicular tumors.