Good morning I'd really appreciate help and support with the following;

My wife (aged 55) had her gall bladder removed on 9th January. This was a result of some unpleasant pain in her abdomen due to gall stones. Other than this issue my wife is in very good health and all went well with the operation and recovery.

Three weeks went by and she received a letter to attend the Haematology  Dept at a neighbouring hospital. The letter offered no real explanation and we checked with our GP who had not received any related correspondence. 
 

Unfortunately I couldn't attend the appointment where my wife was told she has suspected "Lymph node cancer."  Blood tests and a CT scan were carried out and she was told to wait for a phone call in the next 7 days. There was little in the way of explanations and my wife was so stunned she didn't ask the questions. 
 

This has hit us hard. She has absolutely no symptoms, lumps, sweats, itching etc. we can't understand what has been picked up from the removal of the gallbladder to where we are ?

Can anyone suggest what's gone on, likely to happen and could she have this cancer without any symptoms? 
 

Any help greatly appreciated.