Transformed Follicular Lymphoma: The Role of the Pathologist in Aiding Therapeutic Decision Making

Follicular lymphoma (FL) is the second most common subtype of non-Hodgkin lymphoma. Follicular lymphoma is generally an indolent disorder, and despite being incurable with standard chemotherapy, recent advances in treatment strategies have improved clinical outcomes and survival. Over time, FL could acquire additional genetic mutations and transform into diffuse large B-cell lymphoma, a more aggressive B-cell neoplasm, which markedly reduces survival. Treatment of transformed FL is based on combination chemotherapy and immunotherapy. Rituximab has changed the treatment landscape in FL. However, novel approaches to treatment of transformed FL are in development. Here, we present a case of FL with transformation to diffuse large B-cell lymphoma and review diagnostic modalities along with current and upcoming therapies, many of which require assessment of antigen expression patterns from the pathologist. In particular, we will highlight the role the pathologist plays in management decisions.