Retroperitoneal lymphatic malformation causing scrotal swelling– a useful diagnostic work-up with two-phase MRI to differentiate from scrotal lymphatic malformation or abdomino-scrotal hydrocele

Abstract Background Lymphatic malformation (LM) is an abnormal collection of lymphatic fluid within cysts or channels. LM can occur in any part of the body, but LM leading to scrotal swelling is very rare, and this unusual location often leads to diagnostic errors because the most common cause of a scrotal cystic lesion is a hydrocele. Summary In the case presented here, a previously healthy 3-year-old boy recently developed a left scrotal swelling clinically mimicking a communicating hydrocele. However, a diagnostic laparoscopy showed a cystic lesion at the left internal inguinal ring with a closed internal inguinal ring, which is not an expected finding of communicating hydrocele. Differential diagnoses at surgery were scrotal LM, retroperitoneal LM, or abdomino-scrotal hydrocele (ASH). Two phase MRI performed both at the time of scrotal swelling and scrotal non-swelling showed a retroperitoneal LM bulging into the scrotum via the inguinal canal. Therefore, the retroperitoneal LM was completely resected using the inguinal approach. Conclusion LM causing scrotal cystic lesion is rare, and it requires a high index of suspicion to make the correct diagnosis. Laparoscopy was needed to rule out the communicating hydrocele, and two-phase MRI was very useful to differentiate retroperitoneal LM causing scrotal swelling from scrotal LM or ASH. Both examinations helped with diagnosis and treatment planning.