We present a rare case of primary lymphoblastic B-cell lymphoma of the testis focusing on ultrasonographic and pathological features and clinical implications. Pathological examination revealed primary testicular lymphoblastic B-cell lymphoma which was treated with adjuvant chemotherapy, including rachicentesis with administration of chemotherapy and with radiotherapy of contralateral testis. Primary testicular lymphoblastic B cell lymphoma is an aggressive disease and it is necessary a multimodal therapy (surgery, chemotherapy and radiotherapy) to prevent metastasis.