B symptoms are non-specific systemic symptoms that can be associated with the presence of an underlying lymphoma, which is a cancer of the body’s immune system. Three symptoms — unintentional weight loss, fever, and night sweats — are considered to be in this category. These symptoms are traditionally associated with Hodgkin’s disease and non-Hodgkin’s lymphoma, and their presence contributes towards understanding the severity of the underlying disease. Other diseases can cause symptoms similar to the B symptoms, so patients with these symptoms should consult with a health care professional.
Most commonly, experts classify three different symptoms as B symptoms. One is having a significant unintentional loss of weight, typically greater than 10% of body weight, within the past six months. Weight loss attained through intentional diet and exercise is not considered to be unintentional weight loss. Another symptom is night sweats that are severe enough that they soak through the affected patient’s clothes and sheets. The final symptom is recurrent fevers, reaching recorded temperatures of greater than 100.4° Fahrenheit (38° Celsius), for at least three days.
The B symptoms are most closely associated with Hodgkin’s disease, a type of lymphoma, as well as non-Hodgkin’s lymphoma. Up to a third of patients with Hodgkin’s disease have these symptoms. The prevalence of the symptoms in non-Hodgkin’s lymphoma varies by the specific subtype of lymphoma that a particular patient has.
In some lymphomas, the presence or absence of B symptoms plays an important role in determining how far the cancer has advanced, and deciding which treatment modalities are most likely to be successful. They play a critical role in cancer staging, which is a systematic approach towards uniformly classifying the severity of a cancer. For Hodgkin’s disease, the Ann Arbor staging system requires doctors or other health care providers to determine whether or not the symptoms were present in a given patient. Ann Arbor's system includes unintentional weight loss, recurrent fevers, and night sweats as examples of these symptoms. Patients who have Hodgkin’s disease with B symptoms might have more extensive disease and require more aggressive treatment.
Patients who have B symptoms do not necessarily have lymphoma. People with any of these symptoms should visit a doctor to help determine the cause. Other conditions ranging from infectious diseases such as tuberculosis, to autoimmune conditions such as adult Stills disease could cause similar symptoms. Diagnosis of lymphoma is never made solely on the presence of B symptoms, and typically requires doing a biopsy of affected body tissue.