The only way to diagnose Lymphoma
is by biopsy of a swollen node. They can do blood
tests and scans, but these are often only used as a tool if the doctor suspects cancer.
From what I've read about Mono, there is a long list of symptoms that patients can present with, a sore throat being the most prevalent, but also fatigue, fever, headache, and swollen lymph nodes (just to name a few).