Appendiceal mucinous neoplasms are relatively rare. Following rupture of a mucinous neoplasms of the appendix, mucus can implant into the scrotum along the congenital or acquired inguinal space. We report a case of a testicular mucinous neoplasm with no preoperative abdominal lesions. Scrotal ultrasound showed an irregular mass in the right testis and inguinal area, with uneven echogenicity (stripe hyperechoic layered distribution) and no obvious blood flow signals. Ultrasound diagnosis was suspected as mucinous neoplasm. Postoperative pathology was confirmed to be low-grade mucinous neoplasm of the testis. Subsequently, the surgeon performed laparoscopic exploration and found that the appendix tumor had ruptured and the peritoneal cavity was implanted, and an appendectomy was performed. Postoperative pathology confirmed a low-grade appendix mucinous neoplasm. The evaluation and discovery of a scrotal mucinous neoplasm requires exploration of the appendix with ultrasound imaging. Even if the inner diameter of the appendix is normal but the presence of ascites, appendiceal mucinous neoplasms need to be considered.