Rare Leukemic Phase of Follicular Lymphoma With a High-Risk Follicular Lymphoma International Prognostic Index (FLIPI) Score Treated With Bendamustine-Rituximab

Follicular lymphoma is a slow-growing B-cell non-Hodgkin lymphoma, accounting for approximately 20 to 30% of global cases. The leukemic phase is a rare presentation. It is often associated with high-risk characteristics, high tumor burden, slow progression, diagnostic challenges, and unfavorable prognosis. Risk stratification using the Follicular Lymphoma International Prognostic Index (FLIPI) is crucial, since individuals classified as high-risk (FLIPI ≥3) have aggressive disease with inferior progression-free and overall survival outcomes. We report a case of a 51-year-old woman with extensive lymphadenopathy and leukocytosis, subsequently diagnosed with the leukemic phase of follicular lymphoma, with a FLIPI score of 3. She was treated with bendamustine and rituximab (BR regimen), along with supportive prophylaxis and growth factor support. The patient tolerated six cycles of the BR regimen with clinical enhancement and hematological stability. This case report emphasizes the pivotal role of integrating timely diagnostic evaluation, accurate risk stratification, and early incorporation of risk-adapted contemporary chemoimmunotherapy approaches in the management of the leukemic phase of follicular lymphoma, collectively leading to favorable patient outcomes.