My 19 Year Old Son Went To The Emergency Hospital

My 19 year old son went to the emergency hospital for what we thought was a ingunial hernia off of his pelvic bone. They completed blood work, urinalysis, and a ct scan. The doctors diagnosed him with lymphadenopathy and referred him to oncologist. After a follow up for a previous ear infection the doctors told him his liver and spleen are also enlarged. They are also very concerned about the swollen lymph gland. He only takes diclofenac for a previous knee reconstruction one year ago. what can this be? Please help us understand this illness.