The most common is lymph node swelling, which is known as "adenopathy". You may not necessarily feel other symptoms and that is why it may not be noticed easily.
Sometimes, aggressive and very aggressive lymphomas do cause symptoms, such as weight loss, lack of appetite, temperature, profuse sweats or fatigue.
Lymphadenopaties usually appear in the neck, the armpits or the groins. Sometimes, the size of the liver and the spleen may be enlarged. Other times, the lymphoma affects organs such as the stomach, bones, lungs, brain or testicle.
Whenever a swollen lymph node appears, i.e. a person feels "a lump", wherever it is located, it is important to see the doctor so that he/she can assess and determine if a test is needed, though the most common cause for an adenopathy is an infection, trivial in most cases.