Extranodal Follicular Lymphoma - a Retrospective Review and Comparison with Localized Nodal Follicular Lymphoma.

Follicular lymphoma arising in an extranodal site is uncommon and its natural history and treatment is poorly characterized in the literature. We retrospectively reviewed a large cohort of patients with stage I and II follicular lymphoma and analyzed the outcomes of patients with extranodal (EN-FL) presentations to identify sites of involvement and treatment outcome, and compared these to patients with nodal follicular lymphoma. From 1967 to 1999, 668 cases of limited stage follicular lymphoma (stage I and II) were treated at the Princess Margaret Hospital. Of these, 157 cases (23.5%) presented in extra-nodal sites. The most common site of presentation was in the head and neck area (42%) followed by gastro-intestinal tract (14.6%) then skin (10.8%). The majority of patients had stage I disease (61.8%). Pathological type was follicular grade I: 22.9%, grade II: 33.1%, and grade III: 43.9%. Treatment consisted of involved field radiation therapy in 72%, combined modality therapy in 22.3% and chemotherapy alone in 3.8%. The treatment changed over time with increased use of combined modality treatment (CMT) [1967–77: 10.5%, vs. 1989–99: 33%] mainly due to the adoption of CMT for follicular grade III lymphoma. Overall complete response rate (CR) to primary treatment was 93%; the CR rate for radiation alone was 97.3%. The cumulative incidence of relapse (RR) was 44% at 10 years. The RR at 10 years was higher for patients age >60 (62% vs. 49%; p =0.059) but did not vary according to stage, tumour bulk, gender or histologic grade. For extranodal lymphoma, the 10-year overall survival (OS) rate was 56% and the 10-year disease free survival (DFS) was 42% and was similar for major sites of presentation.

Comparison of Stage I–II Nodal and Extra-nodal Follicular Lymphoma

In conclusion, a significant number of patients with localized FL present with extra-nodal disease, involving diverse sites. Patients with EN-FL were more likely to have follicular grade III histology. OS, DFS and RR were similar to nodal follicular lymphoma. These results suggest that the clinical management of stage I and II extra-nodal follicular lymphoma should be the same as for nodal, and that a significant proportion of patients have prolonged DFS with radiation-based therapy.