Temperature rise is an essential part of the inflammatory response against bacteria, viruses, and other pathogens. However, it is not limited to infections, and there are other infrequent causes of fever, including lymphoma. As such, if you only have fever and enlarged lymph nodes, your doctor would likely need to investigate other common causes (inflammatory or infectious) before starting to think about lymphoma.
What happens in lymphoma patients is that, since there is a severe compromise in the normal function of the immune system, lymphocytes start releasing various substances to your bloodstream at an abnormal rate. These substances are perceived by your brain as an alert sign that there’s an infection going on, and it would raise the temperature threshold in your body. As a response, your body starts to increase temperature lightly.
As a result, lymphoma patients have a low-grade fever, usually over 38 degrees Celsius. This symptom is frequent in lymphoma as well as many other diseases, which is why other signs and symptoms will be necessary to complete the suspicion.