Follicular lymphoma (FL, previously called follicle center lymphoma) is the second most common type of non-Hodgkin lymphoma (NHL). It is the most common of the indolent NHLs defined as those lymphomas in which survival of the untreated patient is measured in years. (See "Classification of the hematopoietic neoplasms".)
The vast majority of patients treated for FL will have an initial response to therapy with 40 to 80 percent demonstrating a complete response, depending upon the initial regimen used. Unfortunately, conventional therapy for FL is not curative and virtually all of these patients will ultimately develop progressive disease. In addition, less than 10 percent of patients treated with initial chemoimmunotherapy will not respond to treatment (ie, refractory disease).
The treatment of relapsed or refractory FL is discussed here. The treatment of previously untreated FL is presented separately as are the epidemiology, clinical presentation, pathologic features, diagnosis, and pathobiology of follicular lymphoma. (See "Initial treatment of advanced stage (III/IV) follicular lymphoma" and "Initial treatment of limited stage (I/II) follicular lymphoma" and "Clinical manifestations, pathologic features, diagnosis, and prognosis of follicular lymphoma" and "Pathobiology of follicular lymphoma", section on 'Introduction' and "Pathobiology of follicular lymphoma".)
EVALUATION OF SUSPECTED RELAPSE OR RESISTANCE
Definitions — After initial therapy, patients are followed at routine intervals to monitor for treatment-related complications and relapse. At these visits, patients are evaluated with a history, physical examination, and blood work. Imaging studies are reserved for the evaluation of suspected relapse. (See "Initial treatment of limited stage (I/II) follicular lymphoma", section on 'Long-term management' and "Initial treatment of advanced stage (III/IV) follicular lymphoma", section on 'Long-term management'.)
Progressive disease (PD) or relapse after complete remission (CR) most commonly presents as asymptomatic enlargement of the lymph nodes, liver, or spleen. By definition, PD or relapse after CR reflects the appearance of any new lesion, a 50 percent increase in the longest diameter of a previously identified lesion, or new/recurrent involvement of the bone marrow (table 1). Not all patients with PD or relapsed disease require imaging studies or biopsy at the time of progression: